The aim of this study was to evaluate the stress distribution of monocortical and bicortical implant placement of external hexagon connection in the anterior region of the maxilla by 3D finite element analysis (FEA). 3D models were simulated to represent a bone block of anterior region of the maxilla containing an implant (4.0 × 10.0 mm) and an implant-supported cemented metalloceramic crown of the central incisor. Different techniques were tested (monocortical, bicortical, and bicortical associated with nasal floor elevation). FEA was performed in FEMAP/NeiNastran software using loads of 178 N at 0°, 30°, and 60° in relation to implant long axis. The von Mises, maximum principal stress, and displacement maps were plotted for evaluation. Similar stress patterns were observed for all models. Oblique loads increased the stress concentration on fixation screws and in the cervical area of the implants and bone around them. Bicortical technique showed less movement tendency in the implant and its components. Cortical bone of apical region showed increase of stress concentration for bicortical techniques. Within the limitations of this study, oblique loading increased the stress concentrations for all techniques. Moreover, bicortical techniques showed the best biomechanical behavior compared with monocortical technique in the anterior maxillary area.

The aim of this study was to assess stress/strain of different implant modeling simplifications by 3D-FEA. Three variation of external hexagon implant (Ø3.75 × 10 mm) supporting one molar crown were simulated: A (no threads); B (slightly threads simplification); C (original design). 200 N (axial) and 100 N (oblique) were applied. Cortical bone was evaluated by maximum principal stress and microstrain qualitatively and quantitatively (ANOVA and Tukey post hoc (p < 0.05)). Higher stress levels (p < 0.05) were observed in model A. Models B and C presented similar stress transmission. It was possible to conclude that slightly simplification should be used for studies evaluating stress transferring for bone tissue.

Introduction: There is a high prevalence of dental trauma in patients in need of orthodontic treatment, so it is important the knowledge about the orthodontic approach in cases of traumatized teeth. Thus, this study conducted a systematic review about orthodontic approach in dental trauma. Materials and Methods: Two investigators performed a systematic review with meta-analysis. MEDLINE/PubMed and Cochrane Library supplied relevant data from studies published between February 2004 and September 2015 on the relationship between dental trauma and orthodontic treatment. Results: Susceptibility to pulp necrosis was the dichotomous outcomes measure evaluated by risk ratio (RR) and the corresponding 95% confidence intervals (CI). The quality was evaluated using the Oxford Centre for Evidence-Based Medicine (EbM) guidelines. A search strategy and application of eligibility criteria enabled selection and evaluation of four studies on orthodontic treatment in traumatized teeth. In total, 1.696 patients (average age 11.6 years) with orthodontic treatment over 24.2 months were studied, and 484 had already suffered dental trauma and undergone orthodontic treatment. The primary observed sequelae after orthodontic treatment indicated greater susceptibility to pulp necrosis in traumatized teeth compared to no previous trauma. The patients with orthodontically treated traumatized maxillary incisors were more susceptible to pulp necrosis (RR: 7.6; 95% CI: 3.64 to 15.87; p= 0.00001) compared to patients with previous dental trauma to the maxillary incisors and no subsequent orthodontic treatment. Conclusion: There is no well-established protocol for these cases; such treatment must be careful and respect the healing period post-trauma, when these teeth are more susceptible to pulp necrosis and pulp obliteration. Descriptors: Tooth Injuries; Wounds and Injuries; Tooth Avulsion; Orthodontics, Corrective.

The aim of study was to evaluate the stress distribution in implant-supported prostheses and peri-implant bone using internal hexagon (IH) implants in the premaxillary area, varying surgical techniques (conventional, bicortical and bicortical in association with nasal floor elevation), and loading directions (0°, 30° and 60°) by three-dimensional (3D) finite element analysis. Three models were designed with Invesalius, Rhinoceros 3D and Solidworks software. Each model contained a bone block of the premaxillary area including an implant (IH, Ø4 × 10 mm) supporting a metal-ceramic crown. 178 N was applied in different inclinations (0°, 30°, 60°). The results were analyzed by von Mises, maximum principal stress, microstrain and displacement maps including ANOVA statistical test for some situations. Von Mises maps of implant, screws and abutment showed increase of stress concentration as increased loading inclination. Bicortical techniques showed reduction in implant apical area and in the head of fixation screws. Bicortical techniques showed slight increase stress in cortical bone in the maximum principal stress and microstrain maps under 60° loading. No differences in bone tissue regarding surgical techniques were observed. As conclusion, non-axial loads increased stress concentration in all maps. Bicortical techniques showed lower stress for implant and screw; however, there was slightly higher stress on cortical bone only under loads of higher inclinations (60°).

Impaction of maxillary canines can be prevented by early intervention in the mixed dentition phase after the correct diagnosis of malocclusion, reducing the complexity of the treatment. This article reports the case of a 10-year-old patient who possessed impacted maxillary canines and, after early extraction of primary canines, had reestablished favorable permanent successors' eruption axis. This 5-year radiographic follow-up study with panoramic radiography shows that this can be used in practice and that an effective control strategy ensures the accuracy in the inclination of the impacted canines. Treatment success is related to early diagnosis and strategic interceptive treatment choice.