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Retentive dentures for patients with mutilated jaws
Retentive dentures for patients with mutilated jaws Ellsworth K. Kelly,* DDS, S an F ra n cisco
In co n stru ctin g c o m p le te den tu res fo r p a t ie n ts w ith m u ti la te d ja w s, t h e m a in basis f o r s u c c e s s is th a t t h e p r o c e d u r e s g o v e r n i n g r e te n ti o n o f d e n t u r e s in a n y p a t ie n t b e f o l l o w e d ca r e fu lly . S p e cifica lly , b o th m axillary a n d m a n d ib u la r d e n t u r e s u su ally lack s u ffic ie n t c o v e r a g e in t h e p o s t erio r p a rt o f t h e m o u t h , a n d m o r e a t t e n tion s h o u l d b e g i v e n to t h e c o n t o u r i n g o f p o l i s h e d su rfa ce s. S u r g ic a l c o r r e c t i o n a n d s p e c i a l d e n tu r es , s u c h as h o l l o w m axillary d e n tu r e s , i m p r o v e d e n t u r e t o l e r a n c e in s o m e instances.
1 ’he term mutilated jaw includes exten sive loss of bony support. The loss of normal denture base support may result from extreme resorption of the alveolar process, from surgical removal of the supporting tissue to eradicate a malig nancy, from extensive traumatic loss or from a congenital lack of tissue as in the cleft palate. The term maxillofacial also is used to describe these losses. Patients with mutilated jaws have a problem in denture retention that sometimes can be met with special procedures. Especially, however, the problem requires faithful
adherence to those basic technical proce dures governing retention and stability that all patients obtaining complete den tures should, but frequently do not, re ceive. Retention and stability are two terms applied to express one quality—the ability of the dentures to remain in place against the basal seat. Recent research and thinking on this topic emphasize function rather than a static situation. The denture movements during mastica tion have been studied by Sheppard1 and others, using cinefluoroscopy. They found that even the best-fitting dentures move considerably during function and are made tolerable only by the patient’s mus cular control in reseating them. Brill2 has recently called attention to the role of neuromuscular control by the patient in retaining the dentures during function. These observations do not lessen the im portance of good fit in dentures; rather, they add further requirements of denture technic. The polished surfaces of the den ture must be contoured to facilitate the control of the dentures by the tongue and cheek muscles. The impression surface of the lower denture must be smooth to allow it to move in function without ir ritating the mucosa.
1420 • J . A M E R . D E N T . A S S N .: V o l. 71, D e c. 1765
DENTURE BASE FORM AND EXTENSION It is generally agreed that maximum sta bility in complete dentures is obtained with close adaptation of the base to the tissues, coverage of as large an area as permitted by the anatomic form of the mouth and a firm peripheral seal.3’6 Re gardless of the technic or materials used; knowledge of the anatomy of the area is most important. In the maxillary den ture, the most common fault is an over or under extension at the posterior bor der. The posterior border includes not only that region commonly called the postdam region where the hard palate meets the soft palate, it includes the lat eral region where the denture border ex tends through the hamular notch and curves up behind and lateral to the tu berosity to gain the height of the denture flange. This region, extending from the hamular notch to the height of the flange, is extremely important from the stand point of denture seal. It should be termed the internal pterygoid region because it is limited by a slip of the internal pterygoid muscle that originates on the distal and lateral aspect of the tuberosity, far exter nal to the principal origin of the muscle. When properly extended in this region, the denture border assumes a characteris tic double curvature on the medial edge of a flattened, rather wide border. In the hamular notch area, the den ture is often underextended because the notch is often quite a few millimeters distal to the termination of the tuberosity. The notch should be palpated to deter mine the extent of the denture in this region. The posterior border should terminate at the vibrating line. It is difficult to understand why so many dentures are underextended in this region when the demarcating, movable tissue is so easily demonstrated. It can only be assumed that the extent of the denture is often determined on a cast in the laboratory without reference to the patient’s mouth. The most common error in the com
plete lower denture is a failure to extend the denture base distally, both distobuccally and distolingually, as well as over the retromolar pad. The denture base must completely cover the pad, extending lingually into the depression that lies lin gual and inferior to the pad and as far distal in this area as the palatoglossus muscle permits. On the buccal aspect, the distal border conforms to the attachment of the masseter and extends buccally to the termination of the masseter muscle. This region, which Boucher7 calls the buccal shelf area, furnishes excellent sup port, and the lower denture should be widest at this point. The shape, formed by muscle attachments to the mandible, is characteristic regardless of the amount of alveolar ridge resorption that has taken place. A second region where many lower dentures are deficient is the an terior lingual region. Here, the thickness of the denture border will help attain a seal when the depth of flange is limited. The flange in this region should be as wide as the location of the openings of the sublingual glands in the plica sub lingualis permit. When there is almost complete resorption of the alveolar proc ess, the genial tubercle appears as a rounded bony prominence in this region. This is a dense, unchangeable bone and should be completely covered with the denture base. This region, together with the buccal shelf regions on both sides, forms a tripod of good bony support in an otherwise poor mandible, and a suc cessful lower denture can be constructed if these three regions are adequately cov ered.
SM OOTH-SURFACED LO W ER IM PR ESSIO N Behrman8 claims that at least one den ture in a complete upper and lower den ture is a shifting denture in function. He states that this is generally the lower denture and that, in function, it is dis placed and slides back into place by ac tion of the patient’s muscular control.
K e lly : D E N TU R E S F O R M U T IL A T E D J A W S • 1421
this same objective. The m utilated jaw needs a smooth, nondetailed surface in the lower denture more than does the jaw with a high nonresorbed ridge. In the latter instance, there is still much attached gingiva left over the base bone. CONTOURING TO E N H A N CE RETENTION
Fig. I • Diagram illustrates how proper contour ing o f denture base allows muscles of tongue and cheek to aid in holding denture in place
On this basis, he proposes that the impression surface of the lower denture be made smooth and polished. In the edentulous mouth, most of the denturebearing region of the m andible is covered with a loosely attached, freely movable mucosa. This is not true of the edentu lous m axilla. The fine tissue detail in the upper ridge can be copied in the denture base w ith good results but, because of the loosely attached, movable tissue over the average lower ridge, it is not wise to copy the tissue detail with the lower im pression. Better results are obtained in the lower impression if a m aterial is used that flattens and smooths the tissue detail and results in an even smooth surface in the finished denture. W hether this beneficial effect is be cause of the difference in the tissue, or because of the sliding during function that Behrman describes, is not known. Probably, both contribute to the better success achieved with a firm impression m aterial. Impression w ax is ideal for ob taining a smooth surface in the impres sion and in accomplishing a smoothing of the tissue w ithout undue pressure. M any manufacturers have made a more heavy-bodied zinc oxide paste to use for correction in the lower impression w ith
Fish9 first called attention to the impor tant role that the nontissue surfaces, or the polished surfaces of the dentures, play in retention. More recently, Tench10 and Pound11 have emphasized the impor tance of the contouring of these surfaces. Tench and others actually molded the surface by tongue and cheek action and retained the contours in the finished denture.10 Fish advocated that the den tures taper toward the occlusal surfaces and used narrow teeth to obtain a den ture that was triangular in cross section, the apex being at the occlusal surface and the base of the triangle at the tissue surface. T he muscles acting against the sides of the triangle force the denture into place instead of unseating it (Fig. 1). This is a sound principle and is gen erally followed in all contouring. In the lower denture, proper place ment of the lower anterior teeth and contouring of the lower anterior flange will perm it the orbicularis oris and tri angularis muscles in this region to keep the denture seated and stable. In the mo lar region, a lower denture should be rather heavily contoured to prevent food accum ulation. Posterior to the last tooth, however, where the base is in contact w ith the attachm ent of the masseter mus cle, the flange should be rather thin to be tucked under the bulge that this muscle makes there. In the bicuspid re gion on both the upper and lower den tures, the contoured surfaces should have little bulk and taper toward the basal seat to allow the m uscular knots just posterior to the corners of the mouth to act in keeping the dentures seated. We have accepted Fish’s ideas in contouring these surfaces for m any years, visualizing
problem that the oral surgeon can cor rect by creating a flat ridge that can bear a denture base. Flabby tissue over the denture-bearing area is another problem that the oral surgeon can often help solve. Unless there are inflammatory changes and folding in the flabby tissue, however, it is w ell to avoid surgical mod ification and to adjust the impression technic to register this tissue in an undis turbed position. There is much in the literature on sulcus-deepening surgery, but when such surgery is needed most, as in the instance of the pencil-thin mandible, there is no bone to extend against. In the instance of a bone graft, there is enough bone but no sulcus, and an intraoral skin graft as described by Weiss12 gives a ridge equal to a normal ridge.
PRO BLEM OF TH E PERFORATED PALATE
Fig. 2 • A : Large perforation through palate. B: Treatment provides vent by processing large stainless steel needle in acrylic base. Needle is cut off and finished flush with both surfaces after processing
muscle contraction forcing the dentures to place in a static sense. W ith the newer knowledge, gained through cinefluoroscopy of the movements of the denture bases during function, such contouring is even more logical. We can visualize the contours of the denture as surfaces by which the muscles can actually seize the denture and m anipulate it into place after dislodgment.
SU R G ICAL H E LP
M any edentulous mouths present insur mountable problems in denture retention and function, and denture construction should be delayed until the oral surgeon has modified the conditions. The knifeedged lower ridge, for example, is a
A unique problem in complete denture service is th at of a patient w ith a per forated palate. This condition occurs af ter cancer surgery or irradiation, from extensive traum a, or after incomplete repair of a congenital cleft. The use of a vent in the form of a 19-gauge hypo dermic needle shaft offers a simple solu tion to the problem.13 The portion of the shaft of the stainless steel needle is fin ished flush w ith the denture base on both sides. It equalizes pressure between the oral and nasal cavities, but it is small enough so that food or fluids do not get into the nasal cavity from the mouth (Fig. 2 ,3 ). It is easily kept open and clean w ith the wires that come w ith the needles. T he peripheral seal of the den ture base and a seal around the perfora tion m aintain the retention expected in a complete upper denture. The denture retains its so-called “suction” and w ill not dislodge when the patient swallows, smokes, talks, coughs or otherwise sets up differences in air pressure in the nasal and oral cavities.
Fig. 3 • Completed denture shows how needle shaft vent is finished on palatal and nasal surfaces
CLEFT PALATE
T he edentulous congenital cleft palate patient whose cleft is continued through the soft palate presents another problem. In this instance, the oral and nasal cavi ties are never completely shut off, even w ith an obturator, so that the difference in air pressure between the nose and mouth is not a problem in retention. Pe ripheral seal on a complete denture is not possible, so good surface adaptation is relied on for some adhesion of the base to the tissue and, since the advent of the soft silicone rubber liners, the undercuts of the cleft can be engaged for added retention. Dow Comings’ m edical sili cones, Silastic 372 or Silastic 390, can be used for this purpose. H O L L O W DENTURE TO EN H AN C E RETENTION
Often in the m axillary arch where much tissue has been lost and must be restored as p art of the appliance, the mere w eight of the denture m ilitates against good re tention. This problem can be offset by m aking bulky upper appliances hollow. This is simply done by processing the denture as a hollow shell and, after proc essing, sealing the hole by cementing a lid in place w ith one of the self-activating acrylic resins. This gives a light appli ance, and bulky appliances w ill not tend to fall merely because of their own w eight (Fig. 4 ). DENTURES AND IRRADIATED T IS S U E
In these days of cancer consciousness, more patients are encountered who have received, or who w ill receive, heavy ir radiation of the oral structures. It is common practice for the surgeons to ren der these patients edentulous before ra diation to prevent osteoradionecrosis that
sometimes follows tooth extraction after irradiation. Prosthodontists can often save some teeth in these patients and so prevent denture retention problems by constructing lead shields for teeth and supporting bone not in the imm ediate area that the radiologist is treating. Shields often can be m ade for the oppos ing jaw or unilaterally for the same jaw that is to be treated (Fig. 5 ). These shields are made by adapting two thick nesses of baseplate w ax over a cast of the mouth on which the undercuts have been generously filled in and casting this in lead, lining the lead w ith self-activat ing methyl m ethacrylate to get some semblance of fit and then retaining it during treatm ent w ith an adhesive. Patients with irradiated oral tissue pre sent difficult problems. Because of the danger of denture irritation causing os
Fig. 4 • A bulky obturator section on partial denture made hollow so that weight of appliance will not cause loss o f retention
a number of preparations proposed as artificial saliva are somewhat effective. Dykes and others have suggested a for m ula and it, or one sim ilar, serves fairly w ell: gelatin, 20.00 per cent; glycerine, 40.00; sucrose, 5.00; lemon essence, 0.60; sodium benzoate, 0.20; citric acid, 2.00, and am aranth solution, 1.00 per cent, w ith w ater added to make 100.00 per cent. The mass is poured in dry starch molds and the pastilles dried for 12 hours in w arm air. One of these pastilles dis solved in the mouth every three hours leaves a film of mucus-like m aterial, stim ulates any rem aining secreting cells and ensures a reasonably comfortable mouth. SU M M A R Y
teoradionecrosis, it is advisable not to construct dentures for these patients for at least 18 to 24 months after irrad ia tion.14 Cook15 reported necrosis in 11 pa tients. Necrosis occurred in 4 of the patients after tooth extraction and in 3 after denture irritation. One of the 3 cases of necrosis after denture irritation oc curred 13 years after the patient’s last exposure to radium . A soft liner of sili cone rubber should be used in dentures for irradiated patients to minimize the danger of denture irritation. After irradiation, a great problem in denture retention is lack of saliva. This condition occurs occasionally from sys temic causes other than destruction of the glandular tissue by radiation, espe cially in the elderly. There is no easy or good solution to this problem, although
Several means to obtain better denture retention, especially in the patient with m utilated tissue, have been reviewed. T he structures under and adjacent to the denture bases in the posterior part of the mouth have been enum erated, and their relationship to denture outline has been stressed. Most dentures, both m axil lary and m andibular, lack sufficient cov erage in the posterior part of the mouth. Even the best fitting dentures move much more in function than has been
Fig. 5 • Lead radiation shield on cast. Shield allows teeth to be saved fo r retaining appliance
K e lly : D E N TU R E S FO R M U T IL A T E D J A W S • 1425
acknowledged previously, and partial so lution of the problem is giving closer attention to the contouring of the pol ished surfaces and using a smooth tissue surface on the lower denture. Surgical correction of some conditions to improve denture tolerance is advo-
cated. Special problems and possible so lutions are suggested for perforated pal ate and congenital clefts. Making bulky maxillary dentures hollow to enhance re tention is advocated. The problems be fore and after heavy irradiation of the oral tissues are discussed.
Presented at the one hundred and fifth annual session, American Dental Association, San Francisco, Nov. 9-12, 1964. *Associate professor of denture prosthesis, University of C alifornia School o f Dentistry, San Francisco, 94122. 1. Sheppard, I. M. Denture base dislodgm ent during mastication. J. Pros. Den. 13:462 May-June 1963. 2. Brill, N., Tryde, G., and Schübeler, S. Role of exteroceptors in denture retention. J. Pros. Den. 9:761 Sept.-Oct. 1959. 3. Skinner, E. W ., C am pbell, R. L., and Chung, P. C linical study o f the forces required to dislodge maxil lary denture bases of various designs. JAD A 47:671 Dec. 1953.
based upon the anatomy of the mouth. JADA 31:1174 Sept. 1944. 8. Behrman, S. J. Magnets im planted in the mandible: aid to denture retention. JADA 68:206 Feb. 1964. 9. Fish, E. W . Lower fu ll denture construction (im po r tance of anatomical m odelling o f the polished surface). D. Survey 12:389 O ct. 1936. 10. Nelson, A . A . The use o f neuro-muscular function in denture construction based upon the ong'ma\ concept of Russell W ilfo rd Tench. In Syllabus of the Detroit Dental C linic Club, Detroit, I960. 11. Pound, E. A pplying harmony in selecting and arranging teeth. D. C iin. N. A m erica March 1962, p. 241-258. 12. Weiss, L. R. Intra-oral skin g ra ft as an aid to denture construction. JAD A 34:389 March 15, 1947. 13. Kelly, E. K. Retentive complete dentures fo r pa tients with perforated palates. J. Pros. Den. 12:425 May-June 1962. (4. Castigliano, S. G. In Burket, L. W . O ral medicine: diagnosis and treatment, ed. 3. Philadelphia, J. B. Lippincott Co., 1957, p. 455-504. 15. Cook, T. J. Late radiation necrosis of the ¡aw bones. J. O ral Surg. 10:118 A p ril 1952.
4. Stanitz, J. D. Analysis o f the part played by the fluid film in denture retention. JAD A 37:168 Aug. 1948. 5. Snyder, F. C., and others. Effect of reduced atmos pheric pressure upon retention of dentures. JAD A 32:445 A p ril 1945. 6. Boucher, C. O . Impressions fo r complete dentures. JADA 30:14 Jan. 1943. 7. Boucher,
C.
O.
Com plete
denture
impressions
Dental Accidents Am ong School Children • Dental accidents not associated with athletic activities are more than twice as common among school children as dental accidents involving athletics, according to a survey by the Washington Dental Service. T he survey revealed that 71 per cent of dental accidents to children covered by the program were not associated with athletics, while 29 per cent of the accidents were connected with athletic activities. The average cost of athletic accidents, however, exceeded that of nonathletic accidents, $67 to $58. Approximately 80 per cent of dental accident costs and 72 per cent of dental accident cases involved teeth broken, chipped, fractured or knocked out. The majority of accidents involved boys, with less than 15 per cent involving girls. The cost per dental accident for all children averaged $61 during the seven-year period covered by the study, increasing from $51 in 1957 to $71 in 1964. During this period, however, the coverage of the program was extended from accidents occurring only during school hours or in connection with school activities to accidents occurring at any place or time. The rate of dental accidents averaged 1.24 accidents per 100 enrolled children for the entire period covered by the survey. Approximately half the accidents each year occurred between September and December, and almost three fourths occurred between September and February, due to the added impact of athletic activities such as football and basketball that involve more dental accidents than athletic activities carried on during the spring and summer months. Washington Dental Service, Seattle.
In co n stru ctin g c o m p le te den tu res fo r p a t ie n ts w ith m u ti la te d ja w s, t h e m a in basis f o r s u c c e s s is th a t t h e p r o c e d u r e s g o v e r n i n g r e te n ti o n o f d e n t u r e s in a n y p a t ie n t b e f o l l o w e d ca r e fu lly . S p e cifica lly , b o th m axillary a n d m a n d ib u la r d e n t u r e s u su ally lack s u ffic ie n t c o v e r a g e in t h e p o s t erio r p a rt o f t h e m o u t h , a n d m o r e a t t e n tion s h o u l d b e g i v e n to t h e c o n t o u r i n g o f p o l i s h e d su rfa ce s. S u r g ic a l c o r r e c t i o n a n d s p e c i a l d e n tu r es , s u c h as h o l l o w m axillary d e n tu r e s , i m p r o v e d e n t u r e t o l e r a n c e in s o m e instances.
1 ’he term mutilated jaw includes exten sive loss of bony support. The loss of normal denture base support may result from extreme resorption of the alveolar process, from surgical removal of the supporting tissue to eradicate a malig nancy, from extensive traumatic loss or from a congenital lack of tissue as in the cleft palate. The term maxillofacial also is used to describe these losses. Patients with mutilated jaws have a problem in denture retention that sometimes can be met with special procedures. Especially, however, the problem requires faithful
adherence to those basic technical proce dures governing retention and stability that all patients obtaining complete den tures should, but frequently do not, re ceive. Retention and stability are two terms applied to express one quality—the ability of the dentures to remain in place against the basal seat. Recent research and thinking on this topic emphasize function rather than a static situation. The denture movements during mastica tion have been studied by Sheppard1 and others, using cinefluoroscopy. They found that even the best-fitting dentures move considerably during function and are made tolerable only by the patient’s mus cular control in reseating them. Brill2 has recently called attention to the role of neuromuscular control by the patient in retaining the dentures during function. These observations do not lessen the im portance of good fit in dentures; rather, they add further requirements of denture technic. The polished surfaces of the den ture must be contoured to facilitate the control of the dentures by the tongue and cheek muscles. The impression surface of the lower denture must be smooth to allow it to move in function without ir ritating the mucosa.
1420 • J . A M E R . D E N T . A S S N .: V o l. 71, D e c. 1765
DENTURE BASE FORM AND EXTENSION It is generally agreed that maximum sta bility in complete dentures is obtained with close adaptation of the base to the tissues, coverage of as large an area as permitted by the anatomic form of the mouth and a firm peripheral seal.3’6 Re gardless of the technic or materials used; knowledge of the anatomy of the area is most important. In the maxillary den ture, the most common fault is an over or under extension at the posterior bor der. The posterior border includes not only that region commonly called the postdam region where the hard palate meets the soft palate, it includes the lat eral region where the denture border ex tends through the hamular notch and curves up behind and lateral to the tu berosity to gain the height of the denture flange. This region, extending from the hamular notch to the height of the flange, is extremely important from the stand point of denture seal. It should be termed the internal pterygoid region because it is limited by a slip of the internal pterygoid muscle that originates on the distal and lateral aspect of the tuberosity, far exter nal to the principal origin of the muscle. When properly extended in this region, the denture border assumes a characteris tic double curvature on the medial edge of a flattened, rather wide border. In the hamular notch area, the den ture is often underextended because the notch is often quite a few millimeters distal to the termination of the tuberosity. The notch should be palpated to deter mine the extent of the denture in this region. The posterior border should terminate at the vibrating line. It is difficult to understand why so many dentures are underextended in this region when the demarcating, movable tissue is so easily demonstrated. It can only be assumed that the extent of the denture is often determined on a cast in the laboratory without reference to the patient’s mouth. The most common error in the com
plete lower denture is a failure to extend the denture base distally, both distobuccally and distolingually, as well as over the retromolar pad. The denture base must completely cover the pad, extending lingually into the depression that lies lin gual and inferior to the pad and as far distal in this area as the palatoglossus muscle permits. On the buccal aspect, the distal border conforms to the attachment of the masseter and extends buccally to the termination of the masseter muscle. This region, which Boucher7 calls the buccal shelf area, furnishes excellent sup port, and the lower denture should be widest at this point. The shape, formed by muscle attachments to the mandible, is characteristic regardless of the amount of alveolar ridge resorption that has taken place. A second region where many lower dentures are deficient is the an terior lingual region. Here, the thickness of the denture border will help attain a seal when the depth of flange is limited. The flange in this region should be as wide as the location of the openings of the sublingual glands in the plica sub lingualis permit. When there is almost complete resorption of the alveolar proc ess, the genial tubercle appears as a rounded bony prominence in this region. This is a dense, unchangeable bone and should be completely covered with the denture base. This region, together with the buccal shelf regions on both sides, forms a tripod of good bony support in an otherwise poor mandible, and a suc cessful lower denture can be constructed if these three regions are adequately cov ered.
SM OOTH-SURFACED LO W ER IM PR ESSIO N Behrman8 claims that at least one den ture in a complete upper and lower den ture is a shifting denture in function. He states that this is generally the lower denture and that, in function, it is dis placed and slides back into place by ac tion of the patient’s muscular control.
K e lly : D E N TU R E S F O R M U T IL A T E D J A W S • 1421
this same objective. The m utilated jaw needs a smooth, nondetailed surface in the lower denture more than does the jaw with a high nonresorbed ridge. In the latter instance, there is still much attached gingiva left over the base bone. CONTOURING TO E N H A N CE RETENTION
Fig. I • Diagram illustrates how proper contour ing o f denture base allows muscles of tongue and cheek to aid in holding denture in place
On this basis, he proposes that the impression surface of the lower denture be made smooth and polished. In the edentulous mouth, most of the denturebearing region of the m andible is covered with a loosely attached, freely movable mucosa. This is not true of the edentu lous m axilla. The fine tissue detail in the upper ridge can be copied in the denture base w ith good results but, because of the loosely attached, movable tissue over the average lower ridge, it is not wise to copy the tissue detail with the lower im pression. Better results are obtained in the lower impression if a m aterial is used that flattens and smooths the tissue detail and results in an even smooth surface in the finished denture. W hether this beneficial effect is be cause of the difference in the tissue, or because of the sliding during function that Behrman describes, is not known. Probably, both contribute to the better success achieved with a firm impression m aterial. Impression w ax is ideal for ob taining a smooth surface in the impres sion and in accomplishing a smoothing of the tissue w ithout undue pressure. M any manufacturers have made a more heavy-bodied zinc oxide paste to use for correction in the lower impression w ith
Fish9 first called attention to the impor tant role that the nontissue surfaces, or the polished surfaces of the dentures, play in retention. More recently, Tench10 and Pound11 have emphasized the impor tance of the contouring of these surfaces. Tench and others actually molded the surface by tongue and cheek action and retained the contours in the finished denture.10 Fish advocated that the den tures taper toward the occlusal surfaces and used narrow teeth to obtain a den ture that was triangular in cross section, the apex being at the occlusal surface and the base of the triangle at the tissue surface. T he muscles acting against the sides of the triangle force the denture into place instead of unseating it (Fig. 1). This is a sound principle and is gen erally followed in all contouring. In the lower denture, proper place ment of the lower anterior teeth and contouring of the lower anterior flange will perm it the orbicularis oris and tri angularis muscles in this region to keep the denture seated and stable. In the mo lar region, a lower denture should be rather heavily contoured to prevent food accum ulation. Posterior to the last tooth, however, where the base is in contact w ith the attachm ent of the masseter mus cle, the flange should be rather thin to be tucked under the bulge that this muscle makes there. In the bicuspid re gion on both the upper and lower den tures, the contoured surfaces should have little bulk and taper toward the basal seat to allow the m uscular knots just posterior to the corners of the mouth to act in keeping the dentures seated. We have accepted Fish’s ideas in contouring these surfaces for m any years, visualizing
problem that the oral surgeon can cor rect by creating a flat ridge that can bear a denture base. Flabby tissue over the denture-bearing area is another problem that the oral surgeon can often help solve. Unless there are inflammatory changes and folding in the flabby tissue, however, it is w ell to avoid surgical mod ification and to adjust the impression technic to register this tissue in an undis turbed position. There is much in the literature on sulcus-deepening surgery, but when such surgery is needed most, as in the instance of the pencil-thin mandible, there is no bone to extend against. In the instance of a bone graft, there is enough bone but no sulcus, and an intraoral skin graft as described by Weiss12 gives a ridge equal to a normal ridge.
PRO BLEM OF TH E PERFORATED PALATE
Fig. 2 • A : Large perforation through palate. B: Treatment provides vent by processing large stainless steel needle in acrylic base. Needle is cut off and finished flush with both surfaces after processing
muscle contraction forcing the dentures to place in a static sense. W ith the newer knowledge, gained through cinefluoroscopy of the movements of the denture bases during function, such contouring is even more logical. We can visualize the contours of the denture as surfaces by which the muscles can actually seize the denture and m anipulate it into place after dislodgment.
SU R G ICAL H E LP
M any edentulous mouths present insur mountable problems in denture retention and function, and denture construction should be delayed until the oral surgeon has modified the conditions. The knifeedged lower ridge, for example, is a
A unique problem in complete denture service is th at of a patient w ith a per forated palate. This condition occurs af ter cancer surgery or irradiation, from extensive traum a, or after incomplete repair of a congenital cleft. The use of a vent in the form of a 19-gauge hypo dermic needle shaft offers a simple solu tion to the problem.13 The portion of the shaft of the stainless steel needle is fin ished flush w ith the denture base on both sides. It equalizes pressure between the oral and nasal cavities, but it is small enough so that food or fluids do not get into the nasal cavity from the mouth (Fig. 2 ,3 ). It is easily kept open and clean w ith the wires that come w ith the needles. T he peripheral seal of the den ture base and a seal around the perfora tion m aintain the retention expected in a complete upper denture. The denture retains its so-called “suction” and w ill not dislodge when the patient swallows, smokes, talks, coughs or otherwise sets up differences in air pressure in the nasal and oral cavities.
Fig. 3 • Completed denture shows how needle shaft vent is finished on palatal and nasal surfaces
CLEFT PALATE
T he edentulous congenital cleft palate patient whose cleft is continued through the soft palate presents another problem. In this instance, the oral and nasal cavi ties are never completely shut off, even w ith an obturator, so that the difference in air pressure between the nose and mouth is not a problem in retention. Pe ripheral seal on a complete denture is not possible, so good surface adaptation is relied on for some adhesion of the base to the tissue and, since the advent of the soft silicone rubber liners, the undercuts of the cleft can be engaged for added retention. Dow Comings’ m edical sili cones, Silastic 372 or Silastic 390, can be used for this purpose. H O L L O W DENTURE TO EN H AN C E RETENTION
Often in the m axillary arch where much tissue has been lost and must be restored as p art of the appliance, the mere w eight of the denture m ilitates against good re tention. This problem can be offset by m aking bulky upper appliances hollow. This is simply done by processing the denture as a hollow shell and, after proc essing, sealing the hole by cementing a lid in place w ith one of the self-activating acrylic resins. This gives a light appli ance, and bulky appliances w ill not tend to fall merely because of their own w eight (Fig. 4 ). DENTURES AND IRRADIATED T IS S U E
In these days of cancer consciousness, more patients are encountered who have received, or who w ill receive, heavy ir radiation of the oral structures. It is common practice for the surgeons to ren der these patients edentulous before ra diation to prevent osteoradionecrosis that
sometimes follows tooth extraction after irradiation. Prosthodontists can often save some teeth in these patients and so prevent denture retention problems by constructing lead shields for teeth and supporting bone not in the imm ediate area that the radiologist is treating. Shields often can be m ade for the oppos ing jaw or unilaterally for the same jaw that is to be treated (Fig. 5 ). These shields are made by adapting two thick nesses of baseplate w ax over a cast of the mouth on which the undercuts have been generously filled in and casting this in lead, lining the lead w ith self-activat ing methyl m ethacrylate to get some semblance of fit and then retaining it during treatm ent w ith an adhesive. Patients with irradiated oral tissue pre sent difficult problems. Because of the danger of denture irritation causing os
Fig. 4 • A bulky obturator section on partial denture made hollow so that weight of appliance will not cause loss o f retention
a number of preparations proposed as artificial saliva are somewhat effective. Dykes and others have suggested a for m ula and it, or one sim ilar, serves fairly w ell: gelatin, 20.00 per cent; glycerine, 40.00; sucrose, 5.00; lemon essence, 0.60; sodium benzoate, 0.20; citric acid, 2.00, and am aranth solution, 1.00 per cent, w ith w ater added to make 100.00 per cent. The mass is poured in dry starch molds and the pastilles dried for 12 hours in w arm air. One of these pastilles dis solved in the mouth every three hours leaves a film of mucus-like m aterial, stim ulates any rem aining secreting cells and ensures a reasonably comfortable mouth. SU M M A R Y
teoradionecrosis, it is advisable not to construct dentures for these patients for at least 18 to 24 months after irrad ia tion.14 Cook15 reported necrosis in 11 pa tients. Necrosis occurred in 4 of the patients after tooth extraction and in 3 after denture irritation. One of the 3 cases of necrosis after denture irritation oc curred 13 years after the patient’s last exposure to radium . A soft liner of sili cone rubber should be used in dentures for irradiated patients to minimize the danger of denture irritation. After irradiation, a great problem in denture retention is lack of saliva. This condition occurs occasionally from sys temic causes other than destruction of the glandular tissue by radiation, espe cially in the elderly. There is no easy or good solution to this problem, although
Several means to obtain better denture retention, especially in the patient with m utilated tissue, have been reviewed. T he structures under and adjacent to the denture bases in the posterior part of the mouth have been enum erated, and their relationship to denture outline has been stressed. Most dentures, both m axil lary and m andibular, lack sufficient cov erage in the posterior part of the mouth. Even the best fitting dentures move much more in function than has been
Fig. 5 • Lead radiation shield on cast. Shield allows teeth to be saved fo r retaining appliance
K e lly : D E N TU R E S FO R M U T IL A T E D J A W S • 1425
acknowledged previously, and partial so lution of the problem is giving closer attention to the contouring of the pol ished surfaces and using a smooth tissue surface on the lower denture. Surgical correction of some conditions to improve denture tolerance is advo-
cated. Special problems and possible so lutions are suggested for perforated pal ate and congenital clefts. Making bulky maxillary dentures hollow to enhance re tention is advocated. The problems be fore and after heavy irradiation of the oral tissues are discussed.
Presented at the one hundred and fifth annual session, American Dental Association, San Francisco, Nov. 9-12, 1964. *Associate professor of denture prosthesis, University of C alifornia School o f Dentistry, San Francisco, 94122. 1. Sheppard, I. M. Denture base dislodgm ent during mastication. J. Pros. Den. 13:462 May-June 1963. 2. Brill, N., Tryde, G., and Schübeler, S. Role of exteroceptors in denture retention. J. Pros. Den. 9:761 Sept.-Oct. 1959. 3. Skinner, E. W ., C am pbell, R. L., and Chung, P. C linical study o f the forces required to dislodge maxil lary denture bases of various designs. JAD A 47:671 Dec. 1953.
based upon the anatomy of the mouth. JADA 31:1174 Sept. 1944. 8. Behrman, S. J. Magnets im planted in the mandible: aid to denture retention. JADA 68:206 Feb. 1964. 9. Fish, E. W . Lower fu ll denture construction (im po r tance of anatomical m odelling o f the polished surface). D. Survey 12:389 O ct. 1936. 10. Nelson, A . A . The use o f neuro-muscular function in denture construction based upon the ong'ma\ concept of Russell W ilfo rd Tench. In Syllabus of the Detroit Dental C linic Club, Detroit, I960. 11. Pound, E. A pplying harmony in selecting and arranging teeth. D. C iin. N. A m erica March 1962, p. 241-258. 12. Weiss, L. R. Intra-oral skin g ra ft as an aid to denture construction. JAD A 34:389 March 15, 1947. 13. Kelly, E. K. Retentive complete dentures fo r pa tients with perforated palates. J. Pros. Den. 12:425 May-June 1962. (4. Castigliano, S. G. In Burket, L. W . O ral medicine: diagnosis and treatment, ed. 3. Philadelphia, J. B. Lippincott Co., 1957, p. 455-504. 15. Cook, T. J. Late radiation necrosis of the ¡aw bones. J. O ral Surg. 10:118 A p ril 1952.
4. Stanitz, J. D. Analysis o f the part played by the fluid film in denture retention. JAD A 37:168 Aug. 1948. 5. Snyder, F. C., and others. Effect of reduced atmos pheric pressure upon retention of dentures. JAD A 32:445 A p ril 1945. 6. Boucher, C. O . Impressions fo r complete dentures. JADA 30:14 Jan. 1943. 7. Boucher,
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Dental Accidents Am ong School Children • Dental accidents not associated with athletic activities are more than twice as common among school children as dental accidents involving athletics, according to a survey by the Washington Dental Service. T he survey revealed that 71 per cent of dental accidents to children covered by the program were not associated with athletics, while 29 per cent of the accidents were connected with athletic activities. The average cost of athletic accidents, however, exceeded that of nonathletic accidents, $67 to $58. Approximately 80 per cent of dental accident costs and 72 per cent of dental accident cases involved teeth broken, chipped, fractured or knocked out. The majority of accidents involved boys, with less than 15 per cent involving girls. The cost per dental accident for all children averaged $61 during the seven-year period covered by the study, increasing from $51 in 1957 to $71 in 1964. During this period, however, the coverage of the program was extended from accidents occurring only during school hours or in connection with school activities to accidents occurring at any place or time. The rate of dental accidents averaged 1.24 accidents per 100 enrolled children for the entire period covered by the survey. Approximately half the accidents each year occurred between September and December, and almost three fourths occurred between September and February, due to the added impact of athletic activities such as football and basketball that involve more dental accidents than athletic activities carried on during the spring and summer months. Washington Dental Service, Seattle.