Bone formation in sinus augmentation procedures using autologous bone, porcine bone, and a 50 : 50 mixture: a human clinical and histological evaluation at 2 months.

OBJECTIVES: The aim of this study was to perform a 2 months clinical and histological comparison of autologous bone, porcine bone, and a 50 : 50 mixture in maxillary sinus augmentation procedures. MATERIALS AND METHODS: A total of 10 consecutive patients, undergoing two-stage sinus augmentation procedures using 100% autologous bone (Group A), 100% porcine bone (Group B), and a 50 : 50 mixture of autologous and porcine bone (Group C) were included in this study. After a 2-month healing period, at the time of implant insertion, clinical evaluation was performed and bone core biopsies were harvested and processed for histological analysis. RESULTS: The postoperative healing was uneventful regardless of the materials used for the sinus augmentation procedures. The histomorphometrical analysis revealed comparable percentages of newly formed bone, marrow spaces, and residual grafted material in the three groups. CONCLUSION: The clinical and histological results of this study indicated that porcine bone alone or in combination with autologous bone are biocompatible and osteoconductive materials and can be successfully used in sinus augmentation procedures.

Morphological and topographical characteristics of posterior supernumerary molar teeth: an epidemiological study on 25,186 subjects.

OBJECTIVES: To investigate the prevalence , gender difference , arch , morphology and position within the arch of supernumerary molar (SM) teeth in a referred Italian Caucasian population. STUDY DESIGN: Records of 25,186 young patients were evaluated. Only data related to supernumerary teeth in the posterior region of the jaws were analyzed. The diagnosis of hyperdontia was formulated during the clinical and radiological examinations based on panoramic radiographs. Statistical analysis was conducted at level of subjects in the assessment of prevalence of SMs and sex ratio. Statistical analysis was conducted at level of teeth according to their morphological and topographic characteristics. The analysis of association between supernumerary morphology and arch, between supernumerary position and arch and between morphology and position was performed using the χ2 test (P≤ 0.05). RESULTS: 61 posterior supernumerary teeth were found in 45 patients. The male to female ratio was 2.5:1 ;the mean age was 21.23 (IC:95%).The SMs were found more frequently in the maxilla (62.3%) than in the mandible; supernumerary teeth (60.7%) were more frequent than supplemental teeth. The SMs were mostly of tuberculate shape (56.8%) and paramolars teeth (64.9%) were more common than distomolars. 54% of teeth were erupted in the arch. No statistically significant relationship were found between the supernumerary teeth shape and the arch (P= 0.087) , between supernumerary teeth position and the arch (P=0.511) and between morphology and position (P=0.216). CONCLUSIONS: Epidemiological studies related to supernumerary teeth can be useful to clinicians in the early diagnosis of this anomaly. In this retrospective study the prevalence of SMs was 0.18%. SMs were more frequent in males and in the maxilla. Supernumerary were more frequent than supplemental; the conical morphology and paramolar position were the most common shape and position.

A 36-month follow-up prospective cohort study on peri-implant bone loss of Morse Taper connection implants with platform switching.

A prospective cohort study was designed to measure marginal bone level changes at 36-month follow-up and to evaluate the influence of biologically relevant, anatomic and stress-related variables. STROBE guidelines were followed. Totally, 748 implants were inserted into 350 patients. Standardized periapical radiographs were taken at 2- (stage-two surgery), 12-, 24-, and 36-month follow-ups. Descriptive statistics were used and inter- and intra-examiner reliability were determined. A mixed-model was used to evaluate predictor variables. Statistical analysis was performed at implant level (statistical significance: P < 0.05). A total of 34 (4.5%) implants failed; of the 34 implants, 6 were early failures (0.8%) and 28 were late failures (3.7%). A total of 576 implants reached 36-month follow-up (mean follow-up: 25.58 months; SD: 10.32). Mean marginal bone remodeling was -0.56 mm. (SD: 1.30; range: -6.80 ± 3.65). A statistically significant, higher marginal bone loss was found for subcrestal implants and subcrestal implants inserted into the maxilla, for implants inserted into patients aged over 50 years, and for early-delayed implants inserted into patients aged over 50 years. In conclusion, a low, mean crestal bone loss at 36-month follow-up was recorded but implant positioning in the apico-occlusal dimension was found to be the most significant variable that influenced bone loss. (J Oral Sci 58, 49-57, 2016).

Etiological factors in second mandibular molar impaction.

OBJECTIVES: The impaction of the second mandibular molar (MM2) has recently become more prevalent. Several etiological hypothesis have been proposed to investigate the association between skeletal features and impaction of MM2. The aims of this study were to analyze the skeletal features in patients with MM2 impaction and the association between arrested eruption of MM2 and the presence of the third mandibular molar (MM3). STUDY DESIGN: In this retrospective study 48 subjects from 3,530 Caucasian orthodontic patients with MM2 impaction were included in a study group (SG) and compared to a control group (CG) of 200 subjects without MM2 impaction. Panoramic radiographs evaluated the presence or absence of the MM3 germ. Cephalometric analysis was performed to evaluate linear and angular skeletal values. For the statistical analysis, descriptive statistics, Student's t-test, χ2 test and odds ratio (OR) were used. RESULTS: The paired comparisons between SG and CG showed in cephalometric analysis both a reduced mandibular gonial angle (ArGoMe) and lowered Jarabak's polygon value with a statistically significant difference (P≤ 0.05). MM3 was statistically significant associated (P≤ 0.05) with MM2 impaction but it is not a risk factor (OR 0.817). CONCLUSIONS: Subjects with MM2 impaction show a vertical condylar growth direction. MM3 is not a risk factor for MM2 impaction. Key words:Impacted mandibular second molar, skeletal features, orthodontic.

Accuracy of two stereolithographic surgical templates: a retrospective study.

BACKGROUND: The use of computer software and stereolithography for dental implant therapy has significantly increased during the last few years. The aim of this study was to evaluate and compare the mean accuracy and maximum deviations values of dental implant placement using two stereolithographic (SLA) guide systems. MATERIALS AND METHODS: Twenty patients were selected and 227 implants were inserted using bone-, tooth- and mucosa-supported SLA surgical guides. Thirty-one guides, both single- and multiple-type, were used. Some of the single-type surgical guides were fixed with osteosynthesis screws. A postoperative computer tomography (CT) was performed and an iterative closest point algorithm was used to match the jaw of the CT preoperative with the jaw of the postoperative CT. Quantitative data of each group were described. The t-test was used to determine the influence of the utilization of the different types of SLA on accuracy values. RESULTS: t-Test demonstrated a better accuracy of the multiple-type guides in almost all deviation values when the mucosa-supported guides were considered. Regarding the bone-supported template, the single-type fixed group showed a better accuracy while the highest values of deviation were registered by the multiple-type guides. The single-type group showed a better accuracy when the tooth support was considered. CONCLUSIONS: The results of the present study indicated best accuracy of the single-type guide using a bone or tooth support. The multiple-type guide recorded the best accuracy data when the mucosa support was considered comparing either a fixed and a not-fixed single-type guide.

Accuracy of a computer-aided implant surgical technique.

The purpose of this in vivo retrospective study was to evaluate the accuracy of a computer-designed stereolithographic surgical guide. One hundred eleven implants were placed in 10 patients. Pre- and postoperative computed tomography images were compared using specific software. Global, angular, depth, and lateral deviations were calculated between planned and placed implants. Mean global deviations between planned and placed implants at the coronal and apical aspects were 1.52 mm (range, 0.13 to 3.00 mm) and 1.97 mm (range, 0.34 to 4.23 mm), respectively, while the mean angular deviation was 4.68 degrees (range, 0.10 to 15.25 degrees). This study highlighted a reasonable mean accuracy with relatively high maximum deviations between the postoperative position and the preoperative plan. These results should serve as a warning for the clinician if implants are placed near vital structures.

Accuracy of implant placement with a stereolithographic surgical template.

PURPOSE: The possible advantages of stereolithographic (SLA) surgical template use have not been adequately demonstrated, and studies of the accuracy of computer-aided implant placement are few. The purpose of this in vivo study was to evaluate the accuracy of a computer-designed (SLA) surgical guide by comparing the three-dimensional positions of planned and placed implants. MATERIALS AND METHODS: One hundred sixteen implants were inserted in partially and completely edentulous patients using multiple SLA templates. Preoperative and postoperative computed tomographic images were compared. Four deviation parameters--global, angular, depth, and lateral--were defined and calculated between the planned and actual implant positions and analyzed statistically. RESULTS: The mean global deviations between planned and actual implant positions at the coronal and apical ends were 1.47 mm and 1.83 mm, respectively; the mean angular deviation was 5.09 degrees. There were significant linear correlations at the implant level between coronal and angular deviations and between coronal and apical deviations. CONCLUSIONS: The study highlighted deviations between the postoperative position and the preoperative plan at the coronal and apical portions of the implant, as well as in the angulation of the implant. Although the reported deviation values were extremely high, they do not appear to have resulted in important clinical complications. This suggests the necessity of always keeping a safety zone of at least 2 mm to avoid critical anatomical structures.

Use of piezosurgery during maxillary sinus elevation: clinical results of 40 consecutive cases.

The aim of this study was to evaluate the performance of piezoelectric devices during sinus elevation to determine the percentage of sinus membrane perforation and the time required to perform the antrostomy and elevation of the membrane. A total of 35 patients and 40 grafted sinuses were included. The parameters recorded were bony window length and height, bone thickness, osteotomy area, operative time, and number of perforations. Seven (17.5%) membrane perforations were observed, which were repaired with resorbable membranes. The mean length, height, and thickness of the osteotomy were 13.8 ± 2.9 mm, 6.9 ± 1.4 mm, and 1.4 ± 0.4 mm, respectively. The mean osteotomy area was 96.8 ± 32.2 mm(2), and the mean operative time was 10.3 ± 2.1 minutes. This study demonstrated that a piezoelectric device could be an attractive alternative for successful sinus augmentation.