Changes in contour of the maxillary alveolar process under immediate dentures. A longitudinal clinical and x-ray cephalometric study covering 5 years

Measurement of ridge alterations following tooth removal: a radiographic study in humans

OBJECTIVE

The aim of this study was a radiographic mesiodistal analysis of the shape of the bone crest 3 months after tooth removal.

MATERIAL AND METHODS

One hundred single tooth extractions were performed on 100 patients because of orthodontic or prosthetic causes. Bite blocks were used for two radiographs: one on the day of extraction and the other after healing of the socket, 3 months later. These X-rays were used to determine: (1) the most apical distance of alveolar ridge resorption, with baseline as the line between bone-to-teeth contact (the greatest distance in bone resorption height) and (2) the mesiodistal distance (MDD) and mesial and distal angles arising after bone tissue modeling.

RESULTS

Significant differences (P<0.05) emerged between the MDDs of multiple- [8 mm, 95% confidence interval (CI): 6.09, 9.90] and single-root teeth (5.60 mm, 95% CI: 4.80, 6.50). However, mesial or distal angles or the most apical distance of alveolar ridge resorption did not differ (mean distance in height=4.32 mm, 95% CI: 3.85, 4.78; mean angle=24 degrees ).

CONCLUSIONS

In this study, the post-extraction mesiodistal bone distance between teeth adjacent to the edentulous ridge depends on the size of the edentulous space. Nevertheless, the distance does not affect the distance in bone loss height. The distance of bone resorption height reaches a balance at the midpoint, which we consider indicative of stable healing. This resorption process must be considered when placing dental implants in fresh extraction sockets, especially in aesthetic sites, because the implant surfaces could be exposed after 3 months.

Platelet rich plasma to facilitate wound healing following tooth extraction

Following tooth removal bone formation normally takes 16 weeks and may result in less than adequate volume for the necessary reconstruction. Platelet rich plasma (PRP) has been promoted as an effective method for improving bone formation. Its use is often expensive, time consuming, or not clinically convenient for the patient and/or clinician. This study examines a simple method for obtaining a "Buffy Coat"-PRP (BC-PRP) and its effect on bone healing following the removal of bilateral mandibular 3rd molars. Subtraction digital radiography and CT scan analysis were used to track changes in radiographic density at PRP treated sites in comparison to ipsilateral non-PRP treated sites. PRP treated sites demonstrated early and significant increased radiographic density over baseline measurements following tooth removal. The greatest benefit of PRP is during the initial 2-week postoperative healing time period (P < .001). During weeks 3 though 12, BC-PRP treatment resulted in significant (P < .0001) increases in bone density compared to control, but there was no significant interaction between time and treatment (P > .05). For the entire time period (0-25 weeks) PRP treatment was significant (P < .0001) and time was significant (P < .0001) but there was no significant interaction (P > .05) between the effect of PRP treatment and time. It required 6 weeks for control extraction sites to reach comparable bone density that PRP treated sites achieved at week 1. Postoperative pain, bleeding, and numbness were not significantly affected by BC-PRP application. Results suggest that this simple technique may be of value to clinicians performing oral surgery by facilitating bone regeneration following tooth extraction.

Anatomically guided implant site preparation technique at molar sites

Immediate postextraction implant placement in the areas of multiradicular teeth is a difficult procedure in view of having to place the implant in an ideal position without jeopardizing its initial stability. The surgeon often faces the problem of directing the initial osteotomy in the medial portion of the alveolus with the difficulty of engaging the inter-radicular septum of the extraction socket. The drill may slip continually leading to an inaccurate site preparation, and consequently to a deficient implant insertion. The fixture is often placed directly into either one of the extraction sockets of the tooth to be replaced. The anatomically guided site preparation technique is a very useful tool to perform implant placement in the areas of multiradicular teeth. This approach of implant insertion consists of a progressive preparation of the implant site using the anatomy and geometry of the root of the multiradicular teeth to be extracted as a reference and as an aid to engage the inter-radicular septum. This places the implants in a favorable and proper position from a biomechanical and occlusal standpoint. The objective of this article is to describe the anatomically guided implant site preparation technique as an aid to favorably place dental implants in multiradicular teeth postextraction.

Morphologic changes of the nasopalatine canal related to dental implantation: a radiologic study in different degrees of absorbed maxillae

BACKGROUND

Implant rehabilitation of the edentulous anterior maxilla remains a complex restorative challenge. Intricate preexisting anatomy dictates meticulous and accurate osteotomy planning. With progressive bone loss, the alveolar crest may approach anatomic structures. The nasopalatine nerve and vessels may ultimately emerge from the ridge crest. The radiologic changes of the nasopalatine canal were evaluated in different resorption phases of the premaxilla alveolus with regard to dental implantation.

METHODS

The study consisted of 207 subjects who had maxillary computed tomography scans before dental implantation. The Lekholm and Zarb classification was used to divide images according to the residual bony ridge: Class A (control group) and classes B to E (study group). Anatomic mapping of the nasopalatine canal structure was carried out in both groups.

RESULTS

The canal diameter was wider along the degree of ridge resorption from classes A to E in all dimensions, mainly in the palatal opening (P <0.01), middle area (P <0.001), and nasal area. The mean diameter of the enlargement was 1.8 mm, which reached 5.5 +/- 1.08 mm (P <0.01) in type E bone. In the severely resorbed ridges (classes C through E), when the palatal opening was situated on the ridge, it occupied a mean of 35.6% (13% to 58%) of the area devoted to implant placement. Tooth loss was the main reason for ridge resorption (P <0.01).

CONCLUSIONS

Canal diameter enlargement was greater anteriorly to the ridge and posteriorly to the palatal bone, mainly because of tooth extraction. The atrophy of disuse may influence surrounding structures, similar to the maxillary sinus tendency to expand into surrounding bone mainly after tooth loss.

Orthodontic Space Opening in Patients with Congenitally Missing Lateral Incisors

OBJECTIVE

To determine the best time to begin orthodontic treatment for patients scheduled for implants to replace congenitally missing upper lateral incisors. The aim of timing is to maximize the amount of bone available for implant insertion and to improve incisors inclination.

MATERIALS AND METHODS

Seventy-three plaster casts of 14 patients with 26 missing lateral incisors were cross sectioned in the center of the planned insertion of the implant, and the implant profile was projected into the area at three different times: T1--beginning of orthodontic treatment, T2-- end of orthodontic treatment, and T3--implant insertion. Deficiency of alveolar ridge volume needed for implantation was determined by Leica Quin analySIS software.

RESULTS

An increase of ridge-volume deficiency from 0.26 mm(2) at T1 to 3.77 mm(2) at T3 was found. During orthodontic treatment the incisors protruded about 9.4 degrees (differing from the O1-NA standard of 7.5 degrees ). To ensure optimal esthetic and functional implantation results, time management concerning orthodontic treatment has to be done carefully.

CONCLUSIONS

To avoid a high degree of alveolar bone atrophy and the risk of relapse and retreatment, orthodontic treatment involving tooth movement should not be initiated before the age of 13 years. Furthermore, it is important to maintain anchorage of the upper incisors because high incisor proclination causes extra-axial stress on the implant. An interdisciplinary approach is essential to provide the best treatment outcome.

Treatment Options Following Single-Rooted Tooth Removal: A Literature Review and Proposed Hierarchy of Treatment Selection

BACKGROUND

Alveolar bone changes following tooth extraction have been well documented and have given rise to a number of treatment approaches. Included in these approaches are placement of various grafting materials, immediate implant placement, and a combination of both.

METHODS

A review of all pertinent literature discussing regenerative therapy at the time of tooth extraction or immediate implant placement with or without concomitant regenerative therapy was carried out.

RESULTS

A clinically-based hierarchy of treatment selection following extraction of single rooted teeth is proposed, based upon the available literature and clinical experience. The role of patient phenotype is considered.

CONCLUSION

Utilization of the proposed hierarchy of treatment selection affords a logical framework within which to predictably treat a variety of patients.

Maxillary lateral incisor implants: Planning with the aid of orthodontics

Implants are commonly used to replace congenitally missing lateral incisors in adolescent orthodontic patients. However, these restorations are often challenging for the orthodontist, surgeon, and restorative dentist. In some patients the space across the alveolar crest is too narrow to permit the surgeon to place the implant. Occasionally the root apices of the adjacent central incisor and canine are in close proximity. In other cases the ridge thickness could be inadequate and require augmentation. When the orthodontist opens the space, the papilla heights are adversely affected. Some adolescent patients have altered passive eruption after orthodontic treatment, which affects the level of the gingival margins. Finally, questions commonly arise regarding the appropriate age for implant placement in these young patients. If not addressed, these issues could compromise the aesthetics of the implant restoration. This article will use several clinical examples to discuss each of these 6 potential problems and provide guidelines for their solutions.

The combination syndrome: a literature review

Although combination syndrome is recognized by many clinicians, documented observations seem to be rare. The aim of this article was to critically review the literature regarding combination syndrome to evaluate the evidence for this concept. A search of the dental literature with Medline/PubMed through July 2002, focusing on the combination syndrome and related features, was undertaken and combined with a hand search of older references and textbooks on removable prosthodontics.

A multidisciplinary approach to enhance implant esthetics: case report

Esthetic implant-supported restorations in the anterior maxilla present a number of clinical challenges to the dentist, including the need to preserve or restore the periimplant hard and soft tissue architecture around the implant site. In this clinical case report, two implant systems were used to restore two missing maxillary central incisors to make use of the physical properties in each system. Two different surgical protocols were used to place each implant, and the deficient alveolar bone was restored with an autogenous bone graft. After a detailed clinical evaluation, a comprehensive treatment plan was developed to address the unique demands of the patient. Both teeth were fully restored with esthetic, implant-supported, single-tooth restorations, and clinical results were recorded postoperatively.

Bovine-HA spongiosa blocks and immediate implant placement in sinus augmentation procedures. Histopathological and histomorphometric observations on different histological stainings in 10 consecutive patients

Bovine mineral spongiosa block (B-SB) was used as a bone substitute in sinus augmentation procedures in 10 consecutive patients. Implants were placed during the same session. The purpose of this study was to histopathologically examine the healing of the grafted site around the implants at 12 months. Radiographic follow-up showed apparent bone apposition in the augmented area around the implants. Clinically, all 36 implants were stable and integrated with the surrounding tissue. Histopathologically, new bone formation was evident in all specimen hard tissue cores. Hydroxyapatite particles were present in direct contact with the remodeled osseous tissue. Mallory trichrome staining showed different stages of mineralization and maturation of the newly formed bone around the grafted mineral particles. Morphometric evaluation of Picrosirius red stained slides under polarized light microscopy was performed at the peripheral/external and deep section slides of all specimens. The average bone area fraction was 34.2%, with a 1 : 5.4 mean lamellar/woven bone ratio at the peripheral side and 53.0%, with 1 : 2.5 mean ratio at the deep side. The differences of both parameters between the two sites were statistically significant. B-SB proved to be a suitable grafting material with simultaneously placed implants in sinus floor augmentation procedures.

Histopathological morphometric evaluation of 2 different hydroxyapatite-bone derivatives in sinus augmentation procedures: a comparative study in humans

BACKGROUND

Xenografts to augment the maxillary sinus have been used extensively. The aim of the present study was to evaluate, qualitatively and quantitatively, two different HA derivatives of natural and synthetic sources on newly formed bone in the augmented sinus.

METHODS

A bilateral sinus augmentation procedure with simultaneous (16 out of 20 sites) or subsequent implant placement was performed in 10 patients. The antrum was randomly filled with a deproteinized, bovine hydroxyapatite mineral (B-HA) on one side and a non-ceramic resorbable hydroxyapatite (NC-HA) on the other. Cylindrical specimens were harvested from the augmented core at 12 months. Decalcified specimens were sectioned at a cross-horizontal plane and stained with hematoxylin and eosin for histopathologic and histomorphometric examinations. Tissue area fractions of bone, marrow, and the grafted particles were calculated for each specimen from the lateral to the deep region, and changes in values were compared within each material and between them.

RESULTS

New bone formation was evident. B-HA and NC-HA particles were observed in all specimens surrounded by newly formed bone in direct connection or by soft tissue marrow. Morphometrically in the B-HA sites, from the lateral to deeper area, bone area fraction increased from 29.8% to 54.2% (average 42.1%) and marrow area fraction decreased from 37.9% to 26.7% (average 33.3%). The mineral area fraction decreased from 32.3% to 19.1% (average 24.7%). All increasing/decreasing patterns were statistically significant (P < 0.001). In the NC-HA sites, from the lateral to deeper area, bone area fraction increased from 25% to 36.5% (average 32.3%) and marrow area fraction decreased from 51.6% to 41.9% (average 43.2%) (P <0.001). The mineral area fraction decreased from 29% to 21.7% (average 24.6%) (P = 0.038). Comparison between the two HA derivative groups showed a significant difference between the bone area fraction averages (P = 0.0053) and between the increasing patterns along the core depth (P = 0.0006). There was also a significant difference between the decreasing marrow patterns (P = 0.003), but not between their averages. Comparison between the mineral area fractions showed no differences.

CONCLUSIONS

B-HA and NC-HA were proven to be biocompatible materials. Although the B-HA-augmented sites showed a higher percentage of bone formation at 12 months, both are suitable bone derivatives in sinus augmentation procedures and can accommodate osseointegrated implants.

Porous bovine bone mineral in healing of human extraction sockets. Part 1: histomorphometric evaluations at 9 months

BACKGROUND

Extraction socket wound healing is characterized by resorption of the alveolar bone at the extraction site. This produces a decrease in ridge volume, deformations of ridge contours, and, thus, difficulties in delayed placement of root-form implants in an ideal position. Cancellous porous bovine bone mineral (PBBM) applied to fresh extraction sockets has recently been proposed to minimize the reduction in ridge volume. The aim of this study was to investigate the influence of PBBM grafted particles on the histopathologic pattern of the intrasocket regenerated bone and to evaluate histomorphometrically the healed PBBM grafted extraction socket site at 9 months' post-extraction.

METHODS

PBBM particles (250 to 1,000 microns in size) were grafted in 15 fresh human extraction sockets in 15 patients. Socket wall bone height was measured from the crestal ridge level before the mineral particles were inserted. Primary soft tissue closure was performed to protect the grafted particles via a pediculated split palatal flap. At 9 months, socket bone walls were remeasured and cylinder bone samples of the previously PBBM-grafted sites were obtained. Decalcified specimens were sectioned at a cross-horizontal plane and stained with hematoxylin and eosin for histopathologic and histomorphologic examination. Tissue area percentage of bone, PBBM, and connective tissue (CT) was calculated for each specimen from the crestal to the apical region and changes in values compared.

RESULTS

Average clinical overall bone fill of the augmented socket sites was 82.3%. Histologically, PBBM particles were observed in all specimens. Newly formed bone was characterized by abundance of cellular woven-type bone in the coronal area, while lamellar arrangements could be identified only in the more apical region. New osseous tissue adhered to the PBBM. Histomorphometric measurements showed an increase of mean bone tissue area along the histological sections from 15.9% in the coronal part to 63.9% apically (average 46.3%). CT fraction decreased from 52.4% to 9.5% (average 22.9%) from the crestal to the apical region. PBBM area fraction varied from 26.4% to 35.1% (average 30.8%). Statistical analysis of the comparison between areas of bone, CT, and PBBM was performed in different points along the coronal-apical axis. Differences were significant (P <0.01) at the most crestal, middle, and apical section cut areas, but not at the cervical section cuts. Bone area fraction increased in the apical direction as much as CT correlatively decreased. Unlike CT and bone, PBBM retained constant relative volume (approximately 30%), regardless of the depth of the specimen cores.

CONCLUSIONS

PBBM particles are an appropriate biocompatible bone derivative in fresh extraction sockets for ridge preservation. The resorbability of this xenograft could not be recognized in a 9-month period. Further investigation is needed to clarify the resorptive mechanisms of PBBM.

Use of prosthesis-generated computed tomographic information for diagnostic and surgical treatment planning

Diagnosis, treatment planning, and prediction of a final implant-supported prosthetic outcome require precise noninvasive presurgical information. By combining the use of a clinically verified barium-coated template and interactive computed tomography (SIM/Plant, Columbia Scientific, Inc., Columbia, Maryland), the implant team can determine and address the relevant issues affecting treatment outcomes. Those issues include: implant-prosthesis incompatibility, recognition of anatomic limitations and anomalies, the need for presurgical bone augmentation, implant diameter and distribution, abutment type and angle, bone density, soft tissue augmentation requirements, accurate fee determination, and medicolegal protection. The data collection methodology and format for the Mecall and Rosenfeld prosthesis prediction analysis are discussed as part of case presentation.

The effect of prosthodontic treatment on alveolar bone loss: a review of the literature

STATEMENT OF PROBLEM

Complete, fixed partial, removable partial, and implant-supported dentures have been used to comfortably and esthetically replace missing teeth. However, it is not certain what effect these prostheses have on the residual ridge.

PURPOSE

This article compares various prosthetic treatments to restore completely and partially edentulous mouths for their ability to preserve residual alveolar bone.

MATERIAL AND METHODS

A review of the literature was performed to discuss the effects of tooth replacement on residual alveolar bone.

RESULTS

The literature seems to indicate that the presence of a dental prosthesis affects the size and form of the residual alveolar ridge and bone.

CONCLUSION

An implant-supported fixed prosthesis to restore missing teeth in partially or completely edentulous jaws seems to be the best means of preserving residual alveolar bone.

The application of deproteinized bovine bone mineral for ridge preservation prior to implantation. Clinical and histological observations in a case report

Alveolar ridge preservation following tooth extraction is important when implant-supported oral rehabilitation is considered. The ability to maintain the ridge allows implant placement in an ideal position, fulfilling both functional and esthetic demands. A deproteinized bovine bone mineral (DBBM) was used as a socket site filler material to maintain ridge configuration, without applying an occlusive membrane. The material was grafted and packed onto the socket sites immediately after extractions, and subsequently primary soft tissue closure was attempted. The ridge healed for 9 months before the second surgical procedure, in which the implant was placed. New bone formation was observed in all histological specimens. DBBM particles adhered to a highly osteocyte-rich woven and lamellar-type bone. Clinically and histologically, this report demonstrated DBBM particles to be an effective biocompatible filler agent in extraction sockets for ridge preservation prior to titanium fixture implantation. Randomized controlled clinical trials are needed to fully evaluate the usefulness of this material in ridge preservation after tooth extraction.

Current perspectives in residual ridge remodeling and its clinical implications: a review

PURPOSE

This article reviews the current understanding of the biology of tooth extraction wound healing and residual ridge remodeling.

METHODS

The review of the biology of tooth extraction wound healing involves a discussion of the different cells populating the tooth extraction wound, the matrix formation, and the control of the repair process in the short-term. Defects in socket matrix formation or cellular activity will lead to stalled healing. The review of residual ridge remodeling describes the long-term result of tooth extraction and formation of residual ridges, in which the quantity of bone tissue continuously decreases. This may suggest that any potential regulatory factors of residual ridge resorption should have an adverse effect either on the increased catabolic activity by osteoclasts or on the decreased anabolic activity by osteoblasts. Both short-term tooth extraction healing and long-term residual ridge remodeling processes are interdependent. Furthermore, any potential genetic and environmental regulatory factors can affect the quality and quantity of bone by altering the gene expression events taking place in bone cells.

RESULTS

The intent of this article was to review the current progresses of biologic research on residual ridge remodeling and to relate the changes at molecular, cellular, and tissue levels. The understanding of residual ridge remodeling may provide a sound scientific basis for improved restorative and therapeutic treatments of the edentulous population.

The traditional therapeutic paradigm: complete denture therapy

The art and science of complete dentures for oral restoration has been espoused and debated for over a century. A tradition of clinical mentoring has passed this prosthodontic trust through time to create an educational cycle where the pupil ultimately became the tutor for yet another pupil. Today's clinical techniques and judgments are an amalgamation of these original prosthodontic philosophies. This article will bring forward some procedures for the fabrication of complete dentures for the scrutiny of their scientific bases. Scrutiny does not imply that aspects of therapy not proved in studies of rigorous scientific design are untruths. However, it is incumbent that those aspects of denture therapy regarded as "public domain" by the corpus of the profession be analyzed. It is also incumbent that possible costly or harmful aspects of denture therapy be identified. There is a paucity of "procedural research" in clinical investigations; research that involves performing an invasive or clinician-intensive procedure. This article also discusses the difficulties in performing procedural research as a means of understanding its importance, but also realizing the reasons that this type of research is not prevalent in the dental and health professional literature. The most common types of investigations used to evaluate patient acceptance and function of dentures will also be discussed.

Oral status and prosthetic factors related to residual ridge resorption in elderly subjects

Our earlier studies on edentulous elderly subjects have shown associations of severe resorption in the mandibular residual ridge with female gender and systemic diseases. The aim of this study was to examine whether other factors also were related to residual ridge resorption (RRR). Among 177 edentulous elderly subjects effects on RRR were investigated with regard to history of edentulousness and denture-wearing, the condition of the dentures and soft tissues, dental status of the opposing jaw, and oral hygiene habits. No significant association was found between degree of resorption and duration of edentulousness in either the mandible or the maxilla. RRR was related to denture quality (P < 0.05); however, severe resorption was not. In the maxilla previous use of removable partial dentures was a factor contributing to the resorption (odds ratio (OR), 2.4); flabby ridge was related to the severity of the resorption (OR, 2.4). This study showed local factors related to RRR more often in the maxilla than in the mandible, thus suggesting that severe resorption in the mandible is influenced more by systemic factors than by those investigated in this study.

Issues related to single-tooth implants

Many practitioners place single-tooth implants when the teeth adjacent to the edentulous space are intact, free of caries and have had no restorations, and the patient is reluctant to wear a removable appliance for physical or psychological reasons, or both. The main exclusionary factors for a single-tooth dental implant are insufficient bone quantity, poor bone quality and insufficient vertical interarch space to accommodate the prosthodontic components of the implant.

A bone regenerative approach to alveolar ridge maintenance following tooth extraction. Report of 10 cases

TEN PATIENTS WHO REQUIRED two or more anterior teeth extractions were utilized in this study. Extraction procedures were carried out with a full thickness surgical flap approach. After flap reflection, teeth were removed with a minimum of trauma to the surrounding bone. Following extraction silicone-based impression techniques were used to produce a model of the alveolar process and small metal pins were placed in the alveolus to be used as fixed points to make measurements of ridge dimensions. One socket was covered with an expanded polytetrafluoroethylene (ePTFE) barrier membrane (experimental site); the other socket was a conventional control. The soft tissue flaps were then mobilized using periosteal releasing incision and the wound closed with ePTFE mattress sutures. Six months following extraction, patients were treated with flap surgery to expose both extractions sites to remove the ePTFE membranes and to measure ridge dimensions using the pins as fixed points. Clinical and model measurements have shown statistically significant better ridge dimensions at experimental sites than at control (P < or = 0.05). Three patients with exposed membranes had similar dimensional changes as controls. Results from this study suggested that this improved technique offers a predictable alveolar ridge maintenance enhancing the bone quality for dental implant procedures and esthetic restorative dentistry.

Interdisciplinary management of single-tooth implants

Orthodontists treat many patients who are missing maxillary lateral incisors and/or mandibular second premolars. In the past, if the canines could not be substituted for lateral incisors, conventional full-coverage bridges were the common restoration. Recently, resin-bonded Maryland bridges became a popular substitute for conventional bridges to avoid crowns on the nonrestored abutments. However, resin-bonded bridges have a poor long-term prognosis for retention, lasting on average about 10 years. Since implants were introduced into dentistry by Swedish researchers in the mid-1980s, they have become a promising substitute for conventional or resin-bonded bridges. However, to successfully place and restore single-tooth implants in young orthodontic patients several questions must be answered. This article will discuss the many interdisciplinary issues that are involved in placing and restoring single-tooth implants in orthodontic patients.

Guidelines for managing the orthodontic-restorative patient

Occasionally, patients require restorative treatment during or after orthodontic therapy. Patients with worn or abraded teeth, peg-shaped lateral incisors, fractured teeth, multiple edentulous spaces, or other restorative needs may require tooth positioning that is slightly different from a nonrestored, nonabraded, completely dentulous adolescent. Generally, orthodontists are not accustomed to dealing with patients who require restorative intervention. Should the objectives of orthodontic treatment differ for the restorative patient compared with the nonrestorative patient? How should the teeth be positioned during orthodontic therapy to facilitate specific restorations? Should teeth be restored before, during, or perhaps after orthodontics? The answers to these and other important questions are vital to the successful treatment of some orthodontic patients. This article will provide a series of eight guidelines to help the interdisciplinary team manage treatment for the orthodontic-restorative patient.

Factors connected with alveolar bone resorption among institutionalized elderly people

In this socio-dental investigation among 175 institutionalized somatically disabled edentulous elderly people correlations are described between the test subjects' degree of alveolar bone resorption, their gender and age, their duration of edentulousness, and the number of complete dentures worn. All test subjects were interviewed by dental students and clinically examined by dentists. The mandibular alveolar bone resorption was significantly stronger in women than in men and stronger in people who had been edentulous longer. The longer the test subjects had been edentulous and the greater their degree of mandibular alveolar bone resorption was, the more mandibular dentures they had worn. This study among institutionalized elderly people provides for the most part the same results as a previously presented study among much younger people. Obviously, in these respects there are no differences between these groups.

A comparative study of two methods for the orientation of the occlusal plane and the determination of the vertical dimension of occlusion in edentulous patients

The aim of this study was to compare two methods used to orientate the occlusal plane (OP) and to determine the vertical dimension of occlusion (VDO). In method A the VDO was established by means of the rest position, the minimal speaking distance, and the patient's profile. Method B used a newly developed registration pin assembly. The VDO was registered using a silicone occlusion rim and the swallowing technique. The results were compared to the values of the new dentures. Three standardized lateral radiographs were taken at the VDO obtained with methods A, B, and at that of the final dentures. On each radiograph the orientation of the OP to the Camper plane and the VDO were measured by two investigators independently. The results indicated no statistically significant differences between the mean VDO with method A and B compared with the new dentures (P greater than 0.05). With both methods it was not possible to orientate the OP parallel to the Camper plane. None of the occlusal planes of the new dentures were parallel either. Their OP diverged on average by 7 degrees dorso-caudally. The time spent with method B to orient the OP and to determine the VDO was significantly lower than with method A (17-50 min).

An analysis of the effect of mandibular length on residual ridge loss in the edentulous patient

The relationship of mandibular length to residual ridge loss was studied in 22 edentulous patients. Tracings made from cephalometric films taken at initial insertion of complete dentures and at 20 years after placement were measured. Mandibular length was determined to have no statistical relationship to the reduction in residual ridge height in either the maxillae or the mandible. In addition, alveolar bone loss in the one jaw had no relationship to the amount of loss in the other jaw.

Some factors connected with alveolar bone resorption

In this study correlations are described between alveolar bone resorption, patient's age, duration of edentulousness, the number of dentures which have been worn, and dentures being worn day and night. The sample of patients for this study consisted of 92 edentulous persons treated with complete dentures at a dental school clinic. The test subjects were asked to fill in a questionnaire to obtain data regarding the research factors. A method for the classification of alveolar bone resorption was developed and the test subjects were divided into classes for alveolar bone resorption according to this method. All data were processed by means of a computer program. The longer the test subjects had been edentulous and the more dentures they had worn, the more intensive was the alveolar bone resorption, particularly in the lower jaw. No significant correlation was found between alveolar bone resorption and dentures being worn day and night.

Bone resorption around fixtures in edentulous patients treated with mandibular fixed tissue-integrated prostheses

Bone loss around osseointegrated titanium fixtures supporting mandibular fixed prostheses has been measured by means of stereoscopic intraoral radiography. Forty-six patients treated with the osseointegration implant method according to Brånemark have been followed for an observation period of up to 6 years. The bone loss was small, approximately 0.5 mm during the first postsurgical year and thereafter 0.06 to 0.08 mm annually. Poor oral hygiene and clenching of teeth significantly influenced bone loss. More bone was lost around the medial fixtures than around the more posterior ones.

Resorption of residual ridges (RRR) in rats

The post-extraction resorption of residual ridges (RRR) is a major and largely unsolved health problem, probably of multifactorial etiology. In order for one to study the role of specific factors in the pathophysiology of RRR, the use of animal models is desirable. The purpose of this study was to establish a reliable animal model and a standardized assay system to measure RRR for future experiments. A new oblique cephalometric device was designed to take pairs of xeroradiographs on the right and left sides of the rat skull and mandible at a 45-degree angle to the horizontal plane. Preliminary studies confirmed the reproducibility of the technique. All molars were extracted with minimal trauma from the right maxilla and mandible in five male Sprague-Dawley rats (40 days old). Longitudinal cephalographic examinations were performed before and immediately after extraction and at two, four, eight, and 12 weeks after extraction. Alveolar bone resorption was measured on enlarged cephalographs (5.7 X) at a point mesial to the mandibular first molar. Sequential mean bone resorption was 0.8 +/- 0.2 mm (S.D.), 1.0 +/- 0.3, 1.3 +/- 0.3, and 1.5 +/- 0.4, respectively. Graphically, these findings produced bone loss curves similar to those observed in man. These results indicate that the rat model may be utilized in longitudinal studies of the resorption of the residual ridge.

Clinical long-term study of complete denture wearers

Thirty-two patients initially treated with a complete denture in the maxilla or mandible were examined after 21 years. The examination included a questionnaire plus clinical and radiographic examinations. Denture function was assessed in general as very good or fairly good by the patients, but about half of the subjects also felt that the dentures needed some attention. The patients generally had a high evaluation of their chewing ability. The functional state of the masticatory system, both according to patients' reports and the clinical signs, was generally good compared with previously published epidemiologic studies. The denture quality and tissue health were far from optimum according to prosthodontic criteria. By overall judgment, 14 patients needed new dentures and six needed relining, occlusal adjustment, or repair. Tracing of cephalometric radiographs showed wide variations in bone resorption among patients.

Augmentation of the atrophic maxilla with interpositional autogenous bone grafts

Extreme ridge atrophy is a significant problem when it occurs in the maxilla, since inadequate denture function, as well as poor facial aesthetics, commonly result. Use of the Le Fort I osteotomy of the maxilla with interpositional iliac cortico-cancellous bone grafts is a predictable method of ridge augmentation in severe cases. In our experience, secondary vestibuloplasty has not been necessary prior to construction of new prostheses. Patient satisfaction has been excellent.

Continuing changes in the contour of the maxillary residual alveolar ridge

Using a cast measuring technique, the change in contour of the residual maxillary alveolar ridge of patients who have worn dentures for a number of years and are then fitted with new dentures, has been investigated. The study confirmed that even after 30 years of denture wearing, further bone resorption may occur beneath new dentures.

The maxillary complete denture opposing the mandibular bilateral distal-extension partial denture: treatment considerations

The dentist should approach the treatment of the complete maxillary denture opposing the mandibular bilateral distal extension partial denture cautiously, and the institution of correct treatment initiatives is essential. Every patient must be aware from the outset that the longest possible life of any prosthesis with the least possible harm to the remaining tissues can only be ensured by regular recall and maintenance care.

Surgical-prosthetic correction of dentofacial deformities

The rehabilitation of optimal masticatory function in many persons who have difficult prosthetic dental conditions can be significantly aided by newer orthognathic surgical procedures. The combined surgical-prosthetic approach for these patients requires close cooperation and communication between the general dentist or prosthodontist and the oral surgeon, particularly because various aspects of the surgical treatment planning for these patients differ greatly from those for patients with complete natural dentitions. A discussion and report of cases illustrate germane aspects of evaluation of conditions, treatment planning, and surgical approaches to the more commonly encountered surgical-prosthetic dental problems.

The significance of age changes in human alveolar mucosa and bone

The denture-bearing mucosa of aged maxillary and mandibular ridges show morphologic changes that are irreversible. These changes limit the extensibility and the rebound capacity of the denture-bearing area.

Five-year cephalometric study of mandibular ridge resorption with different posterior occlusal forms. Part I. Denture construction and initial comparison

The average 5 year reduction of the occluding vertical dimension (nasion to menton) for 45 patients was 3.2mm. (2.8 mm. for the anatomic group, 3.2 mm. for the semianatomic group, and 3.6 mm. for the nonanatomic group, each constituting 15 patients). Mandibular physiologic resting face height became foreshortened on the average only one third as much as the morphologic centric occlusion face height. Tabulation of adjustments for sore spots indicated that: the fewest postinsertion appointments were required for the anatomic group of patients; three fourths of 604 denture base alterations were on lower dentures; for upper and lower denture base alterations, one third were made on the borders and two thirds, on the basal seat; one sixth of all alterations were made at routine recall examinations; the fewest upper denture base alterations were for the nonanatomic patients; and the fewest adjustments of the lower denture base on the tissue surface and on the borders were done for the anatomic group of patients. This investigation has been underway for 18 years, and several more re

Comparing ridge resorption with various surgical techniques in immediate dentures

The three surgical techniques of simple tooth extraction and labial plate and intraseptal alveoloplasty were compared. The results were confirmed by statistical analysis. The conclusion of this study clearly indicated that simple tooth extraction is the best surgical approach to be followed to preserve as much of the residual alveolar ridge as possible.