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Vertical alveolar bone changes related to overdenture abutment teeth
:F:‘
11: v
'I'll.
I?>
1.0 JI ; t 1 4 rl-ERFEI\
S. IIOWAII3
PAYNE
‘Vertical alveolar bone changes related to werdentwe abutment teeth Ray ,4. Walters, ll.‘D.S.* lJnive:-sity 3f Maryland Cental School, Baltimore, Md.
0
ne of the perplexing problems associated wit a complete d.enture patients is alveolar bone change or loss. Jt has been well documented in the literaturelm5 that .after 1he natural teeth are removed, alveolar bone undergoes structural changes. This change varies from patient to patient but the most dramatic changes appear to occur in the mandibular arch. Overlay denture :ala.cementon retained endodontically treated roots is an acceptledform of treatment to preserve alveolar bone.6a7The alveolar bone preserves the root in a comfortable and functional manner, and a continuity cd proprioceptive funl:tion to the masticatory system is maintained. The retained roots act as vertical stabilizers for the denture, not as retainers. The overdenture should have a pas#siverelation to the abutment teeth. The principles of resrstance to rotation of denture bases and the vertical loading of teeth have been described in the literature.* Healthy soft tissue must be established and maintained around the abutments through periodontal therapy. The patient must be instructed in proper home care and maintenance.9-” It has been observed clinically that there are bone changes associated with overdenture abutment teeth.” An understanding of these relative bone changes around overdenture abutments will facilitate diagnosis and prognosis. The purpose of this study was to use a radiographic: method to record changes in vertical bone dimension around overdenture abu.tment teeth, and then measure the relative change in these dimensions over a period 01 time. METHODS
AND MATERIAL
Twenty patients participated in this study. The group included nine men and 11 women, with ages ranging from 28 to 69 years, who were patients in the undergrad-
Supported in part by Biomedical Research Support Grant of the National Institutes of Heal .h Read before the American College of Prosthodontists, National Capital Area Section, Washington, D.C. *Assistant Professor, Department of Removable Prosthodontics. THE JOURNAL
OF PROSTHETIC
DENTISTRY
Fig. 1. Small alloy restorations at 3, 6, 9, and 12 o’clock Ipositions on tooth surface used for a repeatable ence.
refer-
uate clinic at the Dental School, University of Maryland. For most of the patients selected, the lower canines, No. 22 and No. 27, were chosen as abutments to support a mandibular complete denture. Four patients had one premolar and one canine, and one patient had a lateral incisor and canine retained as abutments. Abutment teeth were selected that could be maintained readily after the coronal portions of the teeth were sectioned. These teeth received periodontal and endodontic therapy. Optimal gingival health and a minimal pocket depth of 2 mm or less was attained. After the removal of the coronal part of the tooth and root canal treatment, amalgam alloy was condensed into the canal to a depth of 4 mm and then overbuilt to a dome shape. When the alloy obtained an intial set, it was smoothed over to blend the domed alloy into the root surface. Small preparations were placed in an axial direction with a No. 330 bur in the root surface in positions that were at 12, 3, 6, and 9 o’clock (Fig. 1). These preparations were filled with alloy, smoothed,13 and provided radiographic and visual reference points throughout the study. Radiographs of the abutment teeth were made at 3-month intervals. Measurements on the films were made from the most prominent (coronal) portion of the lateral alloy plug to the crest of the 309
WALTERS
Fig. 3. Simple positioning device with x-ray cone aiming arm in place on mandibular denture.
Fig. 2. Radiograph demonstrating lateral amalgam reference points on grid used for measurements.
alveolar bone (Fig. 2). Two measurements were recorded and averaged for each mesial and distal aspect. Measurements were made at 3-month intervals. The radiographic film was positioned in the same relationship each time. To accomplish this, the patient’s complete denture was lubricated with petroleum jelly. A mix of acrylic resin tray material (Ontray, Teledyne Dental Products, Elk Grove Village, Ill.) was prepared. When it reached the doughy stage, it was placed over the denture teeth and base. An X.C.P (Rinn Corp., Elgin, Ill.) film holder, which is ribbed, was positioned into the acrylic resin over one side of the film holder to fashion a mechanical lock. The other side was left open to position the rod of the film holder, which fits into the x-ray cone aiming device (Fig. 3). The aiming device was positioned to center the abutment tooth on the radiograph. The film holder was held in place until the acrylic resin tray material reached its initial set. The whole assembly was then placed in water until a final set was obtained. The assembly was removed from the water and the film holder with its acrylic resin base was separated from the denture. The base was trimmed and reseated on the
310
denture for stability and accuracy of fit. If the assembly was loose, it was relined to ensure stability. If two teeth in the same dental arch were involved, an assembly was fabricated for each individual region. It has been reported that fabrication of radiographic stents, using this technique, gave a high degree of accuracy and is significantly more accurate than simply handpositioning the film (ia < .Ol). Sakurai et a1.j4 demonstrated that if one investigator exposed, developed, and measured the radiographs, a consistent dimension was measured for each tooth. The average difference in the measurements with the standardized method over a period of time was 0.1 f 0.1 mm from 0 to 6 months. By hand-positioning the film, it was 0.4 * 0.4 mm from 0 to 6 months. An anterior radiographic film was positioned in the film holder and a grid (Henry Schein, Port Washington, N.Y.) was interposed on the film’5,‘6 (Fig. 4). The rod was placed in the film holder and the denture inserted. The cone, with its aiming device, was attached to the film holder rod and its assembly. The patient was instructed to close lightly on the assembly to stabilize it during the exposure (Fig. 5). A setting of 70 kilovolt (peak), 15 mA/s, and 30 pulses was used for the exposure of D speed film. Routine processing was done. The following steps were accomplished for denture placement: All blebs and sharp edges were removed. The complete denture was coated on its internal surface with pressure-indicating paste, seated, and relieved as necessary. The borders were adjusted by using disclosing wax. The occlusion was refined to a proven centric-relation articulator mounting, and the patient was given the dentures. The prepared overdenture abutments were refitted to the denture base by relining with Jet (Lang Dental Mfg. Co., Chicago, Ill.) tooth-colored acrylic resin after 1 week. Pressure-indicating paste was again used.
MARCH
1987
VOLUME
57
NUMBER
3
VERTICAL
ALVEOLAR
BONE CHANGES
Fig. 4. Everett-Fixot grids with a piece of lead foil on one to keep right and left side radiographs identifiable.
All pressure spots were relieved until the paste indicated uniform contact over the primary bearing surface of the edentulous ridge and the top surface of the retained root. The denture base around the gingival sulcus was relieved so there was no impingement. A clinical remount was performed on each patient to perfect the occlusion through selective grinding of the teeth. Home care instructions regarding denture and abutment care were reviewed with each patient. A photographic record was made and each patient was instructed to place one drop of 0.4% stannous fluoride ge117 in each denture abutment depression of the denture base once a day each morning after cleaning the denture according to instructions. Patients were recalled at 3-month intervals for 1 year after denture insertion. All photographs, radiographs, and measurements were made by the principal investigator. Two radiographs were made on each patient. One film was placed on file. The other radiograph was measured under a magnifying glass by using optical loupes and illuminated background. The data were recorded and placed in a file. Two weeks later, the filed radiograph was measured in the same manner. The results were recorded on a separate data sheet. In a comparison between the recordings made on the two films, the difference between the two was less than 0.1 mm in all films. RESULTS The results are listed in Table I. Results of one-way analysis of variance and Duncan’s multiple range test
THE JOURNAL
OF PROSTHETIC
DENTISTRY
Fig. 5. Positioning assembly with radiographic film and grid affixed in patient’s mouth before film exposure.
indicated that the 3-, 6, 9-, and 12-month postinsertion bone levels on the mesial side of tooth No. 22 (n = 19) were not significantly different from the initial insertion measurements (F = 1.865; p > .05). Differences on the mesial side of tooth No. 27 (n = 17) were also nonsignificant with a value of F = 1.726; p > .05 (Fig. 6). On tooth No. 22 (n = 19) and tooth No. 27 (n = 17), significant differences were found on the distal surfaces between the initial insertion measurement and the additional 3-month recording periods (F = 2.583; p < .05 and F = 4.026; p < .Ol, respectively) (Fig. 7). On tooth No. 22, distal measurements made at the 6-, 9-, and 1Zmonth periods showed a significant difference in
311
WALTERS
0.3 0.2 0.1 RELATIVE CHANGE (mm) (avg)
0.0 -0.1
yfgyEF
-0.3 -0.4
-0.2
-0.5 -0.6 -0.7 -0.6 -0.9 -1.0 TIME
3 MOS
6 MOS
9 MOS
+22-o
12 MOS
#27-e
6. Changes in millimeters of bone level of mesial side of teeth No. 22 and No. 27 over a l-year period.
Fig.
Table I. Mean bone level change Time (mod 6
3 Tooth
No.
22M 22D 27M 27D
PremolarsM PremolarsD
12
9
n
Mean
SD
Mean
SD
Mean
SD
Mean
SD
19 19 17 17 4 4
-0.05 -0.24 -0.14 -0.00 -0.63 -0.10
0.32 0.50 0.40 0.54 0.85 0.16
-0.16 -0.35 -0.25 -0.22 -0.55 0.00
0.37 0.53 0.42 0.27 0.97 0.20
-0.25 -0.43 -0.30 -0.28 -0.50 0.15
0.57 0.57 0.52 0.47 1.17 0.31
-0.34 -0.41 -0.35 -0.45 -0.45 0.40
0.62 0.50 0.59 0.38 1.13 0.80
M = mesialside;D = distal side. relative bone loss compared with initial insertion and 3-month measurements. On tooth No. 27, a significant difference in distal bone loss was seen only at the 12-month period (Table I). In a comparison of figures for the five recording-time periods of 0, 3, 6, 9, and 12 months, the mesial and the distal surfaces of the premolars (n = 4) in this small sample showed no significant differences (F = 0.280; p > .05 and F = 0.946; p > .05, respectively) (Fig. 8). DISCUSSION Radiographically, little bone change was noted in the first 3 months after denture insertion. A range of relative bone changes of approximately 0.2 and 0.4 mm occurred after 6 months in 75% of the patients. Some of the changes observed were of an increased bone level. This apparent response may have resulted from an extrusion of the abutment teeth or a wearing of the internal surface of the acrylic resin denture base over the abutments. A
312
combination of both factors could be involved. The distal aspects of teeth No. 22 and No. 27 demonstrated more negative changes than the mesial aspects. The forward and upward displacement of the denture base as it settles has a detrimental effect on the bone levels on the distal surfaces of the abutments.12 Where premolars were retained, bone changes were minimal or nonexistent. This might indicate a bone increase or that the denture intruded the root. Because of the small sample (n = 5), conclusive results are not available. The study does show that there are rapid bone changes around overdenture abutments under certain circumstances. Dramatic changes can occur in a short period if the patient’s oral home care is not monitored closely, 0.4% SnF12 gel is not used once a day on the abutments, or the occlusion of the dentures is not maintained during the first 4 to 6 months. The occlusion of the overdentures was monitored closely. Only one
MARCH
1987
VOLUME
57
NUMBER
3
VERTICAL
ALVEOLAR
BONE CHANGES
0.3 0.2 0.1 0.0
RELATIVE CHANGE
(mm)
-0.1
(a4
-0.2
-0.5 -0.6 -0.7 -0.6 -0.9
TIME
3 MOS
6 MOS
12 MOS
*27-e
*22-o
Fig. 7. Changes in millimeters over a l-year period.
9 MOS
of bone level of distal side of teeth No. 22 and No. 27
0.7 0.6 0.5 0.4
RELATIVE CHANGE
0.3
(mm) (avg) OF PREMOLARS
0.2 0.1 0.0 -0.1 -0.2 -0.3 -0.4 -0.5 -0.6 TIME
MESIAL
Fig. 8. Changes period.
in millimeters
of bone
patient had sufficient occlusal changes to warrant a denture remount after 9 months. The other patients exhibited some occlusal changes, but it was felt that these were not detrimental to the study. There appeared to be a direct connection between sulcular plaque accumulation and bone changes. There also appeared to be an inverse relation between the use of the fluoride drops and plaque accumulation. Plaque accumulation equates to gingival inflammation.6 Settling of the denture could result in occlusal
THE JOURNAL
OF PROSTHETIC
DENTISTRY
6 MOS
3 MOS
0
9 MOS
DISTAL
level
of retainer
12 MOS
@
premolars
over a l-year
disharmony and a shifting of position in relation to the abutments. A combination of tissue inflammation and denture base shifting appeared to contribute to the patterns of bone change. Recalls are continuing. A relatively small sample (20) of overdenture patients was followed up in this study. The technique was reliable for obtaining data on changes in bone levels of overdenture abutment teeth. Methods should be used to monitor tooth extrusion/depression and denture base wear of the surface opposing the abutments during the
313
WALTERS
course of observation. In addition, the effect of the anterior-posterior rock of the denture base needs to be addressed.
CONCLUSIONS The results of this investigation show that although overdentures are used extensively as a treatment modality, dentists should be aware of patterns of bone changes on abutment. roots. Patients should be placed on a routine recall at 3-month intervals and their periodontal health closely monitored. Plaque accumulation appeared to have an adverse effect on the integrity of the attached gingivae of the retained roots. The occlusion of the overdentures should be monitored closely and if significant occlusal changes are noted, the dentures should be remounted on the articulator by using new interocclusal records. Denture base shifting should be reduced to a minimum to maintain the desired occlusion. This may be necessary 4 to 6 months after insertion. Occlusal changes may have a detrimental effect on the longevity of treatment. If recalls are carried out, the dentist can, with a degree of confidence, inform the patient that the treatment will provide a favorable prognosis. REFERENCES 1. Atwood DA. Some clinical factors related to rate of resorption of residual ridges. J PROSTHETDENT 1962;12:441-50. 2. Tallgren A Positional changes of complete dentures. A 7-year longitudinal study. Acta Odontol Stand 1969;27:539-61. 3. Tallgren A The continuing reduction of the residual alveolar ridges in complete denture wearers. A mixed-longitudinal study covering 25 years. J PROSTHETDENT 1972;27:120-132. 4. Carlsson GE, Persson G. Morphologic changes of the mandible after extraction and wearing of dentures. Sven Tandlak Tidske 1970;63:219-32.
314
5. 6. 7.
8. 9.
10.
11.
12. 13.
14.
15. 16.
17.
Schei 0, Waerhaug J, Lovdal A, Arno A. Alveolar bone loss as related to oral hygiene and age. J Periodontol 1959;30:7-16. Leuck MH, LaVelle WE. Preservation of the mandibular ridge through root retention. J Acad Gen Dent 1973;21:29-32. Morrow RM, Powell JM, Jameson WS, Jewson LG, Rudd KD. Tooth-supported complete dentures. Description and clinical evaluation of a simplified technique. J PROSTHET DENT 1969;22:414-24. Miller PA. Complete dentures supported by natural teeth. J PROSTHETDENT 1958;8:924-8. Toolson LB, Smith OE. A 2-year longitudinal study of overdenture patients. Part I: Incidence and control of caries on overdenture abutments. J PROSTHETDENT 1978;40:486-91. Toolson LB, Smith OE, Phillips C. A 2-year longitudinal study of overdenture patients. Part II: Assessment of periodontal health of overdenture abutments. J PROSTHETDENT 1982;47:4-11. Silness J, Loe H. Periodontal disease in pregnancy. II. Correlation between oral hygiene and periodontal condition. Acta Odontol Stand 1964;22:121. Crum RJ, Rooney GE. Alveolar bone loss in overdentures: a S-year study. J PROSTHETDENT 1978;40:610-13. Renner RP, Gomes BC, McNamara TF, Baer PN, Shakun ML. Overdenture sequelae: a nine-month report. J PROSTHETDENT 1982;48:377-84. Sakurai K, Arbree N, Galovic G. Radiographic assessment of the overdenture tooth and its periodontium [Abstract]. J Dent Res 1986;65(Special issue):250. Everett FG, Fixott HC. Use of an incorporated grid in the diagnosis of oral roetgenograms. Oral Surg 1963;16:1061-4. Fixott HC, Everett FG, Watkins RF. Refinements in diagnostic x-ray technics with the use of wire grids. J Am Dent Assoc 1969;78:122-5. Derkson GD, MacEntee MM. Effect of 0.4% stannous fluoride gel on the gingival health of overdenture abutments. J PROSTHET DENT 1982;48:23-6.
Reprint requeststo: DR. RAY A. WALTERS UNIVERSI~ OF MARYLAND DENTAL SCHOLL BALTIMORE, MD 21201-1586
MARCH 1987
VOLUME 57
NUMBER 3
11: v
'I'll.
I?>
1.0 JI ; t 1 4 rl-ERFEI\
S. IIOWAII3
PAYNE
‘Vertical alveolar bone changes related to werdentwe abutment teeth Ray ,4. Walters, ll.‘D.S.* lJnive:-sity 3f Maryland Cental School, Baltimore, Md.
0
ne of the perplexing problems associated wit a complete d.enture patients is alveolar bone change or loss. Jt has been well documented in the literaturelm5 that .after 1he natural teeth are removed, alveolar bone undergoes structural changes. This change varies from patient to patient but the most dramatic changes appear to occur in the mandibular arch. Overlay denture :ala.cementon retained endodontically treated roots is an acceptledform of treatment to preserve alveolar bone.6a7The alveolar bone preserves the root in a comfortable and functional manner, and a continuity cd proprioceptive funl:tion to the masticatory system is maintained. The retained roots act as vertical stabilizers for the denture, not as retainers. The overdenture should have a pas#siverelation to the abutment teeth. The principles of resrstance to rotation of denture bases and the vertical loading of teeth have been described in the literature.* Healthy soft tissue must be established and maintained around the abutments through periodontal therapy. The patient must be instructed in proper home care and maintenance.9-” It has been observed clinically that there are bone changes associated with overdenture abutment teeth.” An understanding of these relative bone changes around overdenture abutments will facilitate diagnosis and prognosis. The purpose of this study was to use a radiographic: method to record changes in vertical bone dimension around overdenture abu.tment teeth, and then measure the relative change in these dimensions over a period 01 time. METHODS
AND MATERIAL
Twenty patients participated in this study. The group included nine men and 11 women, with ages ranging from 28 to 69 years, who were patients in the undergrad-
Supported in part by Biomedical Research Support Grant of the National Institutes of Heal .h Read before the American College of Prosthodontists, National Capital Area Section, Washington, D.C. *Assistant Professor, Department of Removable Prosthodontics. THE JOURNAL
OF PROSTHETIC
DENTISTRY
Fig. 1. Small alloy restorations at 3, 6, 9, and 12 o’clock Ipositions on tooth surface used for a repeatable ence.
refer-
uate clinic at the Dental School, University of Maryland. For most of the patients selected, the lower canines, No. 22 and No. 27, were chosen as abutments to support a mandibular complete denture. Four patients had one premolar and one canine, and one patient had a lateral incisor and canine retained as abutments. Abutment teeth were selected that could be maintained readily after the coronal portions of the teeth were sectioned. These teeth received periodontal and endodontic therapy. Optimal gingival health and a minimal pocket depth of 2 mm or less was attained. After the removal of the coronal part of the tooth and root canal treatment, amalgam alloy was condensed into the canal to a depth of 4 mm and then overbuilt to a dome shape. When the alloy obtained an intial set, it was smoothed over to blend the domed alloy into the root surface. Small preparations were placed in an axial direction with a No. 330 bur in the root surface in positions that were at 12, 3, 6, and 9 o’clock (Fig. 1). These preparations were filled with alloy, smoothed,13 and provided radiographic and visual reference points throughout the study. Radiographs of the abutment teeth were made at 3-month intervals. Measurements on the films were made from the most prominent (coronal) portion of the lateral alloy plug to the crest of the 309
WALTERS
Fig. 3. Simple positioning device with x-ray cone aiming arm in place on mandibular denture.
Fig. 2. Radiograph demonstrating lateral amalgam reference points on grid used for measurements.
alveolar bone (Fig. 2). Two measurements were recorded and averaged for each mesial and distal aspect. Measurements were made at 3-month intervals. The radiographic film was positioned in the same relationship each time. To accomplish this, the patient’s complete denture was lubricated with petroleum jelly. A mix of acrylic resin tray material (Ontray, Teledyne Dental Products, Elk Grove Village, Ill.) was prepared. When it reached the doughy stage, it was placed over the denture teeth and base. An X.C.P (Rinn Corp., Elgin, Ill.) film holder, which is ribbed, was positioned into the acrylic resin over one side of the film holder to fashion a mechanical lock. The other side was left open to position the rod of the film holder, which fits into the x-ray cone aiming device (Fig. 3). The aiming device was positioned to center the abutment tooth on the radiograph. The film holder was held in place until the acrylic resin tray material reached its initial set. The whole assembly was then placed in water until a final set was obtained. The assembly was removed from the water and the film holder with its acrylic resin base was separated from the denture. The base was trimmed and reseated on the
310
denture for stability and accuracy of fit. If the assembly was loose, it was relined to ensure stability. If two teeth in the same dental arch were involved, an assembly was fabricated for each individual region. It has been reported that fabrication of radiographic stents, using this technique, gave a high degree of accuracy and is significantly more accurate than simply handpositioning the film (ia < .Ol). Sakurai et a1.j4 demonstrated that if one investigator exposed, developed, and measured the radiographs, a consistent dimension was measured for each tooth. The average difference in the measurements with the standardized method over a period of time was 0.1 f 0.1 mm from 0 to 6 months. By hand-positioning the film, it was 0.4 * 0.4 mm from 0 to 6 months. An anterior radiographic film was positioned in the film holder and a grid (Henry Schein, Port Washington, N.Y.) was interposed on the film’5,‘6 (Fig. 4). The rod was placed in the film holder and the denture inserted. The cone, with its aiming device, was attached to the film holder rod and its assembly. The patient was instructed to close lightly on the assembly to stabilize it during the exposure (Fig. 5). A setting of 70 kilovolt (peak), 15 mA/s, and 30 pulses was used for the exposure of D speed film. Routine processing was done. The following steps were accomplished for denture placement: All blebs and sharp edges were removed. The complete denture was coated on its internal surface with pressure-indicating paste, seated, and relieved as necessary. The borders were adjusted by using disclosing wax. The occlusion was refined to a proven centric-relation articulator mounting, and the patient was given the dentures. The prepared overdenture abutments were refitted to the denture base by relining with Jet (Lang Dental Mfg. Co., Chicago, Ill.) tooth-colored acrylic resin after 1 week. Pressure-indicating paste was again used.
MARCH
1987
VOLUME
57
NUMBER
3
VERTICAL
ALVEOLAR
BONE CHANGES
Fig. 4. Everett-Fixot grids with a piece of lead foil on one to keep right and left side radiographs identifiable.
All pressure spots were relieved until the paste indicated uniform contact over the primary bearing surface of the edentulous ridge and the top surface of the retained root. The denture base around the gingival sulcus was relieved so there was no impingement. A clinical remount was performed on each patient to perfect the occlusion through selective grinding of the teeth. Home care instructions regarding denture and abutment care were reviewed with each patient. A photographic record was made and each patient was instructed to place one drop of 0.4% stannous fluoride ge117 in each denture abutment depression of the denture base once a day each morning after cleaning the denture according to instructions. Patients were recalled at 3-month intervals for 1 year after denture insertion. All photographs, radiographs, and measurements were made by the principal investigator. Two radiographs were made on each patient. One film was placed on file. The other radiograph was measured under a magnifying glass by using optical loupes and illuminated background. The data were recorded and placed in a file. Two weeks later, the filed radiograph was measured in the same manner. The results were recorded on a separate data sheet. In a comparison between the recordings made on the two films, the difference between the two was less than 0.1 mm in all films. RESULTS The results are listed in Table I. Results of one-way analysis of variance and Duncan’s multiple range test
THE JOURNAL
OF PROSTHETIC
DENTISTRY
Fig. 5. Positioning assembly with radiographic film and grid affixed in patient’s mouth before film exposure.
indicated that the 3-, 6, 9-, and 12-month postinsertion bone levels on the mesial side of tooth No. 22 (n = 19) were not significantly different from the initial insertion measurements (F = 1.865; p > .05). Differences on the mesial side of tooth No. 27 (n = 17) were also nonsignificant with a value of F = 1.726; p > .05 (Fig. 6). On tooth No. 22 (n = 19) and tooth No. 27 (n = 17), significant differences were found on the distal surfaces between the initial insertion measurement and the additional 3-month recording periods (F = 2.583; p < .05 and F = 4.026; p < .Ol, respectively) (Fig. 7). On tooth No. 22, distal measurements made at the 6-, 9-, and 1Zmonth periods showed a significant difference in
311
WALTERS
0.3 0.2 0.1 RELATIVE CHANGE (mm) (avg)
0.0 -0.1
yfgyEF
-0.3 -0.4
-0.2
-0.5 -0.6 -0.7 -0.6 -0.9 -1.0 TIME
3 MOS
6 MOS
9 MOS
+22-o
12 MOS
#27-e
6. Changes in millimeters of bone level of mesial side of teeth No. 22 and No. 27 over a l-year period.
Fig.
Table I. Mean bone level change Time (mod 6
3 Tooth
No.
22M 22D 27M 27D
PremolarsM PremolarsD
12
9
n
Mean
SD
Mean
SD
Mean
SD
Mean
SD
19 19 17 17 4 4
-0.05 -0.24 -0.14 -0.00 -0.63 -0.10
0.32 0.50 0.40 0.54 0.85 0.16
-0.16 -0.35 -0.25 -0.22 -0.55 0.00
0.37 0.53 0.42 0.27 0.97 0.20
-0.25 -0.43 -0.30 -0.28 -0.50 0.15
0.57 0.57 0.52 0.47 1.17 0.31
-0.34 -0.41 -0.35 -0.45 -0.45 0.40
0.62 0.50 0.59 0.38 1.13 0.80
M = mesialside;D = distal side. relative bone loss compared with initial insertion and 3-month measurements. On tooth No. 27, a significant difference in distal bone loss was seen only at the 12-month period (Table I). In a comparison of figures for the five recording-time periods of 0, 3, 6, 9, and 12 months, the mesial and the distal surfaces of the premolars (n = 4) in this small sample showed no significant differences (F = 0.280; p > .05 and F = 0.946; p > .05, respectively) (Fig. 8). DISCUSSION Radiographically, little bone change was noted in the first 3 months after denture insertion. A range of relative bone changes of approximately 0.2 and 0.4 mm occurred after 6 months in 75% of the patients. Some of the changes observed were of an increased bone level. This apparent response may have resulted from an extrusion of the abutment teeth or a wearing of the internal surface of the acrylic resin denture base over the abutments. A
312
combination of both factors could be involved. The distal aspects of teeth No. 22 and No. 27 demonstrated more negative changes than the mesial aspects. The forward and upward displacement of the denture base as it settles has a detrimental effect on the bone levels on the distal surfaces of the abutments.12 Where premolars were retained, bone changes were minimal or nonexistent. This might indicate a bone increase or that the denture intruded the root. Because of the small sample (n = 5), conclusive results are not available. The study does show that there are rapid bone changes around overdenture abutments under certain circumstances. Dramatic changes can occur in a short period if the patient’s oral home care is not monitored closely, 0.4% SnF12 gel is not used once a day on the abutments, or the occlusion of the dentures is not maintained during the first 4 to 6 months. The occlusion of the overdentures was monitored closely. Only one
MARCH
1987
VOLUME
57
NUMBER
3
VERTICAL
ALVEOLAR
BONE CHANGES
0.3 0.2 0.1 0.0
RELATIVE CHANGE
(mm)
-0.1
(a4
-0.2
-0.5 -0.6 -0.7 -0.6 -0.9
TIME
3 MOS
6 MOS
12 MOS
*27-e
*22-o
Fig. 7. Changes in millimeters over a l-year period.
9 MOS
of bone level of distal side of teeth No. 22 and No. 27
0.7 0.6 0.5 0.4
RELATIVE CHANGE
0.3
(mm) (avg) OF PREMOLARS
0.2 0.1 0.0 -0.1 -0.2 -0.3 -0.4 -0.5 -0.6 TIME
MESIAL
Fig. 8. Changes period.
in millimeters
of bone
patient had sufficient occlusal changes to warrant a denture remount after 9 months. The other patients exhibited some occlusal changes, but it was felt that these were not detrimental to the study. There appeared to be a direct connection between sulcular plaque accumulation and bone changes. There also appeared to be an inverse relation between the use of the fluoride drops and plaque accumulation. Plaque accumulation equates to gingival inflammation.6 Settling of the denture could result in occlusal
THE JOURNAL
OF PROSTHETIC
DENTISTRY
6 MOS
3 MOS
0
9 MOS
DISTAL
level
of retainer
12 MOS
@
premolars
over a l-year
disharmony and a shifting of position in relation to the abutments. A combination of tissue inflammation and denture base shifting appeared to contribute to the patterns of bone change. Recalls are continuing. A relatively small sample (20) of overdenture patients was followed up in this study. The technique was reliable for obtaining data on changes in bone levels of overdenture abutment teeth. Methods should be used to monitor tooth extrusion/depression and denture base wear of the surface opposing the abutments during the
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course of observation. In addition, the effect of the anterior-posterior rock of the denture base needs to be addressed.
CONCLUSIONS The results of this investigation show that although overdentures are used extensively as a treatment modality, dentists should be aware of patterns of bone changes on abutment. roots. Patients should be placed on a routine recall at 3-month intervals and their periodontal health closely monitored. Plaque accumulation appeared to have an adverse effect on the integrity of the attached gingivae of the retained roots. The occlusion of the overdentures should be monitored closely and if significant occlusal changes are noted, the dentures should be remounted on the articulator by using new interocclusal records. Denture base shifting should be reduced to a minimum to maintain the desired occlusion. This may be necessary 4 to 6 months after insertion. Occlusal changes may have a detrimental effect on the longevity of treatment. If recalls are carried out, the dentist can, with a degree of confidence, inform the patient that the treatment will provide a favorable prognosis. REFERENCES 1. Atwood DA. Some clinical factors related to rate of resorption of residual ridges. J PROSTHETDENT 1962;12:441-50. 2. Tallgren A Positional changes of complete dentures. A 7-year longitudinal study. Acta Odontol Stand 1969;27:539-61. 3. Tallgren A The continuing reduction of the residual alveolar ridges in complete denture wearers. A mixed-longitudinal study covering 25 years. J PROSTHETDENT 1972;27:120-132. 4. Carlsson GE, Persson G. Morphologic changes of the mandible after extraction and wearing of dentures. Sven Tandlak Tidske 1970;63:219-32.
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Schei 0, Waerhaug J, Lovdal A, Arno A. Alveolar bone loss as related to oral hygiene and age. J Periodontol 1959;30:7-16. Leuck MH, LaVelle WE. Preservation of the mandibular ridge through root retention. J Acad Gen Dent 1973;21:29-32. Morrow RM, Powell JM, Jameson WS, Jewson LG, Rudd KD. Tooth-supported complete dentures. Description and clinical evaluation of a simplified technique. J PROSTHET DENT 1969;22:414-24. Miller PA. Complete dentures supported by natural teeth. J PROSTHETDENT 1958;8:924-8. Toolson LB, Smith OE. A 2-year longitudinal study of overdenture patients. Part I: Incidence and control of caries on overdenture abutments. J PROSTHETDENT 1978;40:486-91. Toolson LB, Smith OE, Phillips C. A 2-year longitudinal study of overdenture patients. Part II: Assessment of periodontal health of overdenture abutments. J PROSTHETDENT 1982;47:4-11. Silness J, Loe H. Periodontal disease in pregnancy. II. Correlation between oral hygiene and periodontal condition. Acta Odontol Stand 1964;22:121. Crum RJ, Rooney GE. Alveolar bone loss in overdentures: a S-year study. J PROSTHETDENT 1978;40:610-13. Renner RP, Gomes BC, McNamara TF, Baer PN, Shakun ML. Overdenture sequelae: a nine-month report. J PROSTHETDENT 1982;48:377-84. Sakurai K, Arbree N, Galovic G. Radiographic assessment of the overdenture tooth and its periodontium [Abstract]. J Dent Res 1986;65(Special issue):250. Everett FG, Fixott HC. Use of an incorporated grid in the diagnosis of oral roetgenograms. Oral Surg 1963;16:1061-4. Fixott HC, Everett FG, Watkins RF. Refinements in diagnostic x-ray technics with the use of wire grids. J Am Dent Assoc 1969;78:122-5. Derkson GD, MacEntee MM. Effect of 0.4% stannous fluoride gel on the gingival health of overdenture abutments. J PROSTHET DENT 1982;48:23-6.
Reprint requeststo: DR. RAY A. WALTERS UNIVERSI~ OF MARYLAND DENTAL SCHOLL BALTIMORE, MD 21201-1586
MARCH 1987
VOLUME 57
NUMBER 3