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Implant Dentures: Follow-up after Seven to Ten Years
R . L. B odine,* D .D.S. San Juan, Puerto R ico
IMPLANT D EN TURES:
F ig . I • (P a tie n t I ) A : Four year postinser tion clin ica l exam ination revealed excellent oral health. B: Four year postinsertion roent genogram revealed small region of bone re sorption under posterior abutm ent. C : Seven and a h alf ye a rs’ postinsertion, there was serious d eterio ratio n . D : Seven and a half y e a r postinsertion roentgenogram revealed m oderate bone resorption extending to disto b u ccal perip h ery. E: In section o f un healthy tissue from near im plant abutm ent, stra tified squamous epithelium is thickened and has inflam m atory infiltration
Follow-up after Seven to Ten Years
From 30 patients who had had implant dentures for from 7 to 10 years, five w ere selected at random and exam ined. A ll five
reported
com fort
and
efficiency
greater than they had obtained from pre vious conventional dentures. O n e pa tient’s implant denture was virtually p er fe c t ; three had minor deficiencies not affecting com fort, efficiency or early prognosis; one had serious deficiencies requiring removal. P roperly made im plant dentures usually remain clinically healthy for at least seven years. Current evidence suggests that not m ore than fou r penetrating abutm ents should be used.
T here are many ways to im prove the stability and retention o f the com plete denture. All are im portant since they in crease com fort and efficiency and, by the application o f these principles, most pa tients can be taught to accept and be rea sonably satisfied with their dentures. Nonetheless, all such m ethods, for ex ample, proper utilization o f available basal seat area, the extension o f the an terior lingual sulcus or elimination by surgery o f other anatomic com plications and the use o f repelling magnets in the teeth or magnets im planted in the m an dible under the denture, have one serious
limitation in com m on. T h e final result is always a denture resting entirely on the oral mucosa, one limited in efficiency and retention by the tolerance o f soft tissue. T h e implant denture is com pletely d if ferent.1 T h e oral mucosa is relieved of any pressure from the im plant superstruc ture, and masticating forces are transmit ted entirely to an implanted substructure enmeshed in tough fibers o f the m andibu lar periosteum.2 This makes the implant denture roughly com parable to an exten sive removable partial denture supported by cuspids and second molars. T h a t the im plant denture is m ore efficient and com fortable needs no elaboration. D en tures supported and retained by the oral m ucosa never can approach the com fort and efficiency o f the im plant denture sup ported by bone. A wider acceptance o f the implant denture principle and its m ore general use for those patients who cannot be treated adequately with mucosa-supported den tures depends on how well the semiburied implant is tolerated by the oral tissue over many years. T h e region around the fou r abutments protruding into the oral cavity and the bone under the im planted fram e work have always been matters for co n cern. T h e probable life expectancy o f the im plant denture has been controversial. W hen, at the 1955 Am erican D ental A s sociation meeting, I presented the his
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tories o f three patients with satisfactory im plant dentures w hich then had been in place 2 to 3 years,3 I was misquoted by the press as having said that im plant dentures w ould last only three years. W hen a panelist at the 1959 Am erican Dental Association Centennial M eeting stated that the oldest im plant denture he had observed had been installed fo r seven years,4 he was misquoted as having said that implant dentures can be expected to last only for 6 to 7 years. In order to clarify this situation, in July, 1962 I personally examined 4 o f 30 patients with im plant dentures whose progress I have been follow ing and ar ranged for another o f these patients to be examined by another prosthodontist. All patients had had their im plant den tures for 7 to 10 years. Photographs and roentgenograms were obtained. A m ajor portion o f this report is based on inform a tion learned from these examinations. PATIENT HISTORIES
Patient 1 • A 43 year old man received his m andibular im plant denture on D ec. 15, 1954, and his progress had been fo l low ed for seven years. T his was my tenth im plant m ade from a bone impression and the first m ade in w hich a fairly ade quate technic was used. A t that time, an adequate impression material had not been found. T h e impression was made
F ig . 2 • (P a tie n t 2 ) Im plant substructure made from Thiokol ru bb er im pression fit bone a c c u rately
in m odeling plastic lined with M ucoseal which gave a moderately g ood impression. In addition to the usual four abut ments, two penetrating rests were placed experimentally between the abutments on each side in an attempt to support the superstructure more adequately and trans fer mastication stress to the im planted substructure at six points.5 A t insertion, the im plant fit the bone reasonably well. T h ree screws, one anterior and tw o pos terior, were used fo r primary fixation. H ealing was excellent. Four months after insertion, the tissue over the im plant and around the abut m ent and rest penetrations was entirely healthy, and the abutments were being kept clean by excellent oral hygiene. T h e im plant superstructure fit accurately and was relieved from the tissue so that all stress was carried by the im plant sub structure. Annual follow -ups by correspondence from 1955 to 1959 revealed n o implant deficiencies, and the letters were filled with such statements as, in 1956, “ I can truthfully say that at no time has there been the slightest indication o f any irri tation o f my gums” and, in 1957, “ This was the best thing that ever happened to m e.” Photographs (Fig. 1, A ) and roentgen ograms (Fig. 1, B) accom panied the O c tober, 1958, follow -up fou r years after insertion. T h e bone under the im plant on the left side appeared norm al; however, on the right side, there was a small am ount o f bone resorption under the pos terior abutment. T his is seen under many abutments o f implant dentures that have been in place a num ber o f years and generally has been considered a normal reaction to mastication stress. I suspect it m ay be accom panied by a slow dow n growth o f epithelium into the region so that a tight-fitting epithelial pocket forms under the abutment. Alm ost five years after insertion, the patient wrote, “ Sir, I have never had one minute’s trouble since the first day I got the im plant; I will be eternally grate
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.VO LUM E 67, SEPTEMBER 1963 • 45/355
ful to you.” In January, 1961 he stated that his im plant was still excellent, but he seemed somewhat less enthusiastic than previously. T h e first admitted indication o f trouble was in M arch, 1962 when he said, “ T w o o f the screws have com e out, and now it bleeds around the right posts when I brush.” W hen I examined this patient on July 9, 1962, his seven and a half year old im plant was in p oor condition. T here was severe interceptive contact on the right posterior side. For the past year o r year and a half, he had been chew ing mostly on the left side. T here was a large region o f hyperplastic tissue opposite the right posterior abutment, where repeated swell ing had caused the tissue to press against the im plant superstructure. Surprisingly, he wore both dentures night and day and chew ed on the left side without discom fort. H e demonstrated this by vigorously biting dow n on applicator sticks w ithout pain. W hen the superstructure was rem oved from the im plant abutments, serious de ficiencies were revealed in the im plant (Fig. 1, C ) . T here was a considerable am ount o f calculus form ation around the necks o f all abutments and rests extend ing dow n into the tissue crevices. T h e mucosa around the abutment and rest penetrations was loose and could be blow n away from the metal. O n the left, buccal to the posterior abutment, there was a region o f granulation tissue but n o visible suppuration. Roentgenogram s o f the left side showed the im plant to be in nearly the same rela tion to the mandibular b on e as originally. T here appeared to be m oderate resorp tion o f bone under the posterior abutment extending to the distobuccal periphery (Fig. 1, D ) . T h ere were serious deficiencies on the right side. T h e narrow im plant super structure rested between the hyperplastic tissue and the posterior abutment. T h e im plant seemed to be exfoliating on the right side. T h e most serious defect was in the right lingual region where the
Fig . 3 • (P atie n t 2) A b o v e : Seven years' post insertion, im plant denture is p e rfe ct. Below: Roentgenogram revealed healthy bone without sig n ifica n t resorption
peripheral metal was exposed and lay outside the tissue from the anterior abut m ent back. Surprisingly, there was no discernible m ovem ent o f the implant on application o f m oderate pressure to the abutments. A roentgenogram o f the right side con firmed the clinical finding o f exfoliation. From the space between metal and bone, w hich may have been exaggerated by the angulation, it was difficult to see how even the buccal portion o f the im plant could be covered with tissue and the im plant firmly fixed. T h e superstructure was retained by clasps w hich still fit so securely to the im plant abutments that removal o f the su perstructure was difficult. This unneces sarily tight fixation o f the superstructure, with the patient’ s chewing primarily on the left side during recent years, m ay have been a contributing factor in the exfoliat ing tendency o f the right side o f the im-
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plant; m oreover, the patient tended to form heavy calculus. T h ick calculus was apparent on the anterior lingual surface and the undersurface o f the superstruc ture. Since this im plant was hopeless, it was removed the next day. It was easy to re m ove on the right side but difficult on the left. A surprising finding was that a section o f bone had grown over the lingual periphery in the region o f the mandibular torus on the left side. Such a deposition o f bone over the im plant frame in various regions has been observed in other implants rem oved after three or more years. Considerable mutilation of tissue in removing an im plant is unavoid able. Because the substructure is encapsu lated in fibrous tissue, the m ucoperiosteum must be split. It cannot be elevated cleanly from the bone. Another im portant observation was that apparently norm al m ucosa was vis ible in a 15 by 15 m m . area under the left posterior abutment. Since this was rela tively healthy, it seems to confirm the supposition that epithelium invades the small resorbed regions frequently observed to form under im plant abutments after a num ber o f years. T his downgrowth may be the cause of, or an accom panying ef fect of, the bone resorption. Close examination o f the im plant sub structure after removal revealed not only calculus deposits around the necks o f the implant abutments but also stains and d e posits on and under the substructure framework near the abutment and rest penetrations. T his indicated that there had been seepage o f oral fluids into these regions and revealed the extent o f the pocket form ation. T h e metal was bright elsewhere, which seemed to indicate ab sence o f epithelial dow ngrow th or, at least, o f seeping o f oral fluids beyond the regions adjacent to the abutment. It must be remembered that this imF ig . 4 * (P a tie n t 3) A : Im plant denture substructure inserted A u g . 6, 1953. B: Seven years' postinser tion, im plant denture is c lin ic a lly sound with some loss o f tissue at the rig h t an terio r abutm ent. C : N ine years' postinsertion, th ere are no sig n ifica n t changes from two years b efo re. D : N ine years' postinsertion, roentgenogram reveals normal underlying bone w ithout sig n ifica n t resorption
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plant was not typical since the gingival tissue around all abutments was loose. T h e seepage may not occu r in m ore typi cal implants where the tissue is tight around the necks o f the abutment pene trations. Sections o f apparently healthy and o f abnormal tissue rem oved from around the abutments and sections o f the bone d e posited over the im plant periphery were examined by a pathologist (Fig. 1, E ) . All three specimens were lined with stratified squamous epithelium w hich was thick ened in many places. In the apparently healthy specimens o f tissue around the abutments, there was inflammatory infil tration ; in the abnormal specimens o f tis sue, severe inflammation. T h e inflamma tion was primarily in the superficial dermis and involved the lower portion o f the epidermis; there was n o malignancy. T h e section o f bon e had no abnormalities. This im plant probably should not be considered a com plete failure. It might be called a seven year partial success since the patient had seven years o f implant denture com fort after his years o f strug gle with ordinary dentures. His implant denture had appeared satisfactory under professional examinations for at least six years. Patient 2 • A 41 year old wom an re ceived her mandibular implant denture on M ay 10, 1955, just a few months after the previous patient. W hen I examined her on July 9 and 10, 1962, seven and a half years later, it was perfect. T h e patient was first seen about a year before the im plant was made, when she was wearing her lower denture which she had stuffed with cleansing tissue to re store lost vertical dimension. Since she changed the tissue several times daily, keeping it scrupulously clean, her mouth was healthy except for the com plete re sorption o f the residual ridge. T o give her temporary but immediate relief, her denture was supported with 7 mm . o f w ax on each side; then it was built up and corrected by several succes
sive self-curing resin relinings. For co m parison, duplicate dentures were made, one with C oe M asticator and one with Hardy Bladed posterior teeth. She wore the dentures alternately, keeping a diary o f her reactions. It soon becam e obvious that masticating com fort and efficiency were minimal. Six months later, a call was received from her physician. She had becom e de spondent, had been hospitalized and had lost 35 lb. In consultation with the psy chiatrist, it was concluded that her de spondency was related to her denture problems and that an im plant denture might be the key to her recovery. I was reluctant to undertake an implant den ture under these circumstances, but they wanted her to have encouragem ent and hope. A fter considerable consultation, she was told that, if she recovered her health and could be cleared fo r surgery, an implant denture w ould be attempted. She im proved and, on April 10, 1955, her implant denture was inserted; this was the last in a series o f 13 mandibular implant dentures m ade at Fort G ordon, Ga. between 1951 and 1955. T h e implant, our first made from a T hiokol rubber impression, fit the bone accurately (Fig. 2 ). T hiokol rubber was the first satisfac tory bone impression material, and today it is preferred for im plant bone impres sions.6 A loose-fitting immediate temporary superstructure was placed as a surgical splint and to maintain occlusion, along with an elastic head bandage to keep the splint in occlusion, limit edem a and sup port peripheral tissue. A fter two weeks, the tissue had healed with no secondary metal exposure. Since I was being transferred, her superstruc ture was rushed to com pletion, and I did not see her again for over seven years. In annual reports by mail during the interim, she insisted that her im plant was perfect and denied ever having any inflammation or irritation in her m outh. W hen she was seen next, her general health and spirits had remained excellent.
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F ig . 5 • [P a tie n t 4 ) L e ft: Three years a fte r insertion of patient's first im plant denture, the im plant is sa tisfa cto ry : a few months later, it had to be rem oved because of a break in the m etal substructure. R ig h t: Seven years a fte r insertion o f p atient's second im plant denture, conditions are fa irly satisfacto ry
She had been treated by a dentist only on ce during the seven years, at which time she was given a prophylaxis o f the im plant abutments. T h e occlusion had remained w ithout visible change, and there was n o discernible loss o f vertical dimension. W hen the implant superstructure, which she said had always been rather loose, was rem oved, the implant denture was perfect (Fig. 3, a b o v e ). T h e tissue was tight around the fou r abutments, and the gingival crevice appeared normal. T here was no secondary metal exposure or inflamed tissue. Roentgenograms re vealed healthy bone with the metal in close relationship to the bone without vis ible resorption or suggestion o f epithelial downgrowth (Fig. 3, b e lo w ). A fter the im plant superstructure had been left out overnight, a pressure indi cator showed some small areas o f slight pressure o f the superstructure on the un derlying m ucosa and other areas where there was about 1 mm. space between the denture and the tissue. A fter these small pressure areas were relieved, the super structure was relined with self-curing re lining material, after which it was again relieved, using pressure indicator, to be certain that there was n o pressure on the tissue and that all stress was transmitted to the im plant abutments. T h e clasps o f the superstructure fram e were tightened slightly, and the upper conventional den ture was relined.
It was impossible to find anything to criticize about this implant denture. Cer tainly, it had been accepted by the oral tissues, and there was n o condition from which to anticipate trouble in com ing years. This patient could expect a favor able prognosis for her im plant denture for many m ore years. Patient 3 • A 44 year old m an received our fifth bone impression m andibular im plant denture on Aug. 6, 1953 (Fig. 4, A .) Initial healing was excellent, al though the tissue was thin over the metal at the distolingual periphery near the mylohyoid ridge. W hen the patient returned fo r follow up examination two years later, his im plant was in good condition. T h e tissue still thinly covered the distolingual metal. This thinness o f tissue persisted without noticeable change fo r almost seven years. Seven years after insertion, the chroni cally thin tissue at the distolingual periph ery perforated. H e was treated by another dentist and, although there was slight re sorption o f tissue at the right anterior abutment, the implant was clinically healthy (Fig. 4, B ) . T h e section o f ex posed metal was cut from the lingual pe riphery, and the region healed without com plication. W hen I examined this patient on July 16, 1962, his im plant denture had been in place nine years, the longest o f those I examined in this group. T h e recession
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at the labial side o f the right anterior abutment was about the same as it had been tw o years before (Fig. 4, G.) T h e region at the distolingual periphery, where the metal had been cut o ff two years before, had healed and was as healthy as the rest o f his m outh. Roentgenogram s showed no com plica tion as a result o f this m odification and no evidence o f settling or bone resorp tion (Fig. 4, D ) . T h e im plant superstructure fit securely but not tightly. Other than moderate wear o f the acrylic resin teeth, the o c clusion had not changed, and there seemed n o loss o f vertical dimension. His maxillary denture and mandibular im plant superstructure were relined and the tissues relieved from superstructure pres sure. T his im plant denture was n ot in as g ood condition as the previous patient’s seven year old im plant; however, the de ficiencies were m inor, and there was
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nothing serious to affect the prognosis in the next few years. Patient 4 • A 23 year old man was par ticularly interesting because he had had two m andibular im plant dentures in the previous ten years. H e has hypopituitar ism, and com plete resorption o f his m ax illary and m andibular residual ridges had occurred when he was referred to us. His first im plant denture was our first bone impression implant, crudely made o f meshwork from a somewhat distorted m odeling plastic bone impression.2’ 5,7 It was inserted on April 26, 1952. In spite o f the technic, healing was u ncom pli cated, and it solved his difficult denture problem for three years (Fig. 5, le f t ). Three years after insertion, roentgeno grams revealed a com plete break in the implant substructure in front o f the right posterior abutment probably caused by a defect in the casting. T h e meshwork im plant was rem oved in M ay, 1955. O n
F ig . 6 • (P a tie n t 5) A : Meshwork im plant d enture using circum feren tial wire p rim ary fixation inserted Se p t. 25, 1952. B: Five years' postinsertion, im p lant is alm ost p e rfe ct. C : Ten years' postinsertion, there is slight loss of tissue a t an terio r abutm ents. D : Ten years' postinsertion, roentgenogram revealed m oderate bone resorption
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July 23, 1955, a technically im proved im plant denture was inserted. I examined this patient July 20, 1962, seven years after he had received his sec ond implant denture. Considering his endocrine imbalance and the p oor bone and soft tissues, this im plant denture may be considered suc cessful (Fig. 5, right) ; however, there were deficiencies. T here was a small ex posure o f metal on the right posterior side and a larger one on the left posterior side which had existed since insertion. Although the exposure on the left had grown slowly larger, there was no sup puration, and the tissue around it was healthy. T his patient had had little mandibular bone when he received his first implant ten years ago. Roentgenogram s revealed n o serious pathologic changes on the right side. O n the left, there was epi thelium under the exposed metal, and the space between the metal and the bone under the exposure was filled by m ucoperiosteum. Nonetheless, close examination showed good general oral health after seven years with his second implant denture. I f the three years o f his first implant are in cluded, he has had ten years o f implant denture com fort and efficiency. T h e p a tient was not aware o f deficiencies, and he considered his implant denture excel lent since he could eat well and was co m fortable. Although further deterioration m ay occur, it should be slow, and he should have at least a few m ore years o f satisfaction with his im plant denture. Patient 5 ' A 45 year old man, w ho re ceived our second bone impression im plant denture (Fig. 6, A ) on Sept. 25, 1952,2,3,8 was examined last summer by another prosthodontist. T his implant was the second o f only two m ade o f the cast screen mesh and had circumferential wir ing on each side for primary fixation. A t that time, we still were developing the implant technic. O n the fifth post operative day, the incision opened in the
anterior region and exposed the metal framework. Granulation tissue form ed rapidly through and over the meshwork. By two months, there was only a small spot o f metal exposed near the left an terior abutment. I next saw this patient on A pril 15, 1957, when his im plant denture was al most five years old. In spite o f the elem en tary technic and p oor initial healing, his m outh was healthy (Fig. 6, B ) . T h ere was only slight evidence that the metal had been exposed during the first few months. Roentgenograms showed norm al bone under the implant without change in posi tion or unfavorable reaction to the cir cumferential wiring. T his patient was examined on July 5, 1962, ten years after insertion (Fig. 6, C ) . T h e prosthodontist w h o examined him stated, “ T h e patient has been getting along fine with his im plant denture, but has lost some tissue around the abutments. I feel this is mainly due to his failure to maintain his oral hygiene. A fter thorough prophylaxis,' proper hom e care was reem phasized, and the dentures were equili brated. T his alleviated some o f the m u cous membrane irritation w hich was present.” Roentgenograms showed m oderate re sorption after ten years creating a small space under some o f the abutments (Fig. 6, D ) . T here was no reduction in co m fort and efficiency as shown by the pa tient’s statement in the follow -up o f April, 1962: “ I feel I have the masterpiece o f your profession; after ten years it is still perfect.” DISCUSSION
These five mandibular im plant dentures 7 to 10 years after insertion may or may not be typical o f implants in general; however, valid conclusions may be drawn. L ife E xpectancy o f Im plant D enture • W ith proper technic,6,9 successful im plant dentures can be m ade that will solve, fo r 7, 10 or m ore years, difficult
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com plete denture problems and give pa tients greater com fort and efficiency than can be expected from conventional m ucosa-supported dentures. Conventional dentures, even with proper borders, surgi cal extensions, magnetized teeth or im planted magnets cannot approach the im plant denture w hich uses the m andibu lar bone for support and stability. Some properly made implant dentures must be rem oved in as little as seven years; however, this does not indicate com plete failure, especially for patients in an im portant or difficult period of their lives. Some implant dentures are clinically perfect after 7 to 10 years and, fo r these, 15, 20 or more years o f implant life may be anticipated. M any implant dentures show some de terioration or deficiency after 7 to 10 years,10 which usually does not affect com fort or efficiency and is not im m edi ately unfavorable to implant prognosis. Some may fail after ten years, whereas others continue to serve satisfactorily, per haps with further slow deterioration, for m uch longer. T h e problem before those who con tinue to work with the implant denture is to im prove further basic technics,9,11’ 12 selection o f patients, follow -up care and oral hygiene so that the percentage o f implant dentures that fail in about seven years will be considerably decreased, and the percentage that are nearly perfect after 8, 10 and m ore years will be in creased substantially. R oentgenogram s • It is difficult to make clear roentgenograms because the opaque metal o f the im plant substructure and ac com panying elongation and distortion hide critical osseous regions. Perhaps the most useful technic is to use a film holder to place fast intraoral films vertically, parallel to and somewhat away from the implant abutments and to make longcone exposures at angles varying ( + ) 15, 0 and ( — ) 15 decrease from the hori zontal.
Im plant Oral Penetration • W ith tech nics and materials advocated today, the experienced implant dentist should have little difficulty in making the implant fit the bone accurately; however, after five or m ore years, a region o f bone resorption sometimes develops immediately under the im plant abutments. I suspect that, when this resorption is deeper than about 1 mm., there probably has been a dow ngrowth o f oral epithelium into the re gion. If the region is not too large and oral hygiene is good, the m ucosa may tightly grip the abutment, and the region may remain essentially healthy for 9, 10 or m ore years. I f oral debris seeps into the region with the deposition o f calculus on the buried metal, chronic irritation and inflamma tion will develop. Irrigations, antiseptics and better oral hygiene sometimes effect great improvement, but the condition tends to recur and may lead to gradual deterioration and eventual removal after seven or m ore years. N um ber o f Oral M ucosal Penetrations • Because o f the tendency to bone resorp tion, epithelial downgrowth and pocket form ation to develop around the oral penetrations o f some implants, the num ber o f penetrations becom es important. Use o f m ore than the minimum four abutments required for denture support and distribution o f stress probably is con traindicated. Secondary metal exposures which per sist after initial healing o r develop later can be considered factors which may lead to implant deterioration and must be eliminated or minimized by use o f proper technic. O ften metal exposures in im plants made before 1955 were caused by distortion in the m odeling plastic im pressions which developed when they were rem oved from m ylohyoid undercuts. Thus, the substructure did not fit the bone accurately and, on insertion, a space existed between the metal and the bone into which the overlying tissue contracted.
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Table • Twenty-two mandibular implant dentures, 5 to 10 years after insertion Implant no. 1
Date inserted
Years in place
April, 1952
3 10
2
Sept., 1952
3
April, 1953
4
April, 1953
5
June, 1953
6
Aug., 1953
7
Patient evaluation
Professional evaluation
Removed March, 1955
3 y e a r failure
Excellent
G ood
Excellent
Fair
91/4
Excellent
G ood
9
Excellent
Good
9
Good
Good
Dec., 1953
5
Removed Sept., 1958
5 year limited succ
8
Jan., 1954
8
Removed N ov., 1961
8 year limited succ
9
April, 1954
Vh
Removed O ct., 1961
7 xh
10
July, 1954
A/ a
Died O ct., 1958
4 /4
9/2
year limited succ year success
11
Dec., 1954
7/2
Excellent
Fair
12
May, 1955
m
Excellent
Excellent
13
May, 1955
VA
Excellent
Good
14
July, 1955
7
Excellent
Fair
15
Dec.. 1955
6/2
Excellent
Excellent
16
May, 1956
6/4
Excellent
Good
17
Sept., 1956
6
Excellent
Excellent
18
Sept., 1956
6
Excellent
Good
19
Sept., 1956
6
Good
Good
20
March, 1957
5/4
Excellent
Good
21
April, 1957
5/4
Excellent
Excellent
22
Aug., 1957
5
Excellent
Good
Attachm ent of Superstructure to Im plant Abutm ents • In the five im plant dentures studied 7 to 10 years after insertion, the superstructure attachment to the im plant abutments was rather tight in the worst and loose in the most successful. In none o f the other three was the attach ment particularly tight. T igh t fixation, the kind that makes rem oval by straight vertical stress difficult, may be an im por tant factor in predisposing to bone resorp tion, pocket form ation, shifting o f the implant substructure, metal exposure and eventual exfoliation, especially if accom panied by traumatic occlusion or abnor mal habits o f mastication. Therefore, I believe that the super structure should be attached to the im
plant abutments by precision fitting, with or without clasps, to produce positive resistance to occlusal and lateral stresses, yet afford only the m inim um resistance to vertical removal required for com fort and efficiency.8 T h e problem o f h ow to provide space for clasp action w ithout irritating the tissue around the im plant abutments has been solved. First, the acrylic resin is cured tight against the clasp. A no. 558 fissure bur is used to free the clasp from the acrylic resin, leaving a small space. After the clasp has been adjusted to give the minimal retention required, the space is filled with self-curing soft denture re lining resin. This type o f resin remains slightly elastic indefinitely and will allow
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for clasp action while making the under surface o f the superstructure smooth and nonirritating to the tissue. Evaluation • In the 1962 follow -up o f 30 implant denture patients, 22 had implants made from bone impression which had been in place from 5 to 10 years (see ta b le ). Four o f these had been removed. O n e was a technical failure (breaking o f the substructure); three (13 per cent) were true failures. M oreover, these three removed after 5, 7 j/i and 8 years might be considered partial successes. O ne pa tient died from unrelated causes five years after receiving his implant. In conclusion, five patients who could not be treated adequately with mucosaborne dentures have obtained satisfaction with implant dentures for a minimum of seven and a half years. T w o already have had ten years o f im plant denture effi ciency and com fort; one, nine years, and one, seven years. Four can anticipate an indefinite numbers o f years m ore service from their implants. SUMMARY
Five randomly selected patients with mandibular im plant dentures that had been in place for from 7 to 10 years were examined during July, 1962. T heir his tories were reviewed and roentgenograms and photographs obtained. A ll patients reported com fort and efficiency greater than they had obtained from previous conventional dentures. Critical clinical and roentgenographic examination revealed various conditions. O ne patient’ s im plant denture was virtu ally perfect; three had m inor deficiencies not affecting com fort, efficiency or early prognosis, and one had serious deficiencies requiring removal. A small region o f bone resorption often developed under the abutments after 3 to 4 years, which m ay represent a downgrowth o f oral epithelium. It had little
effect on im plant prognosis since the tis sue generally remained clinically healthy, closely gripping the neck o f the abutment in to the 7 to 10 year period. Occasionally, oral fluids seeped into the region with lim ited oral debris and calculus deposition, slight inflammation o f the tissue and pos sible slow extension o f the region o f re sorption and downgrowth. T his had little or no effect on denture com fort and effi ciency. Serious deterioration developed in only one patient. Properly made m andibular implant dentures usually remain clinically healthy for at least seven years. Current evidence suggests that not m ore than four penetrating abutments or rests should be used and that the attach m ent o f the superstructure to the implant abutments should afford only minimal re sistance to removal by vertical force.
Presented as part of a panel "Four approaches to achieving stability of complete dentures" before the Section on Compiete Prosthodontics, one hundred and third annual meeting, American Dental Association, Miami Beach, Fla., October 31, 1962. ^Associate professor of prosthodontics, School of Den tistry, University of Puerto Rico, San Juan, Puerto Rico. 1. Bodine, R. L., Jr. History and development of im plant dentures. Estratto da: Atti Secondo Simpòsio Internazionale degli Impianti Allopléstici a Scopo Pròtesi, Ñapóles, Italy. 253-262 Feb. 1958. 2. Bodine, R. L., Jr . The mandibular subperiosteal implant denture. Estrátto da: Atti Secondo Simpòsio Internazionàle degli Impianti Alloplàstici a Scopo Prò tesi, Ñapóles, Italy. 87-107 Feb. 1958. 3. Bodine, R. L., Jr . Implant dentures: prosthodontic —favorable. J . Pros. Den. 10:1132 Nov.-Dec. I960. 4. Archer, W . H. Implant dentures; surgical—unfavor able—qualified. J . Pros. Den. 10:1127 Nov.-Dec. I960. 5. Bodine, R. L., Jr. Prosthodontic essentials and an evaluation of the mandibular subperiosteal implant den ture. J.A .D .A . 51:654 Dec. 1955. 6. Bodine, R. L., Jr. The implant denture bone im pression; preparations and technique. J . Implant Den. 4:22 Nov. 1957. 7. Bodine, R. L., Jr., and Kotch, R. L. Experimental subperiosteal dental implants. U .S . Armed Forces M. J . 4:441 March 1953. 8. Bodine, R. J ., Jr. Implant dentures today. J . Im plant Den. 4:22 May 1958. 9. Bodine, R. L., J r . Implant dentures. Practical Den tal Monographs, Chicago, Year Book Medical Publica tions, Inc. May 1958, p. 1-40. 10. Bodine, R. L., Jr . Co-report: Implant dentures. Internat. D. J . 8:371 June 1958. 11. Bodine, R. J ., Jr., and Kotch, R. L. Mandibular subperiosteal implant denture technique. J . Pros. Den. 4:396 May 1954. 12. Bodine, R. L., Jr., and Kotch, R. L. Perfected mandibular subperiosteal implant denture technic. New York D. J . 20:193 May 1954.
IMPLANT D EN TURES:
F ig . I • (P a tie n t I ) A : Four year postinser tion clin ica l exam ination revealed excellent oral health. B: Four year postinsertion roent genogram revealed small region of bone re sorption under posterior abutm ent. C : Seven and a h alf ye a rs’ postinsertion, there was serious d eterio ratio n . D : Seven and a half y e a r postinsertion roentgenogram revealed m oderate bone resorption extending to disto b u ccal perip h ery. E: In section o f un healthy tissue from near im plant abutm ent, stra tified squamous epithelium is thickened and has inflam m atory infiltration
Follow-up after Seven to Ten Years
From 30 patients who had had implant dentures for from 7 to 10 years, five w ere selected at random and exam ined. A ll five
reported
com fort
and
efficiency
greater than they had obtained from pre vious conventional dentures. O n e pa tient’s implant denture was virtually p er fe c t ; three had minor deficiencies not affecting com fort, efficiency or early prognosis; one had serious deficiencies requiring removal. P roperly made im plant dentures usually remain clinically healthy for at least seven years. Current evidence suggests that not m ore than fou r penetrating abutm ents should be used.
T here are many ways to im prove the stability and retention o f the com plete denture. All are im portant since they in crease com fort and efficiency and, by the application o f these principles, most pa tients can be taught to accept and be rea sonably satisfied with their dentures. Nonetheless, all such m ethods, for ex ample, proper utilization o f available basal seat area, the extension o f the an terior lingual sulcus or elimination by surgery o f other anatomic com plications and the use o f repelling magnets in the teeth or magnets im planted in the m an dible under the denture, have one serious
limitation in com m on. T h e final result is always a denture resting entirely on the oral mucosa, one limited in efficiency and retention by the tolerance o f soft tissue. T h e implant denture is com pletely d if ferent.1 T h e oral mucosa is relieved of any pressure from the im plant superstruc ture, and masticating forces are transmit ted entirely to an implanted substructure enmeshed in tough fibers o f the m andibu lar periosteum.2 This makes the implant denture roughly com parable to an exten sive removable partial denture supported by cuspids and second molars. T h a t the im plant denture is m ore efficient and com fortable needs no elaboration. D en tures supported and retained by the oral m ucosa never can approach the com fort and efficiency o f the im plant denture sup ported by bone. A wider acceptance o f the implant denture principle and its m ore general use for those patients who cannot be treated adequately with mucosa-supported den tures depends on how well the semiburied implant is tolerated by the oral tissue over many years. T h e region around the fou r abutments protruding into the oral cavity and the bone under the im planted fram e work have always been matters for co n cern. T h e probable life expectancy o f the im plant denture has been controversial. W hen, at the 1955 Am erican D ental A s sociation meeting, I presented the his
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tories o f three patients with satisfactory im plant dentures w hich then had been in place 2 to 3 years,3 I was misquoted by the press as having said that im plant dentures w ould last only three years. W hen a panelist at the 1959 Am erican Dental Association Centennial M eeting stated that the oldest im plant denture he had observed had been installed fo r seven years,4 he was misquoted as having said that implant dentures can be expected to last only for 6 to 7 years. In order to clarify this situation, in July, 1962 I personally examined 4 o f 30 patients with im plant dentures whose progress I have been follow ing and ar ranged for another o f these patients to be examined by another prosthodontist. All patients had had their im plant den tures for 7 to 10 years. Photographs and roentgenograms were obtained. A m ajor portion o f this report is based on inform a tion learned from these examinations. PATIENT HISTORIES
Patient 1 • A 43 year old man received his m andibular im plant denture on D ec. 15, 1954, and his progress had been fo l low ed for seven years. T his was my tenth im plant m ade from a bone impression and the first m ade in w hich a fairly ade quate technic was used. A t that time, an adequate impression material had not been found. T h e impression was made
F ig . 2 • (P a tie n t 2 ) Im plant substructure made from Thiokol ru bb er im pression fit bone a c c u rately
in m odeling plastic lined with M ucoseal which gave a moderately g ood impression. In addition to the usual four abut ments, two penetrating rests were placed experimentally between the abutments on each side in an attempt to support the superstructure more adequately and trans fer mastication stress to the im planted substructure at six points.5 A t insertion, the im plant fit the bone reasonably well. T h ree screws, one anterior and tw o pos terior, were used fo r primary fixation. H ealing was excellent. Four months after insertion, the tissue over the im plant and around the abut m ent and rest penetrations was entirely healthy, and the abutments were being kept clean by excellent oral hygiene. T h e im plant superstructure fit accurately and was relieved from the tissue so that all stress was carried by the im plant sub structure. Annual follow -ups by correspondence from 1955 to 1959 revealed n o implant deficiencies, and the letters were filled with such statements as, in 1956, “ I can truthfully say that at no time has there been the slightest indication o f any irri tation o f my gums” and, in 1957, “ This was the best thing that ever happened to m e.” Photographs (Fig. 1, A ) and roentgen ograms (Fig. 1, B) accom panied the O c tober, 1958, follow -up fou r years after insertion. T h e bone under the im plant on the left side appeared norm al; however, on the right side, there was a small am ount o f bone resorption under the pos terior abutment. T his is seen under many abutments o f implant dentures that have been in place a num ber o f years and generally has been considered a normal reaction to mastication stress. I suspect it m ay be accom panied by a slow dow n growth o f epithelium into the region so that a tight-fitting epithelial pocket forms under the abutment. Alm ost five years after insertion, the patient wrote, “ Sir, I have never had one minute’s trouble since the first day I got the im plant; I will be eternally grate
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.VO LUM E 67, SEPTEMBER 1963 • 45/355
ful to you.” In January, 1961 he stated that his im plant was still excellent, but he seemed somewhat less enthusiastic than previously. T h e first admitted indication o f trouble was in M arch, 1962 when he said, “ T w o o f the screws have com e out, and now it bleeds around the right posts when I brush.” W hen I examined this patient on July 9, 1962, his seven and a half year old im plant was in p oor condition. T here was severe interceptive contact on the right posterior side. For the past year o r year and a half, he had been chew ing mostly on the left side. T here was a large region o f hyperplastic tissue opposite the right posterior abutment, where repeated swell ing had caused the tissue to press against the im plant superstructure. Surprisingly, he wore both dentures night and day and chew ed on the left side without discom fort. H e demonstrated this by vigorously biting dow n on applicator sticks w ithout pain. W hen the superstructure was rem oved from the im plant abutments, serious de ficiencies were revealed in the im plant (Fig. 1, C ) . T here was a considerable am ount o f calculus form ation around the necks o f all abutments and rests extend ing dow n into the tissue crevices. T h e mucosa around the abutment and rest penetrations was loose and could be blow n away from the metal. O n the left, buccal to the posterior abutment, there was a region o f granulation tissue but n o visible suppuration. Roentgenogram s o f the left side showed the im plant to be in nearly the same rela tion to the mandibular b on e as originally. T here appeared to be m oderate resorp tion o f bone under the posterior abutment extending to the distobuccal periphery (Fig. 1, D ) . T h ere were serious deficiencies on the right side. T h e narrow im plant super structure rested between the hyperplastic tissue and the posterior abutment. T h e im plant seemed to be exfoliating on the right side. T h e most serious defect was in the right lingual region where the
Fig . 3 • (P atie n t 2) A b o v e : Seven years' post insertion, im plant denture is p e rfe ct. Below: Roentgenogram revealed healthy bone without sig n ifica n t resorption
peripheral metal was exposed and lay outside the tissue from the anterior abut m ent back. Surprisingly, there was no discernible m ovem ent o f the implant on application o f m oderate pressure to the abutments. A roentgenogram o f the right side con firmed the clinical finding o f exfoliation. From the space between metal and bone, w hich may have been exaggerated by the angulation, it was difficult to see how even the buccal portion o f the im plant could be covered with tissue and the im plant firmly fixed. T h e superstructure was retained by clasps w hich still fit so securely to the im plant abutments that removal o f the su perstructure was difficult. This unneces sarily tight fixation o f the superstructure, with the patient’ s chewing primarily on the left side during recent years, m ay have been a contributing factor in the exfoliat ing tendency o f the right side o f the im-
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plant; m oreover, the patient tended to form heavy calculus. T h ick calculus was apparent on the anterior lingual surface and the undersurface o f the superstruc ture. Since this im plant was hopeless, it was removed the next day. It was easy to re m ove on the right side but difficult on the left. A surprising finding was that a section o f bone had grown over the lingual periphery in the region o f the mandibular torus on the left side. Such a deposition o f bone over the im plant frame in various regions has been observed in other implants rem oved after three or more years. Considerable mutilation of tissue in removing an im plant is unavoid able. Because the substructure is encapsu lated in fibrous tissue, the m ucoperiosteum must be split. It cannot be elevated cleanly from the bone. Another im portant observation was that apparently norm al m ucosa was vis ible in a 15 by 15 m m . area under the left posterior abutment. Since this was rela tively healthy, it seems to confirm the supposition that epithelium invades the small resorbed regions frequently observed to form under im plant abutments after a num ber o f years. T his downgrowth may be the cause of, or an accom panying ef fect of, the bone resorption. Close examination o f the im plant sub structure after removal revealed not only calculus deposits around the necks o f the implant abutments but also stains and d e posits on and under the substructure framework near the abutment and rest penetrations. T his indicated that there had been seepage o f oral fluids into these regions and revealed the extent o f the pocket form ation. T h e metal was bright elsewhere, which seemed to indicate ab sence o f epithelial dow ngrow th or, at least, o f seeping o f oral fluids beyond the regions adjacent to the abutment. It must be remembered that this imF ig . 4 * (P a tie n t 3) A : Im plant denture substructure inserted A u g . 6, 1953. B: Seven years' postinser tion, im plant denture is c lin ic a lly sound with some loss o f tissue at the rig h t an terio r abutm ent. C : N ine years' postinsertion, th ere are no sig n ifica n t changes from two years b efo re. D : N ine years' postinsertion, roentgenogram reveals normal underlying bone w ithout sig n ifica n t resorption
BODINE . . . VOLUME 67, SEPTEMBER 1963 • 47/357
plant was not typical since the gingival tissue around all abutments was loose. T h e seepage may not occu r in m ore typi cal implants where the tissue is tight around the necks o f the abutment pene trations. Sections o f apparently healthy and o f abnormal tissue rem oved from around the abutments and sections o f the bone d e posited over the im plant periphery were examined by a pathologist (Fig. 1, E ) . All three specimens were lined with stratified squamous epithelium w hich was thick ened in many places. In the apparently healthy specimens o f tissue around the abutments, there was inflammatory infil tration ; in the abnormal specimens o f tis sue, severe inflammation. T h e inflamma tion was primarily in the superficial dermis and involved the lower portion o f the epidermis; there was n o malignancy. T h e section o f bon e had no abnormalities. This im plant probably should not be considered a com plete failure. It might be called a seven year partial success since the patient had seven years o f implant denture com fort after his years o f strug gle with ordinary dentures. His implant denture had appeared satisfactory under professional examinations for at least six years. Patient 2 • A 41 year old wom an re ceived her mandibular implant denture on M ay 10, 1955, just a few months after the previous patient. W hen I examined her on July 9 and 10, 1962, seven and a half years later, it was perfect. T h e patient was first seen about a year before the im plant was made, when she was wearing her lower denture which she had stuffed with cleansing tissue to re store lost vertical dimension. Since she changed the tissue several times daily, keeping it scrupulously clean, her mouth was healthy except for the com plete re sorption o f the residual ridge. T o give her temporary but immediate relief, her denture was supported with 7 mm . o f w ax on each side; then it was built up and corrected by several succes
sive self-curing resin relinings. For co m parison, duplicate dentures were made, one with C oe M asticator and one with Hardy Bladed posterior teeth. She wore the dentures alternately, keeping a diary o f her reactions. It soon becam e obvious that masticating com fort and efficiency were minimal. Six months later, a call was received from her physician. She had becom e de spondent, had been hospitalized and had lost 35 lb. In consultation with the psy chiatrist, it was concluded that her de spondency was related to her denture problems and that an im plant denture might be the key to her recovery. I was reluctant to undertake an implant den ture under these circumstances, but they wanted her to have encouragem ent and hope. A fter considerable consultation, she was told that, if she recovered her health and could be cleared fo r surgery, an implant denture w ould be attempted. She im proved and, on April 10, 1955, her implant denture was inserted; this was the last in a series o f 13 mandibular implant dentures m ade at Fort G ordon, Ga. between 1951 and 1955. T h e implant, our first made from a T hiokol rubber impression, fit the bone accurately (Fig. 2 ). T hiokol rubber was the first satisfac tory bone impression material, and today it is preferred for im plant bone impres sions.6 A loose-fitting immediate temporary superstructure was placed as a surgical splint and to maintain occlusion, along with an elastic head bandage to keep the splint in occlusion, limit edem a and sup port peripheral tissue. A fter two weeks, the tissue had healed with no secondary metal exposure. Since I was being transferred, her superstruc ture was rushed to com pletion, and I did not see her again for over seven years. In annual reports by mail during the interim, she insisted that her im plant was perfect and denied ever having any inflammation or irritation in her m outh. W hen she was seen next, her general health and spirits had remained excellent.
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F ig . 5 • [P a tie n t 4 ) L e ft: Three years a fte r insertion of patient's first im plant denture, the im plant is sa tisfa cto ry : a few months later, it had to be rem oved because of a break in the m etal substructure. R ig h t: Seven years a fte r insertion o f p atient's second im plant denture, conditions are fa irly satisfacto ry
She had been treated by a dentist only on ce during the seven years, at which time she was given a prophylaxis o f the im plant abutments. T h e occlusion had remained w ithout visible change, and there was n o discernible loss o f vertical dimension. W hen the implant superstructure, which she said had always been rather loose, was rem oved, the implant denture was perfect (Fig. 3, a b o v e ). T h e tissue was tight around the fou r abutments, and the gingival crevice appeared normal. T here was no secondary metal exposure or inflamed tissue. Roentgenograms re vealed healthy bone with the metal in close relationship to the bone without vis ible resorption or suggestion o f epithelial downgrowth (Fig. 3, b e lo w ). A fter the im plant superstructure had been left out overnight, a pressure indi cator showed some small areas o f slight pressure o f the superstructure on the un derlying m ucosa and other areas where there was about 1 mm. space between the denture and the tissue. A fter these small pressure areas were relieved, the super structure was relined with self-curing re lining material, after which it was again relieved, using pressure indicator, to be certain that there was n o pressure on the tissue and that all stress was transmitted to the im plant abutments. T h e clasps o f the superstructure fram e were tightened slightly, and the upper conventional den ture was relined.
It was impossible to find anything to criticize about this implant denture. Cer tainly, it had been accepted by the oral tissues, and there was n o condition from which to anticipate trouble in com ing years. This patient could expect a favor able prognosis for her im plant denture for many m ore years. Patient 3 • A 44 year old m an received our fifth bone impression m andibular im plant denture on Aug. 6, 1953 (Fig. 4, A .) Initial healing was excellent, al though the tissue was thin over the metal at the distolingual periphery near the mylohyoid ridge. W hen the patient returned fo r follow up examination two years later, his im plant was in good condition. T h e tissue still thinly covered the distolingual metal. This thinness o f tissue persisted without noticeable change fo r almost seven years. Seven years after insertion, the chroni cally thin tissue at the distolingual periph ery perforated. H e was treated by another dentist and, although there was slight re sorption o f tissue at the right anterior abutment, the implant was clinically healthy (Fig. 4, B ) . T h e section o f ex posed metal was cut from the lingual pe riphery, and the region healed without com plication. W hen I examined this patient on July 16, 1962, his im plant denture had been in place nine years, the longest o f those I examined in this group. T h e recession
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at the labial side o f the right anterior abutment was about the same as it had been tw o years before (Fig. 4, G.) T h e region at the distolingual periphery, where the metal had been cut o ff two years before, had healed and was as healthy as the rest o f his m outh. Roentgenogram s showed no com plica tion as a result o f this m odification and no evidence o f settling or bone resorp tion (Fig. 4, D ) . T h e im plant superstructure fit securely but not tightly. Other than moderate wear o f the acrylic resin teeth, the o c clusion had not changed, and there seemed n o loss o f vertical dimension. His maxillary denture and mandibular im plant superstructure were relined and the tissues relieved from superstructure pres sure. T his im plant denture was n ot in as g ood condition as the previous patient’s seven year old im plant; however, the de ficiencies were m inor, and there was
. VOLUME 67, SEPTEMBER 1963 • 49/359
nothing serious to affect the prognosis in the next few years. Patient 4 • A 23 year old man was par ticularly interesting because he had had two m andibular im plant dentures in the previous ten years. H e has hypopituitar ism, and com plete resorption o f his m ax illary and m andibular residual ridges had occurred when he was referred to us. His first im plant denture was our first bone impression implant, crudely made o f meshwork from a somewhat distorted m odeling plastic bone impression.2’ 5,7 It was inserted on April 26, 1952. In spite o f the technic, healing was u ncom pli cated, and it solved his difficult denture problem for three years (Fig. 5, le f t ). Three years after insertion, roentgeno grams revealed a com plete break in the implant substructure in front o f the right posterior abutment probably caused by a defect in the casting. T h e meshwork im plant was rem oved in M ay, 1955. O n
F ig . 6 • (P a tie n t 5) A : Meshwork im plant d enture using circum feren tial wire p rim ary fixation inserted Se p t. 25, 1952. B: Five years' postinsertion, im p lant is alm ost p e rfe ct. C : Ten years' postinsertion, there is slight loss of tissue a t an terio r abutm ents. D : Ten years' postinsertion, roentgenogram revealed m oderate bone resorption
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July 23, 1955, a technically im proved im plant denture was inserted. I examined this patient July 20, 1962, seven years after he had received his sec ond implant denture. Considering his endocrine imbalance and the p oor bone and soft tissues, this im plant denture may be considered suc cessful (Fig. 5, right) ; however, there were deficiencies. T here was a small ex posure o f metal on the right posterior side and a larger one on the left posterior side which had existed since insertion. Although the exposure on the left had grown slowly larger, there was no sup puration, and the tissue around it was healthy. T his patient had had little mandibular bone when he received his first implant ten years ago. Roentgenogram s revealed n o serious pathologic changes on the right side. O n the left, there was epi thelium under the exposed metal, and the space between the metal and the bone under the exposure was filled by m ucoperiosteum. Nonetheless, close examination showed good general oral health after seven years with his second implant denture. I f the three years o f his first implant are in cluded, he has had ten years o f implant denture com fort and efficiency. T h e p a tient was not aware o f deficiencies, and he considered his implant denture excel lent since he could eat well and was co m fortable. Although further deterioration m ay occur, it should be slow, and he should have at least a few m ore years o f satisfaction with his im plant denture. Patient 5 ' A 45 year old man, w ho re ceived our second bone impression im plant denture (Fig. 6, A ) on Sept. 25, 1952,2,3,8 was examined last summer by another prosthodontist. T his implant was the second o f only two m ade o f the cast screen mesh and had circumferential wir ing on each side for primary fixation. A t that time, we still were developing the implant technic. O n the fifth post operative day, the incision opened in the
anterior region and exposed the metal framework. Granulation tissue form ed rapidly through and over the meshwork. By two months, there was only a small spot o f metal exposed near the left an terior abutment. I next saw this patient on A pril 15, 1957, when his im plant denture was al most five years old. In spite o f the elem en tary technic and p oor initial healing, his m outh was healthy (Fig. 6, B ) . T h ere was only slight evidence that the metal had been exposed during the first few months. Roentgenograms showed norm al bone under the implant without change in posi tion or unfavorable reaction to the cir cumferential wiring. T his patient was examined on July 5, 1962, ten years after insertion (Fig. 6, C ) . T h e prosthodontist w h o examined him stated, “ T h e patient has been getting along fine with his im plant denture, but has lost some tissue around the abutments. I feel this is mainly due to his failure to maintain his oral hygiene. A fter thorough prophylaxis,' proper hom e care was reem phasized, and the dentures were equili brated. T his alleviated some o f the m u cous membrane irritation w hich was present.” Roentgenograms showed m oderate re sorption after ten years creating a small space under some o f the abutments (Fig. 6, D ) . T here was no reduction in co m fort and efficiency as shown by the pa tient’s statement in the follow -up o f April, 1962: “ I feel I have the masterpiece o f your profession; after ten years it is still perfect.” DISCUSSION
These five mandibular im plant dentures 7 to 10 years after insertion may or may not be typical o f implants in general; however, valid conclusions may be drawn. L ife E xpectancy o f Im plant D enture • W ith proper technic,6,9 successful im plant dentures can be m ade that will solve, fo r 7, 10 or m ore years, difficult
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com plete denture problems and give pa tients greater com fort and efficiency than can be expected from conventional m ucosa-supported dentures. Conventional dentures, even with proper borders, surgi cal extensions, magnetized teeth or im planted magnets cannot approach the im plant denture w hich uses the m andibu lar bone for support and stability. Some properly made implant dentures must be rem oved in as little as seven years; however, this does not indicate com plete failure, especially for patients in an im portant or difficult period of their lives. Some implant dentures are clinically perfect after 7 to 10 years and, fo r these, 15, 20 or more years o f implant life may be anticipated. M any implant dentures show some de terioration or deficiency after 7 to 10 years,10 which usually does not affect com fort or efficiency and is not im m edi ately unfavorable to implant prognosis. Some may fail after ten years, whereas others continue to serve satisfactorily, per haps with further slow deterioration, for m uch longer. T h e problem before those who con tinue to work with the implant denture is to im prove further basic technics,9,11’ 12 selection o f patients, follow -up care and oral hygiene so that the percentage o f implant dentures that fail in about seven years will be considerably decreased, and the percentage that are nearly perfect after 8, 10 and m ore years will be in creased substantially. R oentgenogram s • It is difficult to make clear roentgenograms because the opaque metal o f the im plant substructure and ac com panying elongation and distortion hide critical osseous regions. Perhaps the most useful technic is to use a film holder to place fast intraoral films vertically, parallel to and somewhat away from the implant abutments and to make longcone exposures at angles varying ( + ) 15, 0 and ( — ) 15 decrease from the hori zontal.
Im plant Oral Penetration • W ith tech nics and materials advocated today, the experienced implant dentist should have little difficulty in making the implant fit the bone accurately; however, after five or m ore years, a region o f bone resorption sometimes develops immediately under the im plant abutments. I suspect that, when this resorption is deeper than about 1 mm., there probably has been a dow ngrowth o f oral epithelium into the re gion. If the region is not too large and oral hygiene is good, the m ucosa may tightly grip the abutment, and the region may remain essentially healthy for 9, 10 or m ore years. I f oral debris seeps into the region with the deposition o f calculus on the buried metal, chronic irritation and inflamma tion will develop. Irrigations, antiseptics and better oral hygiene sometimes effect great improvement, but the condition tends to recur and may lead to gradual deterioration and eventual removal after seven or m ore years. N um ber o f Oral M ucosal Penetrations • Because o f the tendency to bone resorp tion, epithelial downgrowth and pocket form ation to develop around the oral penetrations o f some implants, the num ber o f penetrations becom es important. Use o f m ore than the minimum four abutments required for denture support and distribution o f stress probably is con traindicated. Secondary metal exposures which per sist after initial healing o r develop later can be considered factors which may lead to implant deterioration and must be eliminated or minimized by use o f proper technic. O ften metal exposures in im plants made before 1955 were caused by distortion in the m odeling plastic im pressions which developed when they were rem oved from m ylohyoid undercuts. Thus, the substructure did not fit the bone accurately and, on insertion, a space existed between the metal and the bone into which the overlying tissue contracted.
52/362 • T H E JO U R N A LO FT H E A M E R IC A N DENTAL ASSOCIATION
Table • Twenty-two mandibular implant dentures, 5 to 10 years after insertion Implant no. 1
Date inserted
Years in place
April, 1952
3 10
2
Sept., 1952
3
April, 1953
4
April, 1953
5
June, 1953
6
Aug., 1953
7
Patient evaluation
Professional evaluation
Removed March, 1955
3 y e a r failure
Excellent
G ood
Excellent
Fair
91/4
Excellent
G ood
9
Excellent
Good
9
Good
Good
Dec., 1953
5
Removed Sept., 1958
5 year limited succ
8
Jan., 1954
8
Removed N ov., 1961
8 year limited succ
9
April, 1954
Vh
Removed O ct., 1961
7 xh
10
July, 1954
A/ a
Died O ct., 1958
4 /4
9/2
year limited succ year success
11
Dec., 1954
7/2
Excellent
Fair
12
May, 1955
m
Excellent
Excellent
13
May, 1955
VA
Excellent
Good
14
July, 1955
7
Excellent
Fair
15
Dec.. 1955
6/2
Excellent
Excellent
16
May, 1956
6/4
Excellent
Good
17
Sept., 1956
6
Excellent
Excellent
18
Sept., 1956
6
Excellent
Good
19
Sept., 1956
6
Good
Good
20
March, 1957
5/4
Excellent
Good
21
April, 1957
5/4
Excellent
Excellent
22
Aug., 1957
5
Excellent
Good
Attachm ent of Superstructure to Im plant Abutm ents • In the five im plant dentures studied 7 to 10 years after insertion, the superstructure attachment to the im plant abutments was rather tight in the worst and loose in the most successful. In none o f the other three was the attach ment particularly tight. T igh t fixation, the kind that makes rem oval by straight vertical stress difficult, may be an im por tant factor in predisposing to bone resorp tion, pocket form ation, shifting o f the implant substructure, metal exposure and eventual exfoliation, especially if accom panied by traumatic occlusion or abnor mal habits o f mastication. Therefore, I believe that the super structure should be attached to the im
plant abutments by precision fitting, with or without clasps, to produce positive resistance to occlusal and lateral stresses, yet afford only the m inim um resistance to vertical removal required for com fort and efficiency.8 T h e problem o f h ow to provide space for clasp action w ithout irritating the tissue around the im plant abutments has been solved. First, the acrylic resin is cured tight against the clasp. A no. 558 fissure bur is used to free the clasp from the acrylic resin, leaving a small space. After the clasp has been adjusted to give the minimal retention required, the space is filled with self-curing soft denture re lining resin. This type o f resin remains slightly elastic indefinitely and will allow
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for clasp action while making the under surface o f the superstructure smooth and nonirritating to the tissue. Evaluation • In the 1962 follow -up o f 30 implant denture patients, 22 had implants made from bone impression which had been in place from 5 to 10 years (see ta b le ). Four o f these had been removed. O n e was a technical failure (breaking o f the substructure); three (13 per cent) were true failures. M oreover, these three removed after 5, 7 j/i and 8 years might be considered partial successes. O ne pa tient died from unrelated causes five years after receiving his implant. In conclusion, five patients who could not be treated adequately with mucosaborne dentures have obtained satisfaction with implant dentures for a minimum of seven and a half years. T w o already have had ten years o f im plant denture effi ciency and com fort; one, nine years, and one, seven years. Four can anticipate an indefinite numbers o f years m ore service from their implants. SUMMARY
Five randomly selected patients with mandibular im plant dentures that had been in place for from 7 to 10 years were examined during July, 1962. T heir his tories were reviewed and roentgenograms and photographs obtained. A ll patients reported com fort and efficiency greater than they had obtained from previous conventional dentures. Critical clinical and roentgenographic examination revealed various conditions. O ne patient’ s im plant denture was virtu ally perfect; three had m inor deficiencies not affecting com fort, efficiency or early prognosis, and one had serious deficiencies requiring removal. A small region o f bone resorption often developed under the abutments after 3 to 4 years, which m ay represent a downgrowth o f oral epithelium. It had little
effect on im plant prognosis since the tis sue generally remained clinically healthy, closely gripping the neck o f the abutment in to the 7 to 10 year period. Occasionally, oral fluids seeped into the region with lim ited oral debris and calculus deposition, slight inflammation o f the tissue and pos sible slow extension o f the region o f re sorption and downgrowth. T his had little or no effect on denture com fort and effi ciency. Serious deterioration developed in only one patient. Properly made m andibular implant dentures usually remain clinically healthy for at least seven years. Current evidence suggests that not m ore than four penetrating abutments or rests should be used and that the attach m ent o f the superstructure to the implant abutments should afford only minimal re sistance to removal by vertical force.
Presented as part of a panel "Four approaches to achieving stability of complete dentures" before the Section on Compiete Prosthodontics, one hundred and third annual meeting, American Dental Association, Miami Beach, Fla., October 31, 1962. ^Associate professor of prosthodontics, School of Den tistry, University of Puerto Rico, San Juan, Puerto Rico. 1. Bodine, R. L., Jr. History and development of im plant dentures. Estratto da: Atti Secondo Simpòsio Internazionale degli Impianti Allopléstici a Scopo Pròtesi, Ñapóles, Italy. 253-262 Feb. 1958. 2. Bodine, R. L., Jr . The mandibular subperiosteal implant denture. Estrátto da: Atti Secondo Simpòsio Internazionàle degli Impianti Alloplàstici a Scopo Prò tesi, Ñapóles, Italy. 87-107 Feb. 1958. 3. Bodine, R. L., Jr . Implant dentures: prosthodontic —favorable. J . Pros. Den. 10:1132 Nov.-Dec. I960. 4. Archer, W . H. Implant dentures; surgical—unfavor able—qualified. J . Pros. Den. 10:1127 Nov.-Dec. I960. 5. Bodine, R. L., Jr. Prosthodontic essentials and an evaluation of the mandibular subperiosteal implant den ture. J.A .D .A . 51:654 Dec. 1955. 6. Bodine, R. L., Jr. The implant denture bone im pression; preparations and technique. J . Implant Den. 4:22 Nov. 1957. 7. Bodine, R. L., Jr., and Kotch, R. L. Experimental subperiosteal dental implants. U .S . Armed Forces M. J . 4:441 March 1953. 8. Bodine, R. J ., Jr. Implant dentures today. J . Im plant Den. 4:22 May 1958. 9. Bodine, R. L., J r . Implant dentures. Practical Den tal Monographs, Chicago, Year Book Medical Publica tions, Inc. May 1958, p. 1-40. 10. Bodine, R. L., Jr . Co-report: Implant dentures. Internat. D. J . 8:371 June 1958. 11. Bodine, R. J ., Jr., and Kotch, R. L. Mandibular subperiosteal implant denture technique. J . Pros. Den. 4:396 May 1954. 12. Bodine, R. L., Jr., and Kotch, R. L. Perfected mandibular subperiosteal implant denture technic. New York D. J . 20:193 May 1954.