Clinical validation of a new subtraction radiography technique for periodontal bone loss detection.

BACKGROUND: Diagnostic subtraction radiography (DSR) is a new digital radiographic image subtraction method designed to enhance detection of crestal or periapical bone density changes and to help evaluate caries progression in teeth. In this clinical study, the performance of the DSR method was evaluated for its ability to detect periodontal bone loss and was compared with that of conventional evaluation of radiographs and the standardized cephalostat-guided image acquisition and subtraction technique (LRA) which served as the "gold standard." METHODS: In each of 25 subjects with alveolar crestal bone loss created by periodontal surgery, one set of DSR radiographs and one set of LRA radiographs were obtained before and after the surgery. Subtraction images were then generated by both the proprietary DSR and the LRA techniques. Four viewers evaluated the paired film sets and both subtraction image sets using a 5 point confidence scale to determine the presence or absence of crestal bone loss. Receiver operating characteristics (ROC) statistical procedures were applied to analyze the diagnostic accuracy and statistical differences between the three imaging modalities. RESULTS: The DSR subtraction viewing generated an ROC area of 0.882. For 2 of the viewers this represented a statistically significant gain (P <0.05) over the conventional viewing of the radiographs which had an average ROC area of 0.730. In comparison, the LRA method achieved an area of 0.954. The differences between the LRA and the DSR subtraction methods were not statistically significant, but the statistical power for claiming equality was low ranging from 0.2 to 0.6. CONCLUSIONS: The use of the DSR technique in clinical radiographic image acquisition and subsequent subtraction analysis clearly enhanced the accuracy of alveolar crestal bone loss detection when compared to conventional film viewing. Because this methodology is less resource demanding than LRA and the film exposure techniques and computer-based image analysis skills may be acquired with only a few hours of training, the DSR has potential in clinical practice.

Crestal bone changes around titanium implants. A radiographic evaluation of unloaded nonsubmerged and submerged implants in the canine mandible.

Current implant placement utilizes both nonsubmerged and submerged techniques. However, the implications of the location of a rough/smooth implant interface as well as the location of a microgap between implant and abutment on crestal bone changes are not well understood. The purpose of this study was to radiographically evaluate crestal bone changes around unloaded nonsubmerged and submerged titanium implants in a side-by-side comparison. Fifty-nine (59) implants were placed at different levels to the alveolar crest in 5 foxhounds. Standardized radiographs were taken at baseline and at monthly intervals until sacrifice at 6 months. Radiographic assessment was carried out by measuring the distance between the top of the implant/abutment and the most coronal bone-to-implant contact (DIB), and by evaluation of bone density changes using computer-assisted densitometric image analysis (CADIA). DIB measurements revealed that in 1-part, nonsubmerged implants, the most coronal bone-to-implant contact followed at all time points the rough/smooth implant interface. In all 2-part implants, nonsubmerged and submerged, the most coronal bone-to-implant contact was consistently located approximately 2 mm below the microgap. In addition, CADIA values for all 2-part implants were decreased in the most coronal area-of-interest (AOI). All bone changes were statistically significant and detectable 1 month after implant placement in nonsubmerged implants or 1 month after abutment connection in submerged implants. Neither implant position nor individual dog effects were statistically significant. These results demonstrate that the rough/smooth implant interface as well as the location of the microgap have a significant effect on marginal bone formation as evaluated by standardized longitudinal radiography. Bone remodeling occurs rapidly during the early healing phase after implant placement for non-submerged implants and after abutment connection for submerged implants.

A clinical evaluation of demineralized freeze-dried bone allograft in combination with tetracycline in the treatment of periodontal osseous defects.

The purpose was to evaluate the use of demineralized freeze-dried bone allograft reconstituted with 50 mg/ml tetracycline hydrochloride in the treatment of intrabony periodontal defects. Fifteen systemically healthy patients (12 females, 3 males; aged 35 to 61) with moderate-advanced periodontitis were treated. Patients had 3 osseous defects with probing depths (PD) > 5 mm after initial therapy. Each site in each subject was randomly assigned to one of the following groups: 1) demineralized freeze-dried bone allograft reconstituted with 50 mg/ml tetracycline (DFDBA + TCN); 2) demineralized freeze-dried bone allograft alone (DFDBA); or 3) debridement only (D). Clinical measurements were taken the day of surgery, 6 months, and 1 year. Standardized radiographs were taken at baseline and 1 year and were evaluated by computer assisted densitometric image analysis (CADIA). Clinical measurements included gingival recession, PD, clinical attachment level, and mobility. Osseous defect measurements were taken at baseline and at the 1 year reentry. No adverse healing responses occurred. The results showed that all patients had a statistically significant improvement in probing depth and attachment level at 1 year. Osseous measurements showed bone fill of 2.27 mm (51.6%) for the DFDBA + TCN group, 2.20 mm (52.4%) for the DFDBA group, and 1.27 mm (32.8%) for the D group. Defect resolution was 77.3% for the DFDBA + TCN group, 77.9% for the DFDBA group, and 63.8% for the D group. The mean CADIA values were 5.04 for the DFDBA + TCN group, 6.79 for the DFDBA group and 2.78 for the D group. The CADIA values did not correlate with the clinical parameters. Although the grafted groups showed greater bone fill and defect resolution, there was no statistically significant difference in any of the clinical parameters between the treatment groups. This study suggests that there is no significant benefit from reconstituting the allograft with 50 mg/ml of tetracycline hydrochloride.

The association between estrogen status and alveolar bone density changes in postmenopausal women with a history of periodontitis.

While numerous studies have demonstrated a relationship between 17-beta-estradiol (E2) deficiencies and skeletal bone loss in postmenopausal females, the influence of E2 deficiency on alveolar bone resorption is poorly understood. The purpose of this study was to examine the association between the estrogen status of postmenopausal women and alveolar bone density changes in a 1-year longitudinal study. Twenty-four postmenopausal women, within 7 years of menopause, were divided into 2 groups, E2-sufficient (n = 10) and E2-deficient (n = 14). Venous blood samples were taken at baseline, 6 months, and 1 year for radioimmunoassay determination of serum E2 levels. At baseline and 1 year, 4 vertical bite-wing radiographs were taken for computer-assisted densitometric image analysis (CADIA). Areas of interest (AOIs) for CADIA were crestal and subcrestal regions of posterior interproximal alveolar bone. Serum E2 levels were significantly higher at all 3 time points in the E2-sufficient subjects (P < 0.002), repeated measures ANOVA). Overall, mean CADIA values (0.30 +/- 0.07 for the E2-sufficient women and -0.44 +/- 0.07 for the E2-deficient women) were statistically different between groups (P < 0.001, repeated measures ANOVA), indicating that the E2-sufficient women displayed a mean net gain in alveolar bone density and the E2-deficient women displayed a mean net loss in alveolar bone density. Furthermore, the E2-sufficient women exhibited a higher frequency of sites demonstrating a gain in alveolar bone density, while the E2-deficient women exhibited a higher frequency of sites demonstrating loss in alveolar bone density. These data suggest that estrogen status may influence alveolar bone density changes as demonstrated with CADIA.

Effects of guided bone regeneration around commercially pure titanium and hydroxyapatite-coated dental implants. I. Radiographic analysis.

The purpose of this study was to determine which treatment of a large osseous defect adjacent to an endosseous dental implant would produce the greatest regeneration of bone and degree of osseointegration: barrier membrane therapy plus demineralized freeze-dried bone allograft (DFDBA), membrane therapy alone, or no treatment. The current study assessed radiographic density changes in bone within the healed peri-implant osseous defect. In a split-mouth design, 6 implants were placed in edentulous mandibular ridges of 10 mongrel dogs after preparation of 6 cylindrical mid-crestal defects, 5 mm in depth and 9.525 mm in diameter. An implant site was then prepared in the center of each defect to a depth of 5 mm beyond the apical extent of the defect. One mandibular quadrant received three commercially pure titanium (Ti) screw implants (3.75 X 10 mm), while the contralateral side received three hydroxyapatite (HA) coated root-form implants (3.3 X 10 mm). Consequently, the coronal 5 mm of each implant was surrounded by a circumferential defect approximately 3 mm wide and 5 mm deep. The three dental implants in each quadrant received either DFDBA (canine source) and an expanded polytetrafluoroethylene membrane (ePTFE), ePTFE membrane alone, or no treatment (control). Standardized radiographs were taken at 1 week and 4 months post-implant placement. Computer-assisted densitometric image analysis (CADIA) was performed at 6 areas of interest (coronal, middle, and apical defect areas mesial and distal to each implant) for each of the implant sites. Significantly greater increase in bone density was obtained using DFDBA/ePTFE compared to ePTFE alone or the controls; likewise, ePTFE alone resulted in greater bone density change than the controls. There were no significant differences in radiographic bone density adjacent to Ti versus HA-coated implants. When 3 dogs having postoperative membrane complications were eliminated from the analysis, the results were similar with the exception that defects adjacent to Ti implants had significantly less density gain when compared to HA-coated implants. The results of this study indicate the use of DFDBA/ePTFE in large surgically-created defects promotes a denser healing of bone adjacent to implants when measured radiographically than either ePTFE alone or no treatment.

Hydroxyapatite cement implant for regeneration of periodontal osseous defects in humans.

A newly developed calcium phosphate cement used to promote bone regeneration in craniofacial defects was examined to determine its potential for treatment of periodontal osseous defects. Sixteen patients with moderate to severe periodontal disease and 2 bilaterally similar vertical bony defects received initial therapy including scaling and root planing followed by treatment with either calcium phosphate cement, flap curettage (F/C) or debridement plus demineralized freeze-dried bone allograft (DFDBA). Standardized radiographs were exposed at baseline and 12 months postsurgery for computer assisted densitometric image analysis (CADIA). The extent of the bony defect was determined during initial and 12 month re-entry surgery. Within 6 months of implant placement, 11 of 16 patients treated with calcium phosphate cement exfoliated all or most of the implant through the gingival sulcus. At all 16 test sites, a narrow radiolucent gap formed by 1 month postsurgery at the initially tight visual interface between the radiopaque calcium phosphate cement and the walls of the bony defect. Mean probing depth reduction and clinical attachment gain at sites treated with calcium phosphate cement were 1.6 mm and 1.3 mm, respectively at 1 year. Minimal bony defect fill was accompanied by mean crestal resorption of 1.4 mm. Alveolar crestal resorption at sites with calcium phosphate cement was statistically significant (P=0.001). These findings contrasted with the more favorable outcomes for controls treated with DFDBA or F/C. DFDBA sites exhibited probing depth reduction of 3.1 mm, clinical attachment gain of 2.9 mm, and defect fill of 2.4 mm. Respective clinical changes at F/C sites were 2.4 mm, 1.4 mm, and 1.1 mm. CADIA revealed clinically significant trends between the three treatment modalities at various areas-of-interest. Based on the findings of this study, there is no rationale available to support the use of hydroxyapatite cement implant in its current formulation for the treatment of vertical intrabony periodontal defects.

Quantitative analysis of periodontal defects in a skull model by subtraction radiography using a digital imaging device.

This paper describes a quantitative study of periodontal defects produced in a skull model using subtraction images obtained with a digital imaging device, radiovisiography (RVG). Analysis using radiovisiography was compared to changes in weight and volume determined by physical measurements. Four types of periodontal defects were studied: 2-wall, 3-wall, crater, and furcation. All defects were fabricated on posterior teeth in alveolar bone and done with triplicate samples. Defects were made progressively larger in approximately 1 mm steps allowing examination of defects ranging from 1 mm to 5 mm. Radiographic images before and after each step were obtained with a radiovisiography system and subtracted. Changes in weight and defect volume were also recorded and compared to the results obtained after each step from the digital subtraction. For each defect type, a regression analysis was performed to compare changes in bone mass determined by weight with calculated bone loss determined by subtraction radiography or by volume measurements. When the calculated bone losses were compared to the true bone losses it was evident that the subtraction method frequently, but not always, underestimated the lesion sizes. For all lesions the average underestimation was 22%. The largest underestimation occurred with furcation lesions where the measured bone loss was underestimated on average by 67%. Two-walled lesions were underestimated by 30%, 3-wall lesions by 3%, and crater lesions were overestimated by 10%. Furthermore, the accuracy of each 1 mm step in bone loss varied considerably. At present, the imaging system is not sufficiently accurate to establish absolute determinations of the bone loss, but would be clinically useful in determining relative changes in bone loss or gain after treatment. In addition, caution must be taken in interpreting a given change in calculated bone loss, since considerable variation may result in either underestimation or overestimation of bone loss.

Clinical evaluation of demineralized-unicortical-ilium-strips for guided tissue regeneration.

This study compared demineralized-unicortical-ilium-strips (DUIS) and an expanded polytetrafluoroethylene (ePTFE) physical barrier in combination with decalcified freeze-dried bone allograft (DFDBA) for treatment of Class II mandibular furcations. Twenty patients with adult periodontitis and at least 2 furcation invasions participated in this study. Probing depth (PD), clinical attachment level (CAL), and bone fill were measured at 6 and 12 months. Standardized radiographs were analyzed using computer assisted densitometric image analysis (CADIA). Fifteen of 20 patients completed the 12-month evaluation. At 6 months both control and test groups showed significant reductions in PD from baseline (P < 0.01). PD reduction for the ePTFE + DFDBA sites was 2.13 mm +/- 1.25, and the DUIS + DFDBA, 1.77 mm +/- 1.21. CAL at 6 months was sustained to 12 months when the net gains in CAL for ePTFE + DFDBA being 1.30 mm +/- 1.45 (P < 0.01) and for DUIS + DFDBA sites 1.13 mm +/- 1.68 (P < 0.02). The horizontal furcation PD decreased 2.87 mm +/- 1.68 (P < 0.01) in the ePTFE + DFDBA and 1.70 mm +/- 1.69 (P < 0.01) for DUIS + DFDBA sites over 12 months. The evaluation of the hard tissue response at the 12-month re-entry demonstrated a bone fill of 2.37 mm (75%) +/- 2.04 (P < 0.01) with ePTFE + DFDBA and 1.83 mm (79%) +/- 1.57 (P < 0.01) with DUIS + DFDBA. DUIS material and ePTFE showed significant improvements in clinical parameters and neither material proved to be significantly better. However, a larger sample size may have permitted us to demonstrate statistically significant differences between the materials. The positive results from the utilization of DUIS for GTR and the advantage of its bioresorbability warrant further investigation. The study found limitations in the use of CADIA for evaluation of guided tissue regeneration in furcations.

Clinical evaluation of bioactive glass in the treatment of periodontal osseous defects in humans.

The purpose of this study was to compare the use of bioactive glass to demineralized freeze-dried bone allograft (DFDBA) in the treatment of human periodontal osseous defects. Fifteen systemically healthy patients (6 males and 9 females, aged 30 to 63) with moderate to advanced adult periodontitis were selected for the study. All patients underwent initial therapy, which included scaling and root planing, oral hygiene instruction, and an occlusal adjustment when indicated, followed by re-evaluation 4 to 6 weeks later. Paired osseous defects in each subject were randomly selected to receive grafts of bioactive glass or DFDBA. Both soft and hard tissue measurements were taken the day of surgery (baseline) and at the 6-month re-entry surgery. The clinical examiner was calibrated and blinded to the surgical procedures, while the surgeon was masked to the clinical measurements. Statistical analysis was performed by using the paired Student's t test. The results indicated that probing depths were reduced by 3.07 +/- 0.80 mm with the bioactive glass and 2.60 +/- 1.40 mm with DFDBA. Sites grafted with bioactive glass resulted in 2.27 +/- 0.88 mm attachment level gain, while sites grafted with DFDBA had a 1.93 +/- 1.33 mm gain in attachment. Bioactive glass sites displayed 0.53 +/- 0.64 mm of crestal resorption and 2.73 mm bone fill. DFDBA-grafted sites experienced 0.80 +/- 0.56 mm of crestal resorption and 2.80 mm defect fill. The use of bioactive glass resulted in 61.8% bone fill and 73.33% defect resolution. DFDBA-grafted defects showed similar results, with 62.5% bone fill and 80.87% defect resolution. Both treatments provided soft and hard tissue improvements when compared to baseline (P < or = 0.0001). No statistical difference was found when comparing bioactive glass to DFDBA; however, studies with larger sample sizes may reveal true differences between the materials. This study suggests that bioactive glass is capable of producing results in the short term (6 months) similar to that of DFDBA when used in moderate to deep intrabony periodontal defects.

The accuracy of radiographic methods in assessing the outcome of periodontal regenerative therapy.

BACKGROUND: The study of regenerative therapy in the periodontal intrabony defect has relied upon surgical re-entry as the gold standard of outcome assessment. The search for a non-invasive method has led to the application of various radiographic techniques in evaluating post-treatment bone fill. METHODS: The purpose of this study was to determine the ability of 2 forms of radiographic analyses (linear measurement and computer assisted densitometric image analysis, CADIA) to assess postsurgical bone fill as measured at a re-entry procedure. A method that incorporates linear measurements and CADIA (linear-CADIA) was developed and tested as well. Forty-five intrabony defects in 15 patients were treated with open flap debridement, demineralized freeze-dried bone allograft (DFDBA), or a combination of DFDBA and tetracycline. Standardized radiographs were obtained at baseline and at 1-year postsurgery. RESULTS: A 12-month surgical re-entry provided clinical measurements for post-treatment bone fill. All radiographs were digitally scanned and analyzed on a computer. Fifty-three percent of the defects were excluded from the study due to poor standardization or poor defect quality. Forty percent of all pairs of radiographs were judged to have poor standardization. In the first analysis, standardized images were subtracted and quantitatively analyzed utilizing CADIA. It was found that CADIA had the highest correlation with clinical bone fill when a region of interest (ROI) was examined in the middle portion of the defect. This quantitative evaluation provided very little clinically relevant information regarding actual bone fill. For the second analysis, pre- and post-treatment linear radiographic measurements were obtained. In only 43% of the sites, did linear radiographic measurements determine post-treatment bone fill within 1.0 mm of the clinical measurements. Overall, linear measurements underestimated bone fill by 0.96 mm (+/-1.2). These differences were statistically significant (paired Student t-test, P = 0.0023). A method, which incorporates the use of both CADIA and linear radiographic measurements (linear-CADIA), was tested. The linear-CADIA method underestimated bone fill by 0.26 mm (+/-1.4), but these differences were not statistically significant (paired Student t-test, P = 0.41). CONCLUSION: Linear radiographic measurements significantly underestimate post-treatment bone fill when compared to re-entry data. The linear-CADIA method provided the highest level of accuracy of the 3 methods tested. This study also emphasizes the importance of developing a consistent method of radiographic standardization.

Crestal bone changes around titanium implants: a methodologic study comparing linear radiographic with histometric measurements.

Generally, endosseous implants can be placed according to a nonsubmerged or a submerged technique and in 1-piece or 2-piece configurations. Recently, it has been shown that peri-implant crestal bone reactions differ significantly radiographically as well as histometrically under such conditions and are dependent on a rough/smooth implant border in 1-piece implants and on the location of a microgap (interface) between the implant and the abutment/restoration in 2-piece configurations. The purpose of this study was to evaluate whether standardized radiography as a noninvasive clinical diagnostic method correlates with peri-implant crestal bone levels as determined by histometric analysis. Fifty-nine implants were placed in edentulous mandibular areas of 5 foxhounds in a side-by-side comparison in both submerged and nonsubmerged techniques. Three months after implant placement, abutment connection was performed in the submerged implant sites. At 6 months, all animals were sacrificed, and evaluations of the first bone-to-implant contact (fBIC), determined on standardized periapical radiographs, were compared to similar analyses made from nondecalcified histology. It was shown that both techniques provide the same information (Pearson correlation coefficient = 0.993; P < .001). The precision of the radiographs was within 0.1 mm of the histometry in 73.4% of the evaluations, while the level of agreement fell to between 0.1 and 0.2 mm in 15.9% of the cases. These data demonstrate in an experimental study that standardized periapical radiography can evaluate crestal bone levels around implants clinically accurately (within 0.2 mm) in a high percentage (89%) of cases. These findings are significant because crestal bone levels can be determined using a noninvasive technique, and block sectioning or sacrifice of the animal subject is not required. In addition, longitudinal evaluations can be made accurately such that bone changes over various time periods can be assessed. Such analyses may prove beneficial when trying to distinguish physiologic changes from pathologic changes or when trying to determine causes and effects of bone changes around dental implants.

Radiographic analysis of regenerated bone around endosseous implants in the canine using recombinant human bone morphogenetic protein-2.

Ideal endosseous implant placement involves a congruent bony housing in close apposition to the implant surface. Clinical situations are encountered, however, in which the entire implant surface cannot be in close apposition to bone. In these instances, bone grafting materials are generally used to regenerate bone around the implant. In this study, a biologically active bone differentiation factor, recombinant human bone morphogenetic protein-2 (rhBMP-2), was used with two different carriers to regenerate bone around implants in standardized critical-sized defects in the canine mandible. Half of the sites had a nonresorbable membrane placed over the defect. Longitudinal standardized radiographs were obtained to assess the amount of bone regeneration on the mesial and distal of the implants after 4 and 12 weeks of healing. Ninety-six implants were placed in 12 fox-hounds. Bone fill was determined by linear measurement of bone on the radiographs, and changes in bone density were evaluated by computer-assisted densitometric image analysis of discrete areas adjacent to the implant. After 4 weeks of healing, nonmembrane sites had significantly greater bone height than membrane-protected sites. Following 12 weeks of healing, sites treated with rhBMP-2 had significantly greater bone formation than untreated sites. Sites treated with rhBMP-2 and a membrane had the greatest bone fill, followed by sites treated with rhBMP-2 but no membrane. Sites without rhBMP-2, whether with or without a membrane, had less bone fill than sites with rhBMP-2. At 12 weeks, sites with a membrane resulted in significantly more gain in bone density than sites without a membrane. Furthermore, sites treated with a collagen carrier resulted in greater gains in bone density than sites treated with a polylactide/glycolide carrier. The results from this study demonstrate by radiographic evidence that new bone formation in critical-sized defects around implants is dependent on time after defect treatment, the type of carrier used, the use of a barrier membrane, and the presence of rhBMP-2. In addition, these findings suggest that rhBMP-2, a bone differentiation factor, can significantly stimulate bone formation around endosseous dental implants.

Radiographic absorptiometry method in measurement of localized alveolar bone density changes.

OBJECTIVE: The objective of this study was to measure the accuracy and precision of a radiographic absorptiometry method by using an occlusal density reference wedge in quantification of localized alveolar bone density changes. STUDY DESIGN: Twenty-two volunteer subjects had baseline and follow-up radiographs taken of mandibular premolar-molar regions with an occlusal density reference wedge in both films and added bone chips in the baseline films. The absolute bone equivalent densities were calculated in the areas that contained bone chips from the baseline and follow-up radiographs. The differences in densities described the masses of the added bone chips that were then compared with the true masses by using regression analysis. RESULTS: The correlation between the estimated and true bone-chip masses ranged from R = 0.82 to 0.94, depending on the background bone density. There was an average 22% overestimation of the mass of the bone chips when they were in low-density background, and up to 69% overestimation when in high-density background. The precision error of the method, which was calculated from duplicate bone density measurements of non-changing areas in both films, was 4.5%. CONCLUSIONS: The accuracy of the intraoral radiographic absorptiometry method is low when used for absolute quantification of bone density. However, the precision of the method is good and the correlation is linear, indicating that the method can be used for serial assessment of bone density changes at individual sites.

Magnetic resonance imaging: practical theory and clinical relevance.

Magnetic resonance imaging can be a valuable diagnostic tool. Some fundamental concepts behind MRI are discussed, using clinical cases to illustrate the potential of this imaging system.

A feasibility study evaluating rhBMP-2/absorbable collagen sponge for maxillary sinus floor augmentation.

This 16-week open-label study assessed the safety and technical feasibility of implanting human recombinant bone morphogenetic protein-2 delivered on an absorbable collagen sponge (rhBMP-2/ACS) for two-stage maxillary floor sinus augmentation. This first use of rhBMP-2/ACS in human clinical maxillary sinus floor augmentation included 12 patients with inadequate bone height in the posterior maxilla. The total delivered dose of rhBMP-2 implanted varied from 1.77 to 3.40 mg per patient. The rhBMP-2/ACS device was easily handled. Significant bone growth was documented by computerized tomographic scans in all evaluable patients (11/12). The overall mean height response for the maxillary sinus floor augmentation was 8.51 mm (95% confidence interval 6.07 to 10.95). There were no serious or unexpected immunologic or adverse effects and no clinically significant changes in complete blood counts, blood chemistries, or urinalysis results. The most frequent adverse effects were facial edema, oral erythema, pain, and rhinitis. Eleven patients have received dental implants and follow-up examinations are still being conducted. Histologic examinations of core bone biopsies obtained at the time of dental implant placement confirmed the quality of the bone induced by rhBMP-2/ACS. These results tend to indicate that rhBMP-2/ACS may provide an acceptable alternative to traditional bone grafts and bone substitutes for maxillary sinus floor augmentation procedures in humans.

A feasibility study evaluating rhBMP-2/absorbable collagen sponge device for local alveolar ridge preservation or augmentation.

This two-center human clinical trial evaluated recombinant human bone morphogenetic protein-2 delivered in an absorbable collagen sponge (rhBMP-2/ACS) for either alveolar ridge preservation after tooth extraction or augmentation of localized osseous defects. This 24-month study comprised two parts: a 4-month acute safety and bone induction period (Part I) followed by a 20-month, osseointegration, functional restoration, and long-term safety evaluation (Part II). The primary objective of Part I, discussed in this article, was to evaluate the short-term safety and technical feasibility of the rhBMP-2 device implantation. Twelve patients (six preservation and six augmentation) were enrolled in the investigation. Patient safety was monitored by oral examinations, radiographs, and the collection of blood samples to measure serum chemistries, hematology, and potential antibody formation. Technical feasibility was evaluated by collecting information relating to the handling properties of the rhBMP-2/ACS device. The ability of various evaluative tools to measure the bone-inducing activity of the rhBMP-2/ACS device was also assessed. The clinical results suggested that rhBMP-2/ACS was well tolerated locally and systemically, with no serious adverse events. The device was found to be easily handled and adapted to the ridge and extraction socket. Using direct measurements, all sites demonstrated firmness and fullness to palpation at 4 weeks; however, a loss of volume was noted in some treatment areas between 4 and 8 weeks. Augmentation of the alveolar ridge was not observed in the patients as assessed by the evaluation techniques. This trial indicated that the use of rhBMP-2/ACS to preserve alveolar ridge after tooth extraction or augmentation of localized defects is safe and feasible. Bone fill was observed in all alveolar sockets filled with the rhBMP-2 device.

Serum bone biomarkers and oral/systemic bone loss in humans.

UNLABELLED: We recently reported that subantimicrobial-dose doxycycline (SDD) significantly reduced serum bone-resorption biomarkers in subgroups of post-menopausal women. We hypothesize that changes in serum bone biomarkers are associated not only with systemic bone mineral density (BMD) changes, but also with alveolar bone changes over time. One hundred twenty-eight eligible post-menopausal women with periodontitis and systemic osteopenia were randomly assigned to receive SDD or placebo tablets twice daily for two years, adjunctive to periodontal maintenance. Sera were analyzed for bone biomarkers. As expected, two-year changes in a serum bone biomarker were significantly associated with systemic BMD loss at the lumbar spine (osteocalcin, bone-turnover biomarker, p = 0.0002) and femoral neck (osteocalcin p = 0.0025). Two-year changes in serum osteocalcin and serum pyridinoline-crosslink fragment of type I collagen (ICTP; bone-resorption biomarker) were also significantly associated with alveolar bone density loss (p < 0.0001) and alveolar bone height loss (p = 0.0008), respectively. Thus, we have shown that serum bone biomarkers are associated with not only systemic BMD loss, but with alveolar bone loss as well. CLINICAL TRIAL REGISTRATION INFORMATION: Protocol registered at ClinicalTrials.gov, NCT00066027.

Evaluation of high-resolution cone beam computed tomography in the detection of simulated interradicular bone lesions.

OBJECTIVES: The purpose of this study is to assess the accuracy of limited-volume high-resolution cone beam CT (CBCT) in the detection of periodontal bone loss. METHODS: 163 simulated periodontal lesions of different depths were created in dried human hemimandibles. Specimens were imaged using the intraoral paralleling technique and limited-volume CBCT (3DX Accuitomo; Morita Co. Ltd, Kyoto, Japan). Ten viewers examined the images. Data were analysed with receiver operating characteristics (ROC) analysis. ROC curves were generated and the areas under the maximum-likelihood curves (A(z)) were compared. Other statistical analyses were used to detect the normality of the distribution of the results. RESULTS: The results are reported as the individual viewer ROC curve areas for each of the two imaging modalities. In all experiments the A(z) area for CBCT (0.770-0.864) was larger than the A(z) area for periapical film (0.678-0.783); statistical tests showed a statistically significant difference between the two modalities. CONCLUSIONS: Results indicate that the CBCT technique has better accuracy and diagnostic value than periapical films in the detection of interradicular periodontal bone defects.

Geometric analysis of occlusal plane orientation using simulated ear-rod facebow transfer.

PURPOSE: Ear-rod facebow techniques may position casts high or low between the upper and lower members on the articulator when using orbitale or nasion as anterior reference positions. This study assessed the effect of changing the anterior reference position on simulated mountings utilizing simulated ear-rod facebow. MATERIALS AND METHODS: Tracings from latoral cephalographs made on seven subjects were superimposed with an outline model of a semiadjustable articulator. Three simulated mountings were performed for each subject in which the plane of occlusion was positioned (1) high, (2) midway, and (3) approaching the lower member (low). Maxillary and mandibular occlusal planes representing intercuspal position were determined from the cephalographs and positioned on the articulator model in a simulated centric relation position for each mounting. Condylar guidance was determined from a simulated protrusive position. RESULTS: Analysis of the three mounting positions demonstrated no change in intercuspal position within subjects; however, angles formed between upper member and condylar guidance were 14.9% smaller for the mid-distance mounting, 42.9% smaller for the high mounting, and 13.4% higher for the low mounting positions when compared with a standard Frankfort horizontal plane reference. CONCLUSIONS: The cephalographs showed extreme variability in the position of the ear piece to bony structures of the skull, but this deviation appeared to be compensated by a change in the horizontal condylar guidance relative to mounting. Results also suggest that casts may be mounted in a convenient mid-position for routine articulation.