Photoelastic analysis of conventional and locking system for treatment of mandibular angle fractures with a single plate.

BACKGROUND: This photoelastic analysis evaluated stress distribution in different osteosynthesis systems, conventional and locking, used for treatment of mandibular angle fractures with a single plate. MATERIAL AND METHODS: Angle fractures were simulated in mandibles made of photoelastic resin. Following Champy's method, plate osteosynthesis was performed. The samples were divided into five groups: Group 1, non-fractured mandible; Group 2, two screws were installed in each segment using a conventional system; Group 3, two screws were installed in each segment using a locking system; Group 4, three screws were installed in the proximal segment and four screws in the distal segment using a conventional plate; Group 5, three screws were installed in the proximal segment and four screws in the distal segment using a locking plate. In an universal testing machine coupled to a polariscope, a load was applied to the first molar 10 times. The 50 images were randomly numbered and analyzed qualitatively and quantitatively by two raters. RESULTS: The locking system promoted better stress distribution along the osteosynthesis. The locking system reduced stress magnitude in the distal segment, with a significant between-group difference (P≤ 0.001). CONCLUSIONS: The locking plate/screw system can distribute stress more evenly throughout the osteosynthesis, especially when long seven-hole plates are used. Key words:Internal fracture fixation, osteosynthesis, mandibular fracture, bone plates.

Influence of anti-allergic drugs used systemically on the process of root resorption during delayed tooth replantation: A study in rats.

BACKGROUND/AIM: Anti-allergic drugs can inhibit the hard tissue resorption process, and due to similarities between root resorption and bone mechanisms, it can be inferred that these drugs may also control root resorption. The aim of this study was to analyze the effects of anti-allergic drugs used systemically on the process of root resorption following delayed tooth replantation. MATERIALS AND METHODS: Thirty-two maxillary right incisors of rats were extracted and subsequently replanted. Rats were divided into four groups according to the anti-allergic drug administered: the rats in groups DEX, Q, and MO were treated systemically with dexamethasone phosphate, quercetin, and montelukast, respectively, and no systemic medication was administered to rats in group C. After 60 days, the animals were euthanized, and the specimens were processed for histomorphometric and immunohistochemical analyses. Statistical significance was set at P < .05. RESULTS: There were no significant differences between the groups in terms of inflammatory resorption, replacement resorption, or presence of tartrate-resistant acid phosphatase. In terms of events occurring in the periodontal ligament space, there was a difference between groups Q and MO due to the presence of dental ankylosis and inflammatory connective tissue (P < .05). A difference in inflammatory cells was also observed through CD45 immunolabeling between the DEX and Q groups when compared to the C group (P < .05). CONCLUSION: The systemic administration of anti-allergic drugs did not have an effect on the process of root resorption following delayed tooth replantation.

Evaluation of Knowledge of Physical Education Students on Dental Trauma.

INTRODUCTION: Sports' practitioners are vulnerable to dental trauma; if this occurs, the emergency treatment should be fast and efficient. This may be performed by any person at the site of the accident, not only by dental professionals. Physical educators may face dental trauma and should be able to provide proper care. This study had the objective evaluated the knowledge of physical education graduates on dental trauma. MATERIALS AND METHODS: A questionnaire containing questions on dental trauma was applied to 199 physical education students; after collection of the questionnaires, data were tabulated and processed on the software Epi Info 2000 (Centers for Disease Control and Prevention, 1600 Clifton Rd., Atlanta, GA 30333, USA). As a result, only 36.7% of participants would take the individual suffering trauma to the dental professional, 56.8% believe that the avulsed tooth should be replanted, and 42.2% would replant it. Only 7.5% would store the avulsed tooth in an ideal storage medium for transportation. CONCLUSION: It was concluded that there is a lack of knowledge on dental trauma among physical education graduates, evidencing the need of public policies to allow education on this issue.

Tomographic Analysis of the Impact of Mandibular Advancement Surgery on Increased Airway Volume.

PURPOSE: This study aimed to quantify, using cone-beam computed tomography (CBCT) in patients who underwent a mandibular advancement surgery associated with genioplasty, three-dimensional changes in airway space and to evaluate whether these changes differ between men and women. MATERIALS AND METHODS: Preoperative and 8-month postoperative CBCT scans of 38 patients aged 18-45 years of either sex and any ethnicity who underwent mandibular advancement surgery associated with genioplasty were analyzed using the Xoran software (Xoran Technologies, Ann Arbor, MI, USA). The linear distances gonion-gnathion (Go-Gn) and condylion-menton (Co-Me) were obtained. Airway volume was measured using the Dolphin Imaging software, version 11.0. Then, data were tabulated and analyzed using Student's t-test. RESULTS: Mean patient age was 30.3 years; 39.47% were men and 60.63% were women. The mean Go-Gn distance was 72.05 mm before surgery and 78.56 mm after surgery, with a mean gain of 6.51 mm. The mean Co-Me distance was 113.47 mm before surgery and 119.89 mm after surgery, with a mean increase of 6.42 mm. Both differences were statistically significant. The mean volume of airway space was 17,272.92 mm3 before surgery and 24,173.74 mm3 after surgery, with a statistically significant mean increase of 6900.82 mm3. There was no statistically significant difference in mean volumetric gain between men (7566.69 mm3) and women (7456.69 mm3). CONCLUSION: Mandibular advancement surgery results in significant increase of airway space, and there is no difference in airway volume between men and women.

Magnetic Field Effects on Bone Repair after Calcium Phosphate Cement Implants: Histometric and Biochemistry Evaluation.

OBJECTIVE: This work evaluated histologic and biochemically the effect of magnetic field buried in bone repair after autogenous bone graft and calcium phosphate cement implants. METHODOLOGY: Bone defects with 5,0 mm of diameter in the cranium of Wistar mice were used to analyse. These mice were submitted to different interventions: autogenous bone graft and calcium phosphate cement implants, both with and without magnetic stimulation. Longitudinal and transversal histometric and biochemistry analysis were made in times of 15, 30 and 60 post-operative days. RESULTS: The histometric transversal analysis did not show significant differences in the bone repair between groups. Longitudinally, significant difference were found in the quantity of neoformed bone between the times 15 and 60 post-operative days in the autogenous bone graft group under magnetic stimulation. The alkaline phosphatase enzyme presented a higher activity in 30 post-operative days and the groups under magnetic stimulation presented reduced enzymatic activity in comparison to the other groups. CONCLUSION: The permanent and static magnetic field promoted significant differences in the neoformed bone in the groups autogenous bone graft.

Biocompatibility evaluation of biodentine in subcutaneous tissue of rats.

INTRODUCTION: Biodentine (Septodont, St-Maur-des-Fossés, France) is a new material suitable for various clinical situations in endodontics, such as perforation repair, retrograde filling, pulp capping, and others. Because it is a new material, its properties should be analyzed before routine clinical use. Thus, this study evaluated the biocompatibility of Biodentine in the subcutaneous tissue of rats. METHODS: This study was conducted on 15 male rats. Two incisions were made on the dorsal region of each animal for the introduction of 4 tubes. One tube was empty, 1 was filled with zinc oxide-eugenol cement, 1 was filled with mineral trioxide aggregate, and the last tube was filled with Biodentine. After 7, 14, and 30 days, the animals were sacrificed, and the specimens were submitted to histotechnical preparation. The histologic sections were stained with hematoxylin-eosin and analyzed using light microscopy. Scores were established according to the inflammatory process and were statistically compared using the Kruskal-Wallis test (P < .05). RESULTS: The analysis of the histologic sections evidenced a nonsignificant or mild presence of inflammatory reaction in the connective tissue in contact with the empty tube and the tube containing MTA, which was different from the tube containing zinc oxide eugenol. The connective tissue was moderately inflamed at 7 days when in contact with Biodentine; however, at 14 and 30 days, the inflammatory process was mild or nonsignificant. CONCLUSIONS: Biodentine was biocompatible with tissue after the 14th day.