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The role of the prosthodontist in preprosthetic surgery
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The .role of the prosthoaontist In preprosthetic surgery, Noel O. Wilkie,.D,D.S.* Naval Graduate Dental Sctzoot, NationaI Navat Medical Center, Bethesdai Md.
Pesent-day
dental literature, especially that of oral surgery and prosthetic dentistry, is repeatedly emphasizing the problem of idiopathic changes in the supporting tissues for complete dentures. These numerous reports and studies stress the nearly epidemic pi~oportions of the problem as they search for unknown etiologic factors, describe the nature of the problem in detail, and propose many different means of treatment. The bone of the residual ridge seems to be the focus of the problem. Although great strides have been made toward preservation of this bone, in the future, the edentulous maxillae or mandible that is unable to support complete dentures or at best support dentures only with great difficulty will receive more attention. In addition, more readily available hetalth-care benefits and epidemiologic studies will show alveolar bone loss to be a major health problem now and in the future. :One solution to this problem is surgical intervention in conjunction with prosthetic rehabilitation. As this solution is presented, three contributions arising from it will be discussed at length. They are: (1) denture stability is influenced by soft tissuesas well as bone, and conclusions are made concerning conditions of the soft tissues which are most favorable to stability; (2) diagnostic criteria are outlined which lead to more critical evaluation of the denture-supporting soft tissues; and (3) recently developed preprosthetic surgical procedures with emphasis on autogenous r i b grafts are introduced into the literature of prosthodontics.
HISTORY OF THE PROBLEM Studies of the alveolar bone, the residual edentulous ridge, and the supporting mucosal tissues have revealed the following facts. (1) The alveblar bone in individuals with natural teeth is labile in nature. The
The opinions or assertions contained herein are those of the author and are not to be construed as-official or a s--Feflecting the views of the Navy Department or the naval service at large. Read before the Academy•of Denture Prosthetics, San Francisco, Calif. **Captain (DC) USN; formerly, Chief, Complete Denture Division, Prosthodontics Department.
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response of this bone to stimuli, normal or abnormal, varies from individual to individual, and this response is not predictable. This premise is important, because it gives us a clue to the nature of our problem before the individual becomes edentulous. (2) The response of the alveolar bone to tooth loss and subsequent function under dentures varies from individual to individual, but it can be predicted that the response will be some degree of reduction of the bone of the residual ridges. (3) Many observers have attempted without success to correlate changes in the residual ridges to age, sex, systemic and endocrine disturbances, pre-extraction periodontal status, occlusion in dentures, denture base materials, immunologic response, habit patterns, lack of periodic denture maintenance or reconstruction, and other biologic and iatrogenic factors. Few, if any, studies have attempted to correlate these same factors with pathognomonic changes in the supporting and overlying mucosal tissues. The causes Of these problems must be discovered in order to arrive at valid preventive approaches in treatment. (4) It can be predicted that the amount of reduction will be greater in the mandibular ridge than in the maxillary ridge. Tallgren, 1 in a longitudinal study, found the loss in the mandibular ridge to be four times greater. This tells us where we will see the majority of our problems. Coincidentally, it is the mandibular ridge that has the least amount of support for dentures in the first place. (5) Tallgren 1 also observed a greater loss of bone tissue in the anterior ridge region than in the posterior region. This complicates treatment by prosthetic means alone, because we are forced to use inclined planes for our supporting bases. (6) It can be predicted that the rate of bone loss will be most rapid during the first year. ~ This rate of bone loss seems to be less (there is a smaller amount of ridge reduction) if the ridges are placed in function directly following extraction. Johnson 2 and Wictorin a reported such results with immediate maxillary dentures. It appears that immediate functioning of all areas, such as occurs under transitional dentures, likewise encourages the preservation of the maximum amounts of bone. Longitudinal studies reporting the effects of function under transitional dentures have not been reported; however, personal observations and those of Payne 4 and of Rayson and Wesley 5 seem to verify slowing in the rate of bone loss. (7) The response in the mucosaI tissues varies as well. The response can be slight displacement of the mucosa within physiologic limits. This condition is reversible by rest. A more severe response will be infiltration of inflammatory cells into the subepithelial connective tissues. This condition may be reversed by removal of the dentures or by alternating periods of removal with periods of wearing the denture with tissue-conditioning materials. Fibrous connective-tissue proliferation with add{tional numbers of inflammatory cells in the submucosa is representative of the most severe response of the mucosal supporting tissues. This is almost always an irreversible condition, and surgical intervention may have to be recommended. It can be suspected that an extensive change in the mucosal and submucosal tissues may be either the predecessor to or occur in conjunction with the most severe fonals of bone loss. HISTORY OF SOLUTIONS TO THE PROBLEM
The treatment of these tissue problems has generally fallen into three philosophies: No tissue alteration. The existing tissue form and structure are recognized but are
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not altered in any manner, and the prosthetic treatment is adapted to suit this set of conditions. Such prosthetic treatment includes specialized impression techniques, changes in occlusal patterns, specialized tooth forms, metallic denture base materials, and other nonroutine techniques. Nonsurgicat and surgical management of soft tissues. The soft tissues may be assessed as having reversible conditions. In this:situation, initiation of prosthetic treatment will include instructions for periodic ~,emoval of existing dentures, correction of the occlusion in the existing dentures, and use of tissue-conditioning materials, as advocated by Lytle2 If tissue examinati6"n reveals nonreversible tissue conditions, surgery may be recommended. In past years, the emphasis of this preprosthetic surgery has been on vestibular alteration, with specia ! attention given to a quantitative deepening rather than a qualitative change in the nature of the soft tissues. The most frequently cited surgical procedure for changing the nature of the tissues is the use of grafted autogenous skin. ~ The most common site for this procedure is the mandibular buccolabial region, and frequently the extent of the graft rises to the inner surface of the lower lip. In the process of refining gingival surgery, periodontists have stimulated interest in surgical techniques which increase amounts of attached mucosa. Now the literature of oral surgery is beginning to report mucosal transplants, use of freeze-dried homografts of skin, and secondary epithelialization procedures which have the objective of changing the nature as well as the extent of prosthesis-bearing tissues. Surgical management of the supporting bone. In some individuals, changes in the supporting hard and soft tissues are so severe as to require alterations in or on the residual bone. Mechanical fixation of various electropassive metals, mainly chromiumcobalt-nickel and titanium alloys and tantalum, on or into the residual bone has been frequently reported. For approximately 25 years, the subperiosteal metallic implant has been with us. A critical review of the research, available information, and clinical results of this type of implant was reported by the University of Buffalo at the direction of the Council on Dental Materials and Devices of the American Dental Association. s This report is not encouraging and points out the need for a continuing research effort with this type of implant. Endosteal metallic implants of the pin, screw, staple, and blade varieties are currently being popularized. Development of better techniques for study, adequately controlled longitudinal studies, and careful peer review of the trairiing for use and clinical application are imperative if endosteal implants are to be accepted as a future solution to our problem. Subperiosteal implants of alloplastic materials have recently been introduced2 The most common of thesehave been vitreous carbon and ceramic materials. Although ongoing animal research is being conducted, no conclusive evidence can be found a s a basis for introducing these materials into everyday use in human subjects at this time. Augmentation of the residual ridge with bone has been a sought-after approach, because biocompatability of the graft and the host site is virtually assured. Cryopreserved (freeze-dried) cartilage and bone were used successfully as allografts in artificially created intraoral defects in 1953 by Cooksey? ° Boyne and Cooksey~ later used freeze-dried bone and cartilage subperiosteally on the ridge crest both experimentally in dogs and clinically in human patients. Clinical and radiographic evaluation for as long as four and a half years indicated that these grafts became an integral part of the ridge and were capable of supporting complete
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denture prostheses. Richter, Sugg, and Boyne 12 had success in an experiment with autogenous hematopoietic bone marrow held in a chrome-c0balt cage lined with a cellulose acetate Millipore filter. This filter effectively prohibited invasion of connective tissue. These' experiments on the mandibles of dogs resulted in the formation of supracortical cancellous bone. The technique has subsequently been used successfully in man to repair discontinuity defects in bone traumatized from war wounds and accidents. Most recently, Davis and his associates 1" have brought to this country surgica ! techniques introduced by Prof. Hugo Obwegeser of Zurich, Switzerland. This surgica 1 method utilizes autogenous block grafts from the ilium or, more commonly, two ribs placed via a transoral approach in either the mandible or the maxillae. Almost always, a subsequent surgical procedure is a vestibuloplasty with a splitthickness graft of skin. If the procedures have been directed toward improvement of the mandible, a lowering of the entire floor of the mouth is carried out simultaneously with ridge skin grafting, as advocated by Macintosh and Obwegeser. TM Results of these procedures have been encouraging. Postgrafted patients h a v e been wearing prostheses under observation for more than four years. In these patients, it is expected that 40 to 50 per cent of the vertical height of bone gained at surgery will be lost during the first 12 to 18 months. Terry* has followed a great number of these patients postoperatively and observed a lessened resorption rate after this period, with the remaining residual bone appearing to become more dense radiographically. A 10 year longitudinal study is now in progress which will critically evaluate this surgical technique. Attendant prosthetic procedures for these patients are very specific and are described in detail herein. THE INFLUENCE OF SOFT TISSUES ON DENTURE STABILITY
Certain observations have been made during the prosthetic treatment of patients who have undergone preprosthetic surgery. T h e first is that a residual ridge which has had only an autograft of bone and not the skin graft or "mouth-floor-plasty" still has very mobile tissues. Record bases placed on these ridges are not stable, and it is difficult to assess retention. The second observation is that the initial complete denture which is made following bone and skin grafting is very stable. This denture has planned foreshortened borders in its entire periphery, and it contacts only on the grafted skin, not mucosal tissues. It purposely does not extend into the vestibular areas. In spite of this, stability of the denture is greatly improved. Finally, if the patients' needs dictate, necessary preprosthetic procedures may be those which change the nature of the supporting soft tissues only and not bone. The initial dentures in these patients demonstrate marked improvements in stability. Although not so easily observed, retention seems to improve as well. From these observations, one can conclude that contour and amount of bone are not so influential toward denture stability as are the nature and attachment of the soft tissues to that bone. The ideal attachment should be surface epithelium with minimal amounts of connective tissue interposed between it and the periosteum. From the prosthetic standpoint, grafted skin should not line the vestibule or inner lip (Fig. 1 ). Normal oral mucosa, which is resilient and which secretes its normal *B. C. Terry: Preprosthetic Surgery. Unpublished report.
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Fig. 1. Vestibular deepening with skin graft lining the entire vestibule and inner lower lip. Fig. 2. "Mouth-floor-plasty" with a split-thickness autogenous skin graft short of the vestibule. Advantages are normal meniscus formation and lack of scar tissue at denture border.
Fig. 3. Incipient fissure at the junction of attached and unattached mucosa (arrow). Fig. 4. Fissuring within attached mucosa. fluids, serves to form a much better meniscus at the denture border than does skin (Fig. 2). Considering this, precise diagnostic criteria for the soft tissues will be set forth. Equally good criteria have been developed for bone assessment, but this should not be given a disproportionate share of the diagnostic effort. A diagnosis developed from information about these tissues will provide the ideal common meeting ground from which the oral surgeon and the prosthodontist can plan treatment. DIAGNOSTIC CRITERIA USED IN TISSUE EVALUATION Soft-tissue assessment
Amounts of attached mucosa. T h e amount of attached mucosa should be no less than a norm, which covers the crest and one third to one half of the slopes of each ridge. Lesser amounts may be prevalent in some areas but should not be accepted as a general norm. Fissuring. Fissuring is commonly seen at the junction of the attached and unattached mucosa (Fig. 3). It can occur within each mucosal area as well (Figs. 4 and 5). It may be ulcerated (Fig. 5) but generally is not. The fissure is a signal of potential hyperplasia of the tissues and, if severe, can be eliminated by mueosal and skin grafts, freeze-dried skin allografts, or secondary epithelialization procedures. It
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Fig. 5. An ulcerated fissure within unattached mucosa. Fig. 6. Attached mucosa which can be folded over the unattached mucosa.
Fig. 7. A clear plastic template showing folding with function. Fig. 8. Tissues corrected with a submucous resection technique.
should be understood that secondary epithelialization procedures regress up to 50 per cent. This is no problem in the treatment of fissuring, because usually there is adequate mucosa where it is needed. Folding. This usually is the next sequence if the fissuring problem worsens. It indicates hyperplasia of the submucosal connective tissues on one or both sides of the fissure (Fig. 6). It seems to be self-perpetuating, especially with an overlying denture. It can be seen extremely well in function under a clear plastic template placed as a denture base (Fig. 7). If there is adequate underlying bone, the fissure and folds of tissue should be eliminated by the surgical procedure known as submucous resection (Fig. 8), and the surgical technique is well outlined by Macintosh and Obwegeser. 14 This removes redundant connective tissue between the mucosa and periosteum on the lateral side of the ridge and readapts the mucosa directly to the periosteum up to the point of deepest vestibular height. The submucous resection is most commonly used in the maxillary anterior ridge region. Mobility of tissue. An excessive amount of soft tissue is a reflection of severe changes in the supporting bone (Fig. 9). This results in tissue mobility. The tissues may demonstrate scarring, great amounts of connective-tissue proliferation, and decreased amounts of attached mucosa. Bone correction may not be necessary, but
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Fig. 9. Extremely mobile mucosal tissues indicating severe resorption of bone. Fig. 10. The floor of the mouth in repose lies above the ridge crest. extensive soft-tissue procedures, such as excision of the connective tissue followed by secondary epithelialization or mucosal or skin grafts, should be the treatment of choice. Position of the mouth floor. Should the m o u t h floor in repose lie near the level of the ridge crest or above (Fig. l e), a "mouth-floor-plasty" should be recommended. These very mobile tissues, consisting of connective, vascular, muscular, and glandular tissues, will have to be permanently lowered, with the muscles affixed at the lowest possible level on the inner aspects of the mandible. Bone assessment
A pantographic and lateral cephalometric radiographic survey is necessary to assess the bone. Soft-tissue height in relation to the residual bone can be visualized by placing a strip of tinfoil in the existing dentures or in a plastic template which covers the ridges. Maxillary survey. When the residual bone level is seen to be approaching the level of the anterior nasal spine and generalized resorption is so severe that a nearly equal plane exists between the vestibule and the palate (Fig. l 1), the diagnostic team should consider bone grafting. Without bone augmentation, there can be no vestibule and no obstruction to lateral or anterior posterior movement of the denture. It has also been observed that retention of the maxillary denture is minimal owing to the ease with which the palatal seal can be broken. In these patients, even gravity forces are enough to make wearing a denture nearly impossible. Mandibular survey. If the horizontal body of the mandible demonstrates a thickness no greater than 1 to 1.5 cm. when viewed in the radiograph (Fig. 12), bone augmentation procedures should be considered. Without such augmentation, vestibuloplasty and lowering of the mouth floor could gain little depth. A greater danger is that lesser amounts of residual bone are susceptible to pathologic fracture. Interridge distance survey. As a final determinant, the interridge distance should be assessed at the tentative vertical dimension of occlusion. This can be visualized on properly mounted casts and will reveal the mechanical difficulties one must labor under should no augmentation procedures be attempted.
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Prosthodontist's role in preprosthetic surgery 393
Fig. 1I. A radiographic survey of the maxillae. Note that the residual bone height is level with the anterior nasal spine and base (center) of the palate. Fig. 12. A Panorex radiographic survey of a mandible. The measured thickness of the body of the mandible is less than 1.5 cm. THE ROLE OF THE PROSTHODONTIST IN SURGICAL RIDGE AUGMENTATION
Diagnosis and treatment planning. This role has been discussed previously in this article. It is important to remember that diagnosis and treatment planning constitute a cooperative effort between the prosthodontist and the oral surgeon. Each should understand thoroughly the objectives of the treatment the other will provide, and each should participate in the diagnostic effort. Acrylic resin model/or rib adaptation. An overextended modeling-plastic impression of the ridge is made prior to surgery. This type of impression records the shape of the entire superior contour of tile ridge. From this impression, a dental stone cast (Fig. 13) is produced which is duplicated in acrylic resin (Fig. 14). This plastic model is gas sterilized, taken to the operating room, and used as a template upon which tile rib to be grafted is shaped during surgery. Care must be taken to trim the cast and the model lingually in order to allow for adequate space when forming the rib. Oral and orthopedic surgeons comment favorably on the accuracy of these models and express no need to have a direct impression of the denuded residual bone. Acrylic resin splint for skin grafting. Approximately six months following the graft of bone, an overextended modeling-plastic impression of the ridge is made. This produces a cast on which a clear plastic splint is fabricated. This splint is gas sterilized, taken to the operating roonl, and used to support a modeling-plastic impression of the surgically exposed area. This in turn is lined with a gutta-perchabased material, ~ which is used to shape the grafted skin and retain it over the surgically prepared ridge. The purpose of the lining material is to prevent an inflammatory response in the periosteal bed and to act as a passive matrix for the grafted skin. The splint containing the split-thickness graft of skin from the buttock is held in place by wires or sutures for approximately 10 days. The patient is then ready to receive initial dentures. Initial dentures. The initial dentures are begun immediately following the skin graft procedure. The custom tray used for making the secondary impression of the *Guttaform, Max Haefeli, Basel, Switzerland.
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Fig. 13. A dental stone cast of a preoperative ridge as recorded in modeling plastic. "~'he area to be trimmed to allow space for rib ntatlipulation is marked. Fig. 14. An acrylic resin model (template). It is used in the operating room as a template upon which the rib to be grafted is formed.
grafted ridge is not border molded, and alginate (irreversible hydrocolloid) is the impression material of choice. This minimizes chances of superficial irritation or pressure necrosis of the maturing tissues which might lead to connective-tissue proliferation. For the same reasons, the borders of the initial denture on the graft site are shortened (Fig. 15). This peripheral outline should be 1 to 2 mm. short of reaching the skin-mucosa junction, which is easily recognized on the cast. A noninterfering, cuspless occlusion is used in an attempt to decrease lateral occlusal forces. If possible, the operated ridge is favored by locating tile occlusal plane close to it. In an attempt to induce gradual function, the patient is instructed to wear the dentures four hours per day during the first week, six hours per day during the second week, and eight hours per day thereafter until the secondary denture is constructed. Secondary dentures. In approximately six months, new dentures can be made which cover the skin-mucosa junction and which fill the vestibule. Clinically, the skin-mucosa junction is not scarred nor is it visible on a cast. Although there are histologic differences, 15 the only clinically discernible difference between the skin and the mucosa is in the color. The secondary dentures can be made according to the philosophy of the dentist. DISCUSSION
Exact long-term assessment of the results of the bone grafts is not possible at this time. This procedure has only recently been introduced to this country. Clinical observation, radiographic survey, and east position as related to the opposing cast are the only sources of material presently available for study. Only an accurate weight measurement of the entire mandible or maxillae will yield the quantitative change in bone periodically occurring in these patients. This is not possible in people. Laboratory animal studies are not feasible for this purpose, because a model cannot be found in which to insert a denture for functional loading of the tissues. Isotope scanning techniques that have just become available may make such measurements a reality.t,, 17 The resulting ridge relationships are less than ideal. In most instances, the augmented mandibular arch is wide, especially posteriorly. This, no doubt, is the result
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Fig. 15. Initial dentures. They were placed in position immediately following removal of the skin graft splint. The denture border is shortened so that it is I to 2 ram. from the skin-mucosa junction. of rib placement and should be correctable with refinements in technique. The interridge distance becomes noticeably decreased in some patients. This usually necessitates shortening of the occlusal table and the use of acrylic resin teeth. Periods of paresthesia may be experienced. These occur over the grafted ridge and in the lower lip in mandibular graft patients. The condition does disappear with time, usually six months to one year following all surgery. Two periods of hospitalization are necessary for the bone augmentation procedure. Economically, this is not comparable with techniques performed in the dental office or in outpatient facilities. Finally, in patients undergoing bone grafting procedures, the grafted ridge must be without a prosthesis for approximately six months. This may be a social or business handicap. In most patients, however, the condition has been so severely disturbing that a prosthesis could not be worn prior to treatment anyway, and the healing period will only prolong this dentureless state. CONCLUSIONS The prosthodontist has had the opportunity to study the supporting tissues in depth. He must thoroughly understand what surgical procedures are available for changing the nature of supporting tissues, and then use this knowledge to his advantage_ in diagnosis, consultation, and treatment. He must communicate with oral surgeons on these terms. The objective of the procedures outlined is to return the tissues to the near physiologic state. This approach to treatment allows patients with deficient denture-supporting tissues to achieve function in comfort, without danger of trauma, infection, or further destruction of tissue. References I. Tallgren, A.: The Continuing Reduction of the Residual Alveolar Ridges in Complete Denture Wearers: A Mixed-Longitudinal Study Covering 25 Years, J. PaosTrtET. DENT. 27: 120-132, 1972. 2. Johnson, K.: A Clinical Evaluation of Upper Immediate Denture Procedures, J. Paos'rrt~a'. Dr~'r. 16: 799-810, 1966.
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April, 1975
3. Wictorin, L.: An Evaluation of Bone Surgery in Patients With Immediate Dentures, J. PROSTHET. DENT. 21: 6-13, 1969. 4. Payne, S. H.: A Transitional Denture, J. PRosa'HE'r. DENT. 14: 221-230, 1964. 5. Rayson, J. H., and Wesley, R. C.: An Immediate Denture Technique, J. PROSTHET. DENT. 23: 456-463, I970. 6. Lytle, R. B.: The Management of Abused Oral Tissues in Complete Denture Construction, J. P~os'raET. DENT. 7: 27-42, 1957. 7. Laney, W. R., Turlington, E. G., and Devine, K. D.: Grafted Skin as an Oral ProsthesisBearing Tissue, J. PaosTHv:r. DENT. 19: 69-79, 1968. 8. Natiella, J. R., Armitage, J. E., Greene, G. W., and Me~enaghan, M. A.: Current Evaluation of Dental Implants, J. Am. Dent. Assoc. 84: 1358-1372, 1972. 9. Topazian, R. G., Hammer, W. B., Boucher, L. J., and Hulbert, S. F.: Use of Alloplastics for Ridge Augmentation, J. Oral Surg. 29: 792-798, 1971. 10. Cooksey, D. E.: Clinical and Animal Experiments to Investigate the Healing Properties of Freeze-Dried Bone Materials in Cysts of the Jaws, Thesis, Graduate School, Georgetown University, Washington, D. C., 1954. 11. Boyne, P. J., and Cooksey, D. E.: Use of Cartilage and Bone Implants in Restoration of Edentulous Ridges, J. Am. Dent. Assoc. 71: 1426-I435, 1965. 12. Richter, H. E., Sugg, W. E., and Boyne, P. J.: Stimulation of Osteogenesis in the Dog Mandible by Autogenous Bone Marrow Transplants, J. Oral Surg. 26: 396-405, 1968. 13. Davis, W. H., Delo, R. I., Weiner, J. R., and Terry,.B.: Transoral Bone Graft for Atrophy of the Mandible, J. Oral Surg. 28: 760-765, 1970. 14. Macintosh, R. B., and Obwegeser, H. L.: Preprosthetic Surgery: A Scheme for Its Effective Employment, J. Oral Surg. 25: 397-413, 1967. 15. MSller, J. G., and J61st, O.: A Histologic Follow-up Study of Free Autogenous Skin Grafts to the Alveolar Ridge in Humans, Int. J. Oral Surg. I: 283-289, 1972. 16. Kelly', J. F., Cagle, J. D., Stevenson, J. S., and Adler, G. J.: Comparison of Osseous Allograft Systems, Int. Assoc. Dent. Res. Abst. No. 129, 1974. 17. Cagle, J. D., Kelly, J. F., Stevenson, J. S., and Adler, G. J.: t~'a'"Tc Bone Imaging for the Evaluation of MandibuIar Bone Grafts, Int. Assoc. Dent. Res. Abst. No. 308, 1974. BUREAU OF MEDICINE AND SURGERY (CODE6131 )
NAVY DEPARTi~IENT WASHINGTON,D. G. 20372
DISCUSSION Charles C. Swoope, D.D.S., M.S.D.* School o/Dentistry, University of Washington, Seattle, Wash, The article by Dr. Wilkie emphasizes the multidisclpline approach to the treatment required for denture patients with severe mechanical and biologic limitations. Effective treatment must be carefully planned in advance by the prosthodontist and the oral surgeon. Modern surgical procedures can certainly enhance the prognosis by improving the supporting tissues. Ongoing research is needed to study new ways to increase the support for dentures. Implants continue to be some~vhat unpredictable, but the use of ceramics and two-stage designs appears promising. Continued investigation and better long-term prognosis are needed before we can recommend these procedures for use in large segments of the denture population. Vestibular extension has been helpful, with both split-thickness skin grafts and buccal mucosal grafts. The tissue quality of the graft areas has been quite satisfactory with both types of grafts. Extension procedures without grafts have been somewhat disappointing. These ,,,
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Read before the Academy of Denture Prosthetics, San Francisco, Calif. *Professor and Director of Graduate Prosthodontics.
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are repositioned flaps and heal by secondary epithelialization. Without grafts, vestibular depth does not appear to be maintained over extended periods. The net gain in ridge height after a period of time has frequently been minimal. The ease of closure of the donor site and the ease of obtaining the graft have recently made lhe use of mucosal grafts more popular. It is difficult to obtain enough palatal tissue for effective vestibular extension. This type of tissue is presently used mostly in periodontal procedures to increase the zone of attached gingiva. Vestibular extensions have the obvious advantage o v e r augmentation procedures that there is no extended period in which the denture is not used. Ridge augmentations of many types have been used, and there are difficulties with most of them. The use of foreign materials has gcnerally been unsuccessful, with eroding and sloughing of the augmentation material. Bone grafts have been satisfactory in terms of successful graft "take," but are reported to be rather unsatisfactory in terms of maintaining ridge height over extended periods of time. The question of advantages of rib vs. iliac crest donor sites is still unanswered. The additional problem of a patient being without a denture for months is ahnost insurmountable. It is even difficult to persuade patients to leave dentures out overnight prior to making impressions. Following placement of initial dentures over the bone graft, there is still rapid ~:hange which requires considerable maintenance, such as multiple relines. In addition, the secondary procedure of vestibular extension is required in many instances. The vestibule is usually shortened while obtaining enough tissue to cover the added graft material on the ridge crest. The initial dentures are usually remade about six months after the vestibular extension. It is important to emphasize patient selection. M a n y patients have very poor ridges yet function quite adequately with complete dentures. Diagnosis must be based on more than physical characteristics of the residual ridge. The scope of the preceding article was limited by presentation time, and this should not be taken to imply that other patient factors are not important. Conservative procedures, such as massage and tissue conditioning, can result in considerable improvement, and these measures should be exhausted before extensive surgical preparation is undertaken. Many patients who could benefit from augmentation procedures are older individuals w h o h a v e adjusted to using dentures. They frequently have physical and financial contraindications to extensive surgery. The cost of augmentation followed by vestibular extension is considerable. The primary indication for surgery should be unsatisfactory function and continued problems with a prosthesis that is adequate for the conditions present. If the existing dentures are technically inadequate, it i s difficult to define the need for surgical correction. If the existing denture is deficient in stability, extensions, and so on, it is difficult to use it to predict the function of a properly constructed denture and the necessity for surgery. With vestibular extension, new dentures and a period of observation are in order. If the problems persist after several months, the patient requests to proceed with the surgery and the denture is subsequently relined. We know the patient will have improved function with a new denture and even greater improvement with surgery and a new denture. If the existing denture is poor, it is not possible to predict whether the patient will be satisfied with the improvement of the new denture alone. The period of evaluation provides the information to decide if the surgery represents ~ good investment for the patient. If the existing dentures are reasonably adequate and problems exist, then surgery can precede construction of the new dentures. D r . Wilkie should be complimented on his article. It is helpful for us to be reminded of the procedures at our disposal to provide an improved level of patient care. We can no longer treat these patients alone, but need the cooperation and assistance of our colleagues in other disciplines. DEPARTMENT OF PROSTHODONTICS SCHOOL OF DENTISTRY
UNIVEaSITY OF WASr~fNOTON SEATTLE, WASH. 98195
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The .role of the prosthoaontist In preprosthetic surgery, Noel O. Wilkie,.D,D.S.* Naval Graduate Dental Sctzoot, NationaI Navat Medical Center, Bethesdai Md.
Pesent-day
dental literature, especially that of oral surgery and prosthetic dentistry, is repeatedly emphasizing the problem of idiopathic changes in the supporting tissues for complete dentures. These numerous reports and studies stress the nearly epidemic pi~oportions of the problem as they search for unknown etiologic factors, describe the nature of the problem in detail, and propose many different means of treatment. The bone of the residual ridge seems to be the focus of the problem. Although great strides have been made toward preservation of this bone, in the future, the edentulous maxillae or mandible that is unable to support complete dentures or at best support dentures only with great difficulty will receive more attention. In addition, more readily available hetalth-care benefits and epidemiologic studies will show alveolar bone loss to be a major health problem now and in the future. :One solution to this problem is surgical intervention in conjunction with prosthetic rehabilitation. As this solution is presented, three contributions arising from it will be discussed at length. They are: (1) denture stability is influenced by soft tissuesas well as bone, and conclusions are made concerning conditions of the soft tissues which are most favorable to stability; (2) diagnostic criteria are outlined which lead to more critical evaluation of the denture-supporting soft tissues; and (3) recently developed preprosthetic surgical procedures with emphasis on autogenous r i b grafts are introduced into the literature of prosthodontics.
HISTORY OF THE PROBLEM Studies of the alveolar bone, the residual edentulous ridge, and the supporting mucosal tissues have revealed the following facts. (1) The alveblar bone in individuals with natural teeth is labile in nature. The
The opinions or assertions contained herein are those of the author and are not to be construed as-official or a s--Feflecting the views of the Navy Department or the naval service at large. Read before the Academy•of Denture Prosthetics, San Francisco, Calif. **Captain (DC) USN; formerly, Chief, Complete Denture Division, Prosthodontics Department.
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response of this bone to stimuli, normal or abnormal, varies from individual to individual, and this response is not predictable. This premise is important, because it gives us a clue to the nature of our problem before the individual becomes edentulous. (2) The response of the alveolar bone to tooth loss and subsequent function under dentures varies from individual to individual, but it can be predicted that the response will be some degree of reduction of the bone of the residual ridges. (3) Many observers have attempted without success to correlate changes in the residual ridges to age, sex, systemic and endocrine disturbances, pre-extraction periodontal status, occlusion in dentures, denture base materials, immunologic response, habit patterns, lack of periodic denture maintenance or reconstruction, and other biologic and iatrogenic factors. Few, if any, studies have attempted to correlate these same factors with pathognomonic changes in the supporting and overlying mucosal tissues. The causes Of these problems must be discovered in order to arrive at valid preventive approaches in treatment. (4) It can be predicted that the amount of reduction will be greater in the mandibular ridge than in the maxillary ridge. Tallgren, 1 in a longitudinal study, found the loss in the mandibular ridge to be four times greater. This tells us where we will see the majority of our problems. Coincidentally, it is the mandibular ridge that has the least amount of support for dentures in the first place. (5) Tallgren 1 also observed a greater loss of bone tissue in the anterior ridge region than in the posterior region. This complicates treatment by prosthetic means alone, because we are forced to use inclined planes for our supporting bases. (6) It can be predicted that the rate of bone loss will be most rapid during the first year. ~ This rate of bone loss seems to be less (there is a smaller amount of ridge reduction) if the ridges are placed in function directly following extraction. Johnson 2 and Wictorin a reported such results with immediate maxillary dentures. It appears that immediate functioning of all areas, such as occurs under transitional dentures, likewise encourages the preservation of the maximum amounts of bone. Longitudinal studies reporting the effects of function under transitional dentures have not been reported; however, personal observations and those of Payne 4 and of Rayson and Wesley 5 seem to verify slowing in the rate of bone loss. (7) The response in the mucosaI tissues varies as well. The response can be slight displacement of the mucosa within physiologic limits. This condition is reversible by rest. A more severe response will be infiltration of inflammatory cells into the subepithelial connective tissues. This condition may be reversed by removal of the dentures or by alternating periods of removal with periods of wearing the denture with tissue-conditioning materials. Fibrous connective-tissue proliferation with add{tional numbers of inflammatory cells in the submucosa is representative of the most severe response of the mucosal supporting tissues. This is almost always an irreversible condition, and surgical intervention may have to be recommended. It can be suspected that an extensive change in the mucosal and submucosal tissues may be either the predecessor to or occur in conjunction with the most severe fonals of bone loss. HISTORY OF SOLUTIONS TO THE PROBLEM
The treatment of these tissue problems has generally fallen into three philosophies: No tissue alteration. The existing tissue form and structure are recognized but are
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not altered in any manner, and the prosthetic treatment is adapted to suit this set of conditions. Such prosthetic treatment includes specialized impression techniques, changes in occlusal patterns, specialized tooth forms, metallic denture base materials, and other nonroutine techniques. Nonsurgicat and surgical management of soft tissues. The soft tissues may be assessed as having reversible conditions. In this:situation, initiation of prosthetic treatment will include instructions for periodic ~,emoval of existing dentures, correction of the occlusion in the existing dentures, and use of tissue-conditioning materials, as advocated by Lytle2 If tissue examinati6"n reveals nonreversible tissue conditions, surgery may be recommended. In past years, the emphasis of this preprosthetic surgery has been on vestibular alteration, with specia ! attention given to a quantitative deepening rather than a qualitative change in the nature of the soft tissues. The most frequently cited surgical procedure for changing the nature of the tissues is the use of grafted autogenous skin. ~ The most common site for this procedure is the mandibular buccolabial region, and frequently the extent of the graft rises to the inner surface of the lower lip. In the process of refining gingival surgery, periodontists have stimulated interest in surgical techniques which increase amounts of attached mucosa. Now the literature of oral surgery is beginning to report mucosal transplants, use of freeze-dried homografts of skin, and secondary epithelialization procedures which have the objective of changing the nature as well as the extent of prosthesis-bearing tissues. Surgical management of the supporting bone. In some individuals, changes in the supporting hard and soft tissues are so severe as to require alterations in or on the residual bone. Mechanical fixation of various electropassive metals, mainly chromiumcobalt-nickel and titanium alloys and tantalum, on or into the residual bone has been frequently reported. For approximately 25 years, the subperiosteal metallic implant has been with us. A critical review of the research, available information, and clinical results of this type of implant was reported by the University of Buffalo at the direction of the Council on Dental Materials and Devices of the American Dental Association. s This report is not encouraging and points out the need for a continuing research effort with this type of implant. Endosteal metallic implants of the pin, screw, staple, and blade varieties are currently being popularized. Development of better techniques for study, adequately controlled longitudinal studies, and careful peer review of the trairiing for use and clinical application are imperative if endosteal implants are to be accepted as a future solution to our problem. Subperiosteal implants of alloplastic materials have recently been introduced2 The most common of thesehave been vitreous carbon and ceramic materials. Although ongoing animal research is being conducted, no conclusive evidence can be found a s a basis for introducing these materials into everyday use in human subjects at this time. Augmentation of the residual ridge with bone has been a sought-after approach, because biocompatability of the graft and the host site is virtually assured. Cryopreserved (freeze-dried) cartilage and bone were used successfully as allografts in artificially created intraoral defects in 1953 by Cooksey? ° Boyne and Cooksey~ later used freeze-dried bone and cartilage subperiosteally on the ridge crest both experimentally in dogs and clinically in human patients. Clinical and radiographic evaluation for as long as four and a half years indicated that these grafts became an integral part of the ridge and were capable of supporting complete
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denture prostheses. Richter, Sugg, and Boyne 12 had success in an experiment with autogenous hematopoietic bone marrow held in a chrome-c0balt cage lined with a cellulose acetate Millipore filter. This filter effectively prohibited invasion of connective tissue. These' experiments on the mandibles of dogs resulted in the formation of supracortical cancellous bone. The technique has subsequently been used successfully in man to repair discontinuity defects in bone traumatized from war wounds and accidents. Most recently, Davis and his associates 1" have brought to this country surgica ! techniques introduced by Prof. Hugo Obwegeser of Zurich, Switzerland. This surgica 1 method utilizes autogenous block grafts from the ilium or, more commonly, two ribs placed via a transoral approach in either the mandible or the maxillae. Almost always, a subsequent surgical procedure is a vestibuloplasty with a splitthickness graft of skin. If the procedures have been directed toward improvement of the mandible, a lowering of the entire floor of the mouth is carried out simultaneously with ridge skin grafting, as advocated by Macintosh and Obwegeser. TM Results of these procedures have been encouraging. Postgrafted patients h a v e been wearing prostheses under observation for more than four years. In these patients, it is expected that 40 to 50 per cent of the vertical height of bone gained at surgery will be lost during the first 12 to 18 months. Terry* has followed a great number of these patients postoperatively and observed a lessened resorption rate after this period, with the remaining residual bone appearing to become more dense radiographically. A 10 year longitudinal study is now in progress which will critically evaluate this surgical technique. Attendant prosthetic procedures for these patients are very specific and are described in detail herein. THE INFLUENCE OF SOFT TISSUES ON DENTURE STABILITY
Certain observations have been made during the prosthetic treatment of patients who have undergone preprosthetic surgery. T h e first is that a residual ridge which has had only an autograft of bone and not the skin graft or "mouth-floor-plasty" still has very mobile tissues. Record bases placed on these ridges are not stable, and it is difficult to assess retention. The second observation is that the initial complete denture which is made following bone and skin grafting is very stable. This denture has planned foreshortened borders in its entire periphery, and it contacts only on the grafted skin, not mucosal tissues. It purposely does not extend into the vestibular areas. In spite of this, stability of the denture is greatly improved. Finally, if the patients' needs dictate, necessary preprosthetic procedures may be those which change the nature of the supporting soft tissues only and not bone. The initial dentures in these patients demonstrate marked improvements in stability. Although not so easily observed, retention seems to improve as well. From these observations, one can conclude that contour and amount of bone are not so influential toward denture stability as are the nature and attachment of the soft tissues to that bone. The ideal attachment should be surface epithelium with minimal amounts of connective tissue interposed between it and the periosteum. From the prosthetic standpoint, grafted skin should not line the vestibule or inner lip (Fig. 1 ). Normal oral mucosa, which is resilient and which secretes its normal *B. C. Terry: Preprosthetic Surgery. Unpublished report.
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Fig. 1. Vestibular deepening with skin graft lining the entire vestibule and inner lower lip. Fig. 2. "Mouth-floor-plasty" with a split-thickness autogenous skin graft short of the vestibule. Advantages are normal meniscus formation and lack of scar tissue at denture border.
Fig. 3. Incipient fissure at the junction of attached and unattached mucosa (arrow). Fig. 4. Fissuring within attached mucosa. fluids, serves to form a much better meniscus at the denture border than does skin (Fig. 2). Considering this, precise diagnostic criteria for the soft tissues will be set forth. Equally good criteria have been developed for bone assessment, but this should not be given a disproportionate share of the diagnostic effort. A diagnosis developed from information about these tissues will provide the ideal common meeting ground from which the oral surgeon and the prosthodontist can plan treatment. DIAGNOSTIC CRITERIA USED IN TISSUE EVALUATION Soft-tissue assessment
Amounts of attached mucosa. T h e amount of attached mucosa should be no less than a norm, which covers the crest and one third to one half of the slopes of each ridge. Lesser amounts may be prevalent in some areas but should not be accepted as a general norm. Fissuring. Fissuring is commonly seen at the junction of the attached and unattached mucosa (Fig. 3). It can occur within each mucosal area as well (Figs. 4 and 5). It may be ulcerated (Fig. 5) but generally is not. The fissure is a signal of potential hyperplasia of the tissues and, if severe, can be eliminated by mueosal and skin grafts, freeze-dried skin allografts, or secondary epithelialization procedures. It
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Fig. 5. An ulcerated fissure within unattached mucosa. Fig. 6. Attached mucosa which can be folded over the unattached mucosa.
Fig. 7. A clear plastic template showing folding with function. Fig. 8. Tissues corrected with a submucous resection technique.
should be understood that secondary epithelialization procedures regress up to 50 per cent. This is no problem in the treatment of fissuring, because usually there is adequate mucosa where it is needed. Folding. This usually is the next sequence if the fissuring problem worsens. It indicates hyperplasia of the submucosal connective tissues on one or both sides of the fissure (Fig. 6). It seems to be self-perpetuating, especially with an overlying denture. It can be seen extremely well in function under a clear plastic template placed as a denture base (Fig. 7). If there is adequate underlying bone, the fissure and folds of tissue should be eliminated by the surgical procedure known as submucous resection (Fig. 8), and the surgical technique is well outlined by Macintosh and Obwegeser. 14 This removes redundant connective tissue between the mucosa and periosteum on the lateral side of the ridge and readapts the mucosa directly to the periosteum up to the point of deepest vestibular height. The submucous resection is most commonly used in the maxillary anterior ridge region. Mobility of tissue. An excessive amount of soft tissue is a reflection of severe changes in the supporting bone (Fig. 9). This results in tissue mobility. The tissues may demonstrate scarring, great amounts of connective-tissue proliferation, and decreased amounts of attached mucosa. Bone correction may not be necessary, but
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Fig. 9. Extremely mobile mucosal tissues indicating severe resorption of bone. Fig. 10. The floor of the mouth in repose lies above the ridge crest. extensive soft-tissue procedures, such as excision of the connective tissue followed by secondary epithelialization or mucosal or skin grafts, should be the treatment of choice. Position of the mouth floor. Should the m o u t h floor in repose lie near the level of the ridge crest or above (Fig. l e), a "mouth-floor-plasty" should be recommended. These very mobile tissues, consisting of connective, vascular, muscular, and glandular tissues, will have to be permanently lowered, with the muscles affixed at the lowest possible level on the inner aspects of the mandible. Bone assessment
A pantographic and lateral cephalometric radiographic survey is necessary to assess the bone. Soft-tissue height in relation to the residual bone can be visualized by placing a strip of tinfoil in the existing dentures or in a plastic template which covers the ridges. Maxillary survey. When the residual bone level is seen to be approaching the level of the anterior nasal spine and generalized resorption is so severe that a nearly equal plane exists between the vestibule and the palate (Fig. l 1), the diagnostic team should consider bone grafting. Without bone augmentation, there can be no vestibule and no obstruction to lateral or anterior posterior movement of the denture. It has also been observed that retention of the maxillary denture is minimal owing to the ease with which the palatal seal can be broken. In these patients, even gravity forces are enough to make wearing a denture nearly impossible. Mandibular survey. If the horizontal body of the mandible demonstrates a thickness no greater than 1 to 1.5 cm. when viewed in the radiograph (Fig. 12), bone augmentation procedures should be considered. Without such augmentation, vestibuloplasty and lowering of the mouth floor could gain little depth. A greater danger is that lesser amounts of residual bone are susceptible to pathologic fracture. Interridge distance survey. As a final determinant, the interridge distance should be assessed at the tentative vertical dimension of occlusion. This can be visualized on properly mounted casts and will reveal the mechanical difficulties one must labor under should no augmentation procedures be attempted.
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Fig. 1I. A radiographic survey of the maxillae. Note that the residual bone height is level with the anterior nasal spine and base (center) of the palate. Fig. 12. A Panorex radiographic survey of a mandible. The measured thickness of the body of the mandible is less than 1.5 cm. THE ROLE OF THE PROSTHODONTIST IN SURGICAL RIDGE AUGMENTATION
Diagnosis and treatment planning. This role has been discussed previously in this article. It is important to remember that diagnosis and treatment planning constitute a cooperative effort between the prosthodontist and the oral surgeon. Each should understand thoroughly the objectives of the treatment the other will provide, and each should participate in the diagnostic effort. Acrylic resin model/or rib adaptation. An overextended modeling-plastic impression of the ridge is made prior to surgery. This type of impression records the shape of the entire superior contour of tile ridge. From this impression, a dental stone cast (Fig. 13) is produced which is duplicated in acrylic resin (Fig. 14). This plastic model is gas sterilized, taken to the operating room, and used as a template upon which tile rib to be grafted is shaped during surgery. Care must be taken to trim the cast and the model lingually in order to allow for adequate space when forming the rib. Oral and orthopedic surgeons comment favorably on the accuracy of these models and express no need to have a direct impression of the denuded residual bone. Acrylic resin splint for skin grafting. Approximately six months following the graft of bone, an overextended modeling-plastic impression of the ridge is made. This produces a cast on which a clear plastic splint is fabricated. This splint is gas sterilized, taken to the operating roonl, and used to support a modeling-plastic impression of the surgically exposed area. This in turn is lined with a gutta-perchabased material, ~ which is used to shape the grafted skin and retain it over the surgically prepared ridge. The purpose of the lining material is to prevent an inflammatory response in the periosteal bed and to act as a passive matrix for the grafted skin. The splint containing the split-thickness graft of skin from the buttock is held in place by wires or sutures for approximately 10 days. The patient is then ready to receive initial dentures. Initial dentures. The initial dentures are begun immediately following the skin graft procedure. The custom tray used for making the secondary impression of the *Guttaform, Max Haefeli, Basel, Switzerland.
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Fig. 13. A dental stone cast of a preoperative ridge as recorded in modeling plastic. "~'he area to be trimmed to allow space for rib ntatlipulation is marked. Fig. 14. An acrylic resin model (template). It is used in the operating room as a template upon which the rib to be grafted is formed.
grafted ridge is not border molded, and alginate (irreversible hydrocolloid) is the impression material of choice. This minimizes chances of superficial irritation or pressure necrosis of the maturing tissues which might lead to connective-tissue proliferation. For the same reasons, the borders of the initial denture on the graft site are shortened (Fig. 15). This peripheral outline should be 1 to 2 mm. short of reaching the skin-mucosa junction, which is easily recognized on the cast. A noninterfering, cuspless occlusion is used in an attempt to decrease lateral occlusal forces. If possible, the operated ridge is favored by locating tile occlusal plane close to it. In an attempt to induce gradual function, the patient is instructed to wear the dentures four hours per day during the first week, six hours per day during the second week, and eight hours per day thereafter until the secondary denture is constructed. Secondary dentures. In approximately six months, new dentures can be made which cover the skin-mucosa junction and which fill the vestibule. Clinically, the skin-mucosa junction is not scarred nor is it visible on a cast. Although there are histologic differences, 15 the only clinically discernible difference between the skin and the mucosa is in the color. The secondary dentures can be made according to the philosophy of the dentist. DISCUSSION
Exact long-term assessment of the results of the bone grafts is not possible at this time. This procedure has only recently been introduced to this country. Clinical observation, radiographic survey, and east position as related to the opposing cast are the only sources of material presently available for study. Only an accurate weight measurement of the entire mandible or maxillae will yield the quantitative change in bone periodically occurring in these patients. This is not possible in people. Laboratory animal studies are not feasible for this purpose, because a model cannot be found in which to insert a denture for functional loading of the tissues. Isotope scanning techniques that have just become available may make such measurements a reality.t,, 17 The resulting ridge relationships are less than ideal. In most instances, the augmented mandibular arch is wide, especially posteriorly. This, no doubt, is the result
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Fig. 15. Initial dentures. They were placed in position immediately following removal of the skin graft splint. The denture border is shortened so that it is I to 2 ram. from the skin-mucosa junction. of rib placement and should be correctable with refinements in technique. The interridge distance becomes noticeably decreased in some patients. This usually necessitates shortening of the occlusal table and the use of acrylic resin teeth. Periods of paresthesia may be experienced. These occur over the grafted ridge and in the lower lip in mandibular graft patients. The condition does disappear with time, usually six months to one year following all surgery. Two periods of hospitalization are necessary for the bone augmentation procedure. Economically, this is not comparable with techniques performed in the dental office or in outpatient facilities. Finally, in patients undergoing bone grafting procedures, the grafted ridge must be without a prosthesis for approximately six months. This may be a social or business handicap. In most patients, however, the condition has been so severely disturbing that a prosthesis could not be worn prior to treatment anyway, and the healing period will only prolong this dentureless state. CONCLUSIONS The prosthodontist has had the opportunity to study the supporting tissues in depth. He must thoroughly understand what surgical procedures are available for changing the nature of supporting tissues, and then use this knowledge to his advantage_ in diagnosis, consultation, and treatment. He must communicate with oral surgeons on these terms. The objective of the procedures outlined is to return the tissues to the near physiologic state. This approach to treatment allows patients with deficient denture-supporting tissues to achieve function in comfort, without danger of trauma, infection, or further destruction of tissue. References I. Tallgren, A.: The Continuing Reduction of the Residual Alveolar Ridges in Complete Denture Wearers: A Mixed-Longitudinal Study Covering 25 Years, J. PaosTrtET. DENT. 27: 120-132, 1972. 2. Johnson, K.: A Clinical Evaluation of Upper Immediate Denture Procedures, J. Paos'rrt~a'. Dr~'r. 16: 799-810, 1966.
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3. Wictorin, L.: An Evaluation of Bone Surgery in Patients With Immediate Dentures, J. PROSTHET. DENT. 21: 6-13, 1969. 4. Payne, S. H.: A Transitional Denture, J. PRosa'HE'r. DENT. 14: 221-230, 1964. 5. Rayson, J. H., and Wesley, R. C.: An Immediate Denture Technique, J. PROSTHET. DENT. 23: 456-463, I970. 6. Lytle, R. B.: The Management of Abused Oral Tissues in Complete Denture Construction, J. P~os'raET. DENT. 7: 27-42, 1957. 7. Laney, W. R., Turlington, E. G., and Devine, K. D.: Grafted Skin as an Oral ProsthesisBearing Tissue, J. PaosTHv:r. DENT. 19: 69-79, 1968. 8. Natiella, J. R., Armitage, J. E., Greene, G. W., and Me~enaghan, M. A.: Current Evaluation of Dental Implants, J. Am. Dent. Assoc. 84: 1358-1372, 1972. 9. Topazian, R. G., Hammer, W. B., Boucher, L. J., and Hulbert, S. F.: Use of Alloplastics for Ridge Augmentation, J. Oral Surg. 29: 792-798, 1971. 10. Cooksey, D. E.: Clinical and Animal Experiments to Investigate the Healing Properties of Freeze-Dried Bone Materials in Cysts of the Jaws, Thesis, Graduate School, Georgetown University, Washington, D. C., 1954. 11. Boyne, P. J., and Cooksey, D. E.: Use of Cartilage and Bone Implants in Restoration of Edentulous Ridges, J. Am. Dent. Assoc. 71: 1426-I435, 1965. 12. Richter, H. E., Sugg, W. E., and Boyne, P. J.: Stimulation of Osteogenesis in the Dog Mandible by Autogenous Bone Marrow Transplants, J. Oral Surg. 26: 396-405, 1968. 13. Davis, W. H., Delo, R. I., Weiner, J. R., and Terry,.B.: Transoral Bone Graft for Atrophy of the Mandible, J. Oral Surg. 28: 760-765, 1970. 14. Macintosh, R. B., and Obwegeser, H. L.: Preprosthetic Surgery: A Scheme for Its Effective Employment, J. Oral Surg. 25: 397-413, 1967. 15. MSller, J. G., and J61st, O.: A Histologic Follow-up Study of Free Autogenous Skin Grafts to the Alveolar Ridge in Humans, Int. J. Oral Surg. I: 283-289, 1972. 16. Kelly', J. F., Cagle, J. D., Stevenson, J. S., and Adler, G. J.: Comparison of Osseous Allograft Systems, Int. Assoc. Dent. Res. Abst. No. 129, 1974. 17. Cagle, J. D., Kelly, J. F., Stevenson, J. S., and Adler, G. J.: t~'a'"Tc Bone Imaging for the Evaluation of MandibuIar Bone Grafts, Int. Assoc. Dent. Res. Abst. No. 308, 1974. BUREAU OF MEDICINE AND SURGERY (CODE6131 )
NAVY DEPARTi~IENT WASHINGTON,D. G. 20372
DISCUSSION Charles C. Swoope, D.D.S., M.S.D.* School o/Dentistry, University of Washington, Seattle, Wash, The article by Dr. Wilkie emphasizes the multidisclpline approach to the treatment required for denture patients with severe mechanical and biologic limitations. Effective treatment must be carefully planned in advance by the prosthodontist and the oral surgeon. Modern surgical procedures can certainly enhance the prognosis by improving the supporting tissues. Ongoing research is needed to study new ways to increase the support for dentures. Implants continue to be some~vhat unpredictable, but the use of ceramics and two-stage designs appears promising. Continued investigation and better long-term prognosis are needed before we can recommend these procedures for use in large segments of the denture population. Vestibular extension has been helpful, with both split-thickness skin grafts and buccal mucosal grafts. The tissue quality of the graft areas has been quite satisfactory with both types of grafts. Extension procedures without grafts have been somewhat disappointing. These ,,,
,,
.
Read before the Academy of Denture Prosthetics, San Francisco, Calif. *Professor and Director of Graduate Prosthodontics.
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are repositioned flaps and heal by secondary epithelialization. Without grafts, vestibular depth does not appear to be maintained over extended periods. The net gain in ridge height after a period of time has frequently been minimal. The ease of closure of the donor site and the ease of obtaining the graft have recently made lhe use of mucosal grafts more popular. It is difficult to obtain enough palatal tissue for effective vestibular extension. This type of tissue is presently used mostly in periodontal procedures to increase the zone of attached gingiva. Vestibular extensions have the obvious advantage o v e r augmentation procedures that there is no extended period in which the denture is not used. Ridge augmentations of many types have been used, and there are difficulties with most of them. The use of foreign materials has gcnerally been unsuccessful, with eroding and sloughing of the augmentation material. Bone grafts have been satisfactory in terms of successful graft "take," but are reported to be rather unsatisfactory in terms of maintaining ridge height over extended periods of time. The question of advantages of rib vs. iliac crest donor sites is still unanswered. The additional problem of a patient being without a denture for months is ahnost insurmountable. It is even difficult to persuade patients to leave dentures out overnight prior to making impressions. Following placement of initial dentures over the bone graft, there is still rapid ~:hange which requires considerable maintenance, such as multiple relines. In addition, the secondary procedure of vestibular extension is required in many instances. The vestibule is usually shortened while obtaining enough tissue to cover the added graft material on the ridge crest. The initial dentures are usually remade about six months after the vestibular extension. It is important to emphasize patient selection. M a n y patients have very poor ridges yet function quite adequately with complete dentures. Diagnosis must be based on more than physical characteristics of the residual ridge. The scope of the preceding article was limited by presentation time, and this should not be taken to imply that other patient factors are not important. Conservative procedures, such as massage and tissue conditioning, can result in considerable improvement, and these measures should be exhausted before extensive surgical preparation is undertaken. Many patients who could benefit from augmentation procedures are older individuals w h o h a v e adjusted to using dentures. They frequently have physical and financial contraindications to extensive surgery. The cost of augmentation followed by vestibular extension is considerable. The primary indication for surgery should be unsatisfactory function and continued problems with a prosthesis that is adequate for the conditions present. If the existing dentures are technically inadequate, it i s difficult to define the need for surgical correction. If the existing denture is deficient in stability, extensions, and so on, it is difficult to use it to predict the function of a properly constructed denture and the necessity for surgery. With vestibular extension, new dentures and a period of observation are in order. If the problems persist after several months, the patient requests to proceed with the surgery and the denture is subsequently relined. We know the patient will have improved function with a new denture and even greater improvement with surgery and a new denture. If the existing denture is poor, it is not possible to predict whether the patient will be satisfied with the improvement of the new denture alone. The period of evaluation provides the information to decide if the surgery represents ~ good investment for the patient. If the existing dentures are reasonably adequate and problems exist, then surgery can precede construction of the new dentures. D r . Wilkie should be complimented on his article. It is helpful for us to be reminded of the procedures at our disposal to provide an improved level of patient care. We can no longer treat these patients alone, but need the cooperation and assistance of our colleagues in other disciplines. DEPARTMENT OF PROSTHODONTICS SCHOOL OF DENTISTRY
UNIVEaSITY OF WASr~fNOTON SEATTLE, WASH. 98195