Relationship between crevicular aspartate aminotransferase levels and periodontal disease progression.

BACKGROUND: Aspartate aminotransferase (AST), an enzyme released from necrotic cells, has been identified in gingival crevicular fluid (GCF), and elevated levels are associated with periodontal tissue destruction. The aim of this study was to examine the relationship between elevated GCF levels of AST and periodontal disease progression. METHODS: Over a 12-month period, 8 to 10 interproximal sites in 41 periodontitis subjects (PS) and 15 healthy subjects (HS) were monitored. Clinical measurements included relative attachment level (RAL), probing depth, and bleeding on probing (BOP). Semiquantitative levels of GCF AST (< 800 microIU, > or = 800 microIU, and > or = 1,200 microIU) were determined using a chairside assay. At the 6- and 12-month visits, scaling and root planing and prophylaxis were performed in the PS and HS, respectively. Sensitivity, specificity, positive predictive values (PPV), and negative predictive values (NPV) were calculated for 2 diagnostic criteria (AST > or = 800 microIU, AST > or = 1,200 microIU) utilizing 4 thresholds of disease progression as determined by 2 methods (absolute change in relative attachment level and cumulative sum [CUSUM]). RESULTS: The percentage of sites exhibiting AST > or = 800 microIU, AST > or = 1,200 microIU, and BOP in the PS was significantly (P<0.02) lower at 6 and 12 months compared to baseline. The use of crevicular AST activity to monitor periodontal disease progression was associated with many false-positive results. Overall, low specificities, PPV, and odds ratios were demonstrated by the assay when using 2 diagnostic criteria and 4 thresholds of disease progression. The high NPV suggest that a negative AST test result was indicative of a periodontally stable site. CONCLUSIONS: These results demonstrate that elevated levels of AST were present at sites that did not subsequently exhibit disease progression. The high prevalence of AST-positive sites due to gingival inflammation diminished the test's ability to discriminate between progressive and stable, but inflamed, sites.

Effect on bone healing of bone morphogenetic protein placed in combination with endosseous implants: a pilot study in beagle dogs.

Although dental implants have become an effective treatment modality for the replacement of missing teeth, their predictability relies on successful osseointegration during the healing period. The purpose of this pilot study was to evaluate the effect of recombinant human bone morphogenetic protein-2 (rhBMP-2) on early bone formation within the perforations of dental implants in beagle dogs. Histologic sections were evaluated for the extent of new bone formation within a 1-mm diameter of through-and-through perforations. Data indicated that significantly more bone formation occurred with rhBMP-2-treated sites within the implant perforation (P < 0.01) compared to sites treated with the vehicle alone. This pilot study indicates that rhBMP-2 increases the rate and extent of bone formation in combination with dental implants.

Treatment of periodontitis by local administration of minocycline microspheres: a controlled trial.

BACKGROUND: Periodontitis is an inflammatory condition of tooth-supporting tissues that is usually treated by mechanical removal of plaque and microorganisms that adhere to teeth. This treatment, known as scaling and root planing, is not optimally effective. Adjunctive therapy with locally delivered antimicrobials has resulted in improved clinical outcomes such as probing depth reduction. This article reports on the efficacy and safety of locally administered microencapsulated minocycline. METHODS: Seven hundred forty-eight (748) patients with moderate to advanced periodontitis were enrolled in a multi-center trial and randomized to 1 of 3 treatment arms: 1) scaling and root planing (SRP) alone; 2) SRP plus vehicle; or 3) SRP plus minocycline microspheres. The primary outcome measure was probing depth reduction at 9 months. Clinical assessments were performed at baseline and 1, 3, 6, and 9 months. RESULTS: Minocycline microspheres plus scaling and root planing provided substantially more probing depth reduction than either SRP alone or SRP plus vehicle. The difference reached statistical significance after the first month and was maintained throughout the trial. The improved outcome was observed to be independent of patients' smoking status, age, gender, or baseline disease level. There was no difference in the incidence of adverse effects among treatment groups. CONCLUSIONS: Scaling and root planing plus minocycline microspheres is more effective than scaling and root planing alone in reducing probing depths in periodontitis patients.

Evaluation of recombinant human bone morphogenetic protein-2 in oral applications including the use of endosseous implants: 3-year results of a pilot study in humans.

BACKGROUND: This study evaluated patients who had been treated with recombinant human bone morphogenetic protein-2 (rhBMP-2) loaded in an absorbable collagen sponge (ACS) in human extraction sites or in sites that required alveolar ridge augmentation. An earlier report on the same patients revealed that after 4 months, implantation of rhBMP-2/ACS was safe, as determined by clinical, radiographic, systemic, and immunological analyses. In this longer-term follow-up, eligible patients were restored with endosseous dental implants in the area treated with rhBMP-2/ACS and bone biopsy samples were taken for histological analysis of the treated human bone tissue. The primary objective was to monitor the long-term safety of patients treated with rhBMP-2/ACS. Another objective was to evaluate the dental implants placed in the sites treated with rhBMP-2. METHODS: Patient safety was evaluated by clinical examinations, periapical radiographs, and occurrence of adverse experiences. Dental implants were evaluated by radiographic and clinical examination. All 12 patients have been followed for 3 years. RESULTS: Two years following surgical implantation of rhBMP-2/ACS, no serious or unexpected adverse experiences occurred. The adverse experiences that did occur were mostly benign and compatible with the dental implant surgeries performed in these patients. No adverse experiences were deemed as related to the rhBMP-2/ACS. Furthermore, no safety concerns in the local area of rhBMP-2/ACS placement were noted, based on oral wound examinations. In the 10 patients (6 extraction socket patients and 4 augmentation patients) who received endosseous implants, all implants were clinically stable at all assessments and all 10 patients have been functionally restored. Histological evaluation of the human bone core biopsies revealed normal bone tissue formation identical to the surrounding native bone. Three-year follow-up clinical examinations revealed that all implants had stable marginal bone levels and healthy peri-implant tissues. CONCLUSIONS: These 3-year results demonstrate that rhBMP-2/ACS can be used safely in human patients. Human bone biopsies reveal normal bone formation in areas treated with rhBMP-2/ACS. Endosseous implants placed in these areas were all stable with no radiographic or clinical complications. The results from this study suggest that rhBMP-2/ACS (0.43 mg/ml) can be safely used in tooth extraction sites and in local ridge augmentation procedures and that endosseous dental implants placed in bony areas treated with rhBMP-2/ACS are stable and can be functionally restored without complication.

Correlation of peri-implant health and aspartate aminotransferase levels: a cross-sectional clinical study.

At present, there are no diagnostic tools that permit early detection of peri-implantitis. The purpose of this cross-sectional study was to evaluate the correlation of aspartate aminotransferase (AST) levels with traditional periodontal clinical parameters around dental implants, since AST has been associated with destruction of cardiac, hepatic, and periodontal tissues. Twenty healthy volunteers with 59 implants were recruited from the Harvard School of Dental Medicine clinics. Clinical parameters evaluated included: AST level, probing depth (mm), Gingival Index (0, 1, 2, or 3), and bleeding on probing (0 or 1). Utilizing the site or implant as the unit of measure, the authors found a statistically significant association of increased AST activity with positive bleeding on probing, increased probing depth, and increased Gingival Index. No statistical correlations were found between clinical indices and increased AST levels when the results were examined on an individual patient basis. This cross-sectional study was able to demonstrate a statistical correlation between diseased clinical periodontal parameters and elevated AST levels.

The effect of interleukin-11 on the progression of ligature-induced periodontal disease in the beagle dog.

BACKGROUND: The rate of progression of periodontal disease is dependent on the complex regulatory interactions between bacteria and the immune modulators of the host response. The purpose of this investigation was to determine if recombinant human interleukin-11 (rhIL-11), known to downregulate several inflammatory modulators, has the ability in subcutaneous administration to reduce the rate and/or extent of periodontal attachment loss and radiographic bone loss in a ligature-induced periodontal disease beagle dog model. METHODS: Twenty 18-month-old female beagle dogs were brought to optimal periodontal health over a 2-week period. Periodontal disease was induced by placing 2.0 silk ligatures around the mandibular first molar and premolar teeth. The dogs were divided into 3 treatment groups and one control group. The 3 treatment groups received subcutaneous injections of either 15, 30, or 80 microg/kg of rhIL-11 in saline buffer twice a week. The placebo group received buffer only subcutaneously twice a week. The gingival health of each animal was measured by recording the presence or absence of gingival inflammation, plaque, and bleeding upon probing. Attachment levels and bone height were also measured. Treatment administration and clinical and radiographic evaluations were performed in a masked fashion. RESULTS: At week 8, the placebo group had 3.89 mm of attachment loss and 73.8% radiographic bone remaining. The 15 microg/kg group had 1.99 mm attachment loss and 89.5% bone remaining; the 30 microg/kg group had 0.84 mm attachment loss and 92.5% bone remaining; and the 80 microg/kg group had 1.05 mm attachment loss and 85.5% bone remaining. All 3 treatment groups lost significantly less attachment and retained significantly more bone than did the placebo group. CONCLUSIONS: The study indicates that subcutaneous injections of rhIL-11 were able to slow the progression of attachment and radiographic alveolar bone loss in a ligature-induced beagle dog model.

Benchmarking the dental implant evidence on MEDLINE.

The purpose of this study was to estimate the quantity of dental implant literature available on MEDLINE for evidence-based clinical decision-making and to identify its location. A search strategy based on Medical Subject Headings for dental implants was developed to examine MEDLINE using the Ovid Web Gateway search engine. Sensitive and specific methodologic search filters identified 4 categories of information: etiology, diagnosis, therapy, and prognosis. The results were then subdivided by year to identify trends and sorted to identify the sources of publications. The searches identified 4,655 articles published in English between 1989 and 1999 on human dental implants on MEDLINE. The mean number of articles (+/- SD) per year ranged from 15 +/- 11 for specific searches to 107 +/- 50 for sensitive searches. The number of articles increased by 14% to 43% each year for the sensitive search. When subdivided by clinical category, the mean numbers of articles per year for sensitive and specific searches were, respectively: diagnosis 12 +/- 7.5 and 1.5 +/- 1.6, etiology 58 +/- 33 and 1.9 +/- 2.5, therapy 23 +/- 15 and 0.3 +/- 0.5, and prognosis 67 +/- 33 and 12 +/- 8.3. Four dental journals account for approximately half of these publications. These results provide 6 key central findings: (1) there appears to be a substantial literature of clinically relevant information on implants upon which to base clinical decisions; (2) the implant literature is significantly biased toward articles addressing prognosis; (3) to stay current, one would need to read between 1 and 2 articles per week 52 weeks per year, and this number increases significantly each year; (4) approximately 50% of the articles were published in 4 journals, whereas the remainder reside in approximately 97 other journals, making it difficult to stay current; (5) these trends reaffirm the need for lifelong learning; (6) these trends also suggest the need for computer-based clinical knowledge systems.

A 5-year prospective clinical and radiographic study of non-submerged dental implants.

Osseointegrated implants as anchors for various prosthetic reconstructions have become a predictable treatment alternative. It was expected that implants required submucosal placement during the healing period for successful tissue integration. However, it has been demonstrated that healing and long-term health of implants could be achieved with equal predictability in a 1-stage, non-submerged approach. This prospective 5-year study not only calculates implant success by life table analysis, but also evaluates the correlation between observed bone level changes with clinical parameters as measured by suppuration, plaque indices, bleeding indices, probing depth, attachment level and mobility. A total of 112 ITI dental implants were inserted in different areas of the jaws. Clinical and radiographic parameters were evaluated annually for 5 years, whereas a portion of the study group for which 6-year evaluations were available were included in the life-table analysis. The overall success rate after 5 years in service was 99.1%, while after 6 years it was reduced to 95.5% due to the fracture of 3 implants in 1 patient. The mean crestal bone loss experienced during the first year was 0.6 mm followed by an annual yearly loss of approximately 0.05 mm. No significant differences could be found between the amount of bone loss measured at each of the yearly follow-up visits. This suggests that statistically the followed implants did not show any radiographically measurable bone loss following the initial period of bone loss associated with implant placement and osseointegration. Low levels of correlation between the individual and cumulative clinical parameters with radiographically measured bone loss suggests that these parameters are of limited clinical value in assessing and predicting future peri-implant bone loss.

A retrospective study of dental implants in diabetic patients.

The efficacious placement of dental implants in diabetic patients remains controversial. Definitive guidelines with objective criteria, including the type of diabetes, age of onset, and level of long-term control, have not been determined. In addition, few relevant literature citations assess the survival rate of implants in diabetic patients. Therefore, it is the purpose of this study to assess the success and survival rates of dental implants in diabetic patients. In this retrospective analysis, 215 implants placed in 40 patients at 2 clinical centers were evaluated. Chart reviews and interviews provided medical and implant data. From the analysis, 31 failures occurred, for an overall success rate of 85.6%. Of these failures, 24 occurred within the first year of functional loading. The mean time of functional load was 4.05 +/- 2.6 years. When the success rate was analyzed by implant location, success rates for the maxilla and mandible were 85.5% and 85.7%, respectively. For the anterior and posterior regions, success rates were 83.5% and 85.6%, respectively. The lifetable analysis revealed a cumulative success rate of 85.7% after 6.5 years of function. Based on the data, the survival rate of dental implants in controlled diabetic patients is lower than that documented for the general population, but there is still a reasonable success rate. The increase in failure rate occurs during the first year following prosthetic loading.

Human histologic evaluation of bioactive ceramic in the treatment of periodontal osseous defects.

This study examined the healing of intrabony defects around 5 teeth treated with bioactive glass ceramic (PerioGlas). Healing was evaluated by clinical measurements, radiographic observation, and histologic analysis. The protocol included a presurgical phase of scaling and root planing therapy, with measurements obtained immediately prior to the surgical procedures and after 6 months of healing. Following therapy there was a mean of 2.7 mm of probing depth reduction, 2.2 mm of clinical attachment gain, and 0.5 mm of recession. The histologic analysis revealed healing by a long junctional epithelium with minimal new connective tissue attachment to the teeth, except in one case where the intrabony region demonstrated new cementum formation and new connective tissue attachment. Graft particles were found to be biocompatible, as evidenced by being embedded in a stroma of dense connective tissue with minimal inflammatory infiltrate. There was minimal new bone formation limited to the most apical borders of the defects. No signs of periodontal regeneration as defined by new cementum, periodontal ligament, and bone formation on a previously diseased root surface were observed. Although the clinical results are encouraging and radiographs evidenced radiopacities within the defects, histologic analysis revealed that as a periodontal grafting material, bioactive glass ceramic has only limited regenerative properties.

The effect of insulin therapy on osseointegration in a diabetic rat model.

As patients become edentulous, dental implants have been one treatment alternative. Although studies indicate that dental implants inserted in healthy patients have been successful, their placement in the diabetic patient remains controversial. The purpose of this study utilizing histometric parameters compares the course of osseous healing around endosseous implants in normal non-diabetic and insulin controlled diabetic rats. Diabetes was induced by a single intraperitoneal injection of streptozotocin. Blood glucose was monitored by the glucose-oxidase method and controlled with daily insulin injections. Sterile custom fabricated commercially pure solid cylinder titanium implants, with a titanium plasma-sprayed surface were placed in the femora of each animal. The results indicate that insulin therapy was able to upregulate the formation of bone around implants inserted in the streptozotocin-induced diabetic rat model. However, histometric parameters utilized indicated that although the total quantity of bone formation was greater in the insulin controlled group, there was significantly less bone-to-implant contact in the insulin controlled diabetic group as compared to normal non-diabetic controls.

A radiographic evaluation of bone healing around submerged and non-submerged dental implants in beagle dogs.

BACKGROUND: The rehabilitation of the oral cavity with dental implants has become a predictable treatment modality. However, there have been only a few direct comparisons evaluating the submerged and nonsubmerged placement techniques. The purpose of this study was to characterize radiographic peri-implant bone changes following the insertion of submerged and nonsubmerged implants in the beagle dog. METHODS: At the end of the extraction healing phase, 19 submerged and 19 nonsubmerged implants were randomly placed in a split-mouth study design and observed over an 18-week period. For submerged implants, a second stage surgery and transmucosal abutment attachment was performed at week 12. Standardized dental radiographs taken at baseline, week 12, and week 18 were used to measure peri-implant bone changes. The radiographs were analyzed with a simple computer assisted method. RESULTS: A total of 43 standardized radiographs were exposed to evaluate the 38 implants. During the study period, all submerged and nonsubmerged implants demonstrated peri-implant bone loss. At baseline, both submerged and nonsubmerged implants had similar bone levels (P > or = 0.05). When the mean peri-implant bone levels for submerged and nonsubmerged implants were compared from baseline to week 12, nonsubmerged implants had a significantly greater amount and rate of bone resorption than submerged implants (P < or = 0.05). Following week 12, the initially submerged implant had a significantly higher rate and amount of peri-implant bone loss than the nonsubmerged implants (P < or = 0.05). However, by the end of the study period, week 18, both submerged and nonsubmerged implants had comparable bone levels (P > or = 0.05). CONCLUSIONS: The study indicates that, although the temporal patterns of peri-implant bone resorption differed, there were no differences between submerged and nonsubmerged implants in the overall amount and rate of peri-implant bone loss.

Wound healing around endosseous implants in experimental diabetes.

Wound healing has been shown to be altered in diabetes mellitus. The aim of this study was to identify the effects of streptozotocin-induced diabetes on osseointegration. Diabetes was induced in 40-day-old rats by intraperitoneal injection of 70 mg per kg streptozotocin. At 14 days postinjection, implants were placed in the femora of 10 diabetic and 10 age-matched normal rats. Animals were sacrificed at 28 and 56 days following implantation. Histometric results indicated that the quantity of bone formation was similar for diabetic and control animals (P > .05). However, less bone-implant contact was observed for diabetic compared to control animals at both 28 and 56 days (P < .0001). This study demonstrates that the process of osseointegration is affected by streptozotocin-induced diabetes.

The effect of different diagnostic thresholds on incidence of disease progression.

Detection of periodontal disease progression occurs when a predetermined threshold of attachment loss is exceeded during longitudinal monitoring. The incidence of disease progression in a population may be dependent on the method and threshold utilized to identify significant changes in attachment level measurements. The aim of this study was to investigate the effect of utilizing different methods and thresholds on the incidence of disease progression in an untreated periodontitis population. The relationship between baseline clinical parameters and disease progression was also examined. A total of 411 interproximal sites in 46 individuals were monitored monthly over a 6-month period. Disease progression was determined by the cumulative sum (CUSUM) method and by the absolute change in relative attachment level between months 0 and 6 utilizing 3 different thresholds for attachment level change (0.58 mm, 1.16 mm, and 1.74 mm) based upon examiner repeatability using an automated probe. Utilizing the CUSUM method, 49 of 411 sites (11.9%) demonstrated attachment loss over the 6-month observation period. When attachment level changes > or = 0.58 mm, > or = 1.16 mm, and > or = 1.74 mm were used to identify disease progression, the percentage of sites exhibiting deterioration were 19.5%, 8.8%, and 2.9%, respectively. These results demonstrate that the apparent incidence of disease progression was dependent on the method and threshold utilized to detect progressive sites. When utilizing the CUSUM and 0.58 mm thresholds a significant (P < 0.05), but weak relationship (r = -0.26) was observed between baseline relative attachment level measurements and sites exhibiting disease progression. This finding suggests that sites with significant but relatively less attachment loss may be more likely to experience further breakdown compared to sites with a history of greater periodontal destruction.

Guided bone regeneration utilizing expanded polytetrafluoroethylene membranes in combination with submerged and nonsubmerged dental implants in beagle dogs.

Treatment of partial and total edentulism with submerged and nonsubmerged dental implants which follows the concept of osseointegration has become an accepted treatment modality. With compromised implant sites, practitioners have begun to combine one-stage implants with established techniques including guided bone regeneration. However, the clinical evaluation of this technique is limited. Therefore, the purpose of this study was to evaluate osseointegration and bone regeneration around nonsubmerged or submerged implants placed directly into surgically created osseous defects with or without expanded polytetrafluoroethylene (ePTFE) membranes. A total of 24 implants were placed in the mandibles of 4 beagle dogs and randomly assigned to 1 of 3 treatment groups. In group A, nonsubmerged implants were placed into osseous defects and treated with a poncho style ePTFE membrane. These membranes had a hole punched into the center and were slipped over the nonsubmerged implants. In group B, nonsubmerged implants were placed into osseous defects without an ePTFE membrane. In group C, submerged implants were placed into osseous defects and covered with an ePTFE membrane. Histometric measurements of each treatment group were made to determine percent bone gain or loss along the implant surface. Although a number of membrane removals occurred during the healing period, histological analysis indicated osseous ingrowth and osseointegration around nonsubmerged and submerged implants. An overall comparison of the treatment groups with ANOVA revealed that there were no significant differences between treatment groups, P > or = 0.05. However, when the data were stratified into sites which retained or lost the ePTFE membrane, the percent of bone regeneration was reduced in group A. Therefore, it may be recommended that nonsubmerged implants be placed with a submerged or "semi-submerged" protocol when utilized in conjunction with ePTFE membranes.

C-telopeptide pyridinoline cross-links (ICTP) and periodontal pathogens associated with endosseous oral implants.

Detection of periodontal or peri-implant sites exhibiting progressing disease or those at risk of deterioration has proven difficult. Pyridinoline cross-linked carboxyterminal telopeptide of type I collagen (ICTP), a marker specific for bone degradation found in gingival crevicular fluid (GCF), has been associated with both bone and attachment loss in periodontitis and may be useful for predicting disease activity. The aim of this cross-sectional study was to examine the relationship between ICTP levels and subgingival species around implants and teeth from 20 partially and 2 fully edentulous patients. GCF and plaque samples were collected from the mesiobuccal site of each implant and tooth. Radioimmunoassay techniques were utilized to determine GCF ICTP levels. Plaque samples were analyzed utilizing checkerboard DNA-DNA hybridization. Traditional clinical parameters were assessed. Seventy-one implants and 370 teeth from 22 subjects were examined. ICTP levels and subgingival plaque composition were not significantly different between implants and teeth. Implant sites colonized by Prevotella intermedia, Capnocytophaga gingivalis, Fusobacterium nucleatum ss vincentii, and Streptococcus gordonii exhibited odds ratios of 12.4, 9.3, 8.1, and 6.7, respectively of detecting ICTP. These results suggest a relationship between elevated ICTP levels at implant sites and some species associated with disease progression. Longitudinal studies are necessary to determine whether elevated ICTP levels may predict the development of peri-implant bone loss.

Enantiospecific inhibition of ligature-induced periodontitis in beagles with topical (S)-ketoprofen.

Systemic and topical administration of non-steroidal anti-inflammatory drugs (NSAIDs) has been shown to reduce periodontal disease progression in both animal models and human subjects. Our present research focuses on single enantiomers of these agents to examine whether enantiospecific therapy will be efficacious in slowing periodontitis. The purpose of this study was to evaluate the inhibitory effects of (S)-ketoprofen on experimentally induced alveolar bone loss in beagle dogs. 16, 18-month-old, female beagles were brought to optimal periodontal health over a 2-week pretreatment period. Experimental periodontitis was then induced by placing silk ligatures around premolar and molar teeth and by instituting a soft, plaque-promoting diet. At baseline, animals were randomized to 1 of 4 groups, consisting of 2x daily administration of (1) placebo dentifrice, (2) 0.3% (S)-ketoprofen dentifrice, (3) 3.0% (S)-ketoprofen dentifrice, or (4) 10.0 mg (S)-ketoprofen capsules (p.o.) over a 60 day treatment period. Standardized, periapical radiographs exposed at days 1 and 60 were analyzed by computer-assisted digital radiography in order to assess the rate of alveolar bone loss. Secondary outcomes included technetium 99m-tin-diphosphonate (99mTc-Sn-MDP) uptake and the gingival index. At baseline, no differences were observed among the groups for linear bone height or 99mTc-Sn-MDP uptake ratios. From days 1 to 60, cohorts differed significantly in terms of bone loss rates (p < 0.001). In particular, beagles treated with systemic or topical (S)-ketoprofen (0.3% or 3.0% dentifrices) exhibited significantly lower mean rates of bone loss compared to placebo treated beagles (p < 0.05). Group differences in mean radiopharmaceutical uptake ratio changes approached significance (ANOVA, p = 0.07), where animals treated with topical 0.3% (S)-ketoprofen demonstrated a reduction and other groups demonstrated elevations over the 60-day dosing period. Treatment cohorts did differ significantly with respect to changes in mean gingival indices (p < 0.05). Animals treated with 0.3% or 3.0% (S)-ketoprofen dentifrice exhibited significantly reduced elevations in gingival index scores as compared to placebo treated animals. These data provide evidence that enantiospecific therapy with (S)-ketoprofen, topically or systemically delivered, may alter the progression of periodontal disease in the beagle dog model.

The use of replicate resin models in the treatment of maxillary sinus augmentation patients.

The elevation of the floor of the maxillary sinus is becoming a routine surgical procedure to develop the site for dental implants. This delicate procedure is best performed with diagnostics of the highest magnitude. To this point, computer tomographic scans provide valuable information, especially when defining the location and extension of septae transversing the sinus. Additional useful information is provided by a replicate resin model that is constructed from a magneto-optical disk compatible with a personal computer. The image data is then converted to a DOS format. Bone structures of interest are thresholded in each slice based on single-pixel gray levels. Object profiles with linear interpolation and their elaboration generate the three-dimensional surface of the object. Finally, the physical resin model is fabricated.