Avaliação da densidade óssea para instalação de mini-implantes

INTRODUÇÃO: além da espessura da cortical óssea e da largura dos espaços inter-radiculares, a densidade óssea é fator primordial para a eficiência dos mini-implantes usados como recurso de ancoragem. OBJETIVO: nesse estudo, pretendeu-se avaliar a densidade óssea alveolar e basal maxilar e mandibular, em unidades Hounsfield (HU). MÉTODOS: em onze arquivos de imagens tomográficas computadorizadas Cone-Beam, de indivíduos adultos, foram obtidas 660 medidas das densidades ósseas alveolar (corticais vestibular e lingual), do osso medular e basal (maxilar e mandibular). Os valores foram obtidos através do software Mimics 10.01 (Materialise, Bélgica). RESULTADOS: maxila - a densidade da cortical vestibular na faixa de osso alveolar variou de 438 a 948HU, e a lingual de 680 a 950HU; já o osso medular variou de 207 a 488HU; a densidade da cortical vestibular na faixa de osso basal apresentou uma variação de 672 a 1380HU e o osso medular de 186 a 420HU. Mandíbula - a variação do osso na cortical vestibular na faixa de osso alveolar foi de 782 a 1610HU, na cortical lingual alveolar de 610 a 1301HU, e na medular de 224 a 538; a densidade na área basal foi de 1145 a 1363HU na cortical vestibular, e de 184 a 485HU na medular. CONCLUSÕES: a maior densidade óssea na maxila foi observada entre pré-molares na cortical alveolar vestibular. A tuberosidade maxilar foi a região com menor densidade óssea. A densidade óssea na mandíbula foi maior do que na maxila, e observou-se um acréscimo progressivo de anterior para posterior e de alveolar para basa

Influence of saliva contamination on the shear bond strength of adhesives on enamel

OBJECTIVE: To evaluate shear bond strength of 3 adhesive systems (Single Bond, TransbondTM MIP and TransbondTM XT) applied on bovine enamel under saliva contamination condition. METHOD: One hundred and twenty enamel surfaces of bovine incisors were divided into 6 groups (n = 20) according to the adhesive system used (TransbondTM XT, TransbondTM MIP and Single Bond) with or without saliva contamination. For each adhesive system, there were two groups defined as no contamination group (NC): 37% H3PO4 conditioning for 30 seconds and two layers of adhesive systems; saliva contamination group (SC): After the first adhesive layer application, the examined areas were contaminated with saliva. Samples were mounted appropriately for testing and stored in deionized water at 37 ºC for 7 days. Samples were then submitted to shear bond strength trials at a speed of 0.5 mm/min. The Adhesive Remnant Index (ARI) was evaluated under stereomicroscopy. Two-way analysis of variance and the Tukey test were used to compare mean values (&#945; = 0.05). RESULTS: Groups XT (NC) = 26.29 ± 7.23; MIP (NC) = 24.47 ± 7.52 and SB (NC) = 32.36 ± 4.14 XT (SC) = 19.59 ± 6.76; MIP (SC) = 18.08 ± 6.39 and SB (SC) = 18.18 ± 7.03 MPa. ARI 0 and 1 were the most prevalent scores in all study groups examined. CONCLUSION: Saliva contamination significantly decreased bond strength of the three adhesive systems examined (p <0.05). However, the comparison of groups with and without saliva contamination did not reveal any significant differences, and, therefore, the three systems may be considered equivalent

The facial profile in brazilian adults

investigate if there is agreement between measurement values obtained for Brazilian adults and the values recommended by Holdaway, Merrifield, Burstone, Steiner and Ricketts, for facial profile soft tissue analysis. METHODS: A sample of 30 cephalometric radiographs was used, consisting of 15 women and 15 men, aged 18 to 31 years, all exhibiting excellent occlusion and balanced facial profile. Comparisons were made with the measurement values proposed by the aforementioned authors using Students t-test and to determine the correlation between the ANB and Â-H measurement values described by Holdaway, using Pearson\u27s correlation coefficient. RESULTS: Among the measures evaluated, 4 showed statistically significant differences: Â.Z (Merrifield), S-LS and S-LI (Steiner), and E-LI (Ricketts) relative to the standards recommended by the authors. The measurement values advocated by Merrifield, Steiner and Ricketts showed statistical differences, and as for the Z-angle, Brazilians feature a slightly more convex profile, which appeared slightly concave according to Steiner, and according to the E-Plane (Ricketts), it meant an increased protrusion of the lower lip. CONCLUSION: It could be asserted that adult Brazilians have a slightly more convex facial profile than US standards, but these differences should be viewed with caution, as they are clinically unimportant

Morphological evaluation of the active tip of six types of orthodontic mini-implants

OBJECTIVE: To morphologically evaluate the active tip of six different types of self-drilling mini-implants for orthodontic anchorage. METHODS: Images of the active tips of the mini-implants were obtained with a Zeiss optical microscope, Stemi 200-C with magnification of 1.6X. The images of the surface were viewed with the Axio Vision program (Zeiss, Jena, Germany) to calculate linear and angular measures. Mini-implant morphology and the details of tips and threads were also evaluated through Scanning Electronic Microscopy (SEM) (JEOL, model JSM5800 LV - JEOL, Tokyo, Japan) with magnifications of 90X and 70X, respectively. The evaluation of the mini-implant taper shape was assessed using to the formula: (b - a) / (2 x D). RESULTS: The following variables were measured: (1) active tip width, (2) major diameter of external thread, (3) minor diameter of internal thread and taper of the mini-implant, (4) number of threads and lead of the screw, (5) angle of thread, (6) flank width and (7) pitch width. CONCLUSION: Mini-implants from different manufacturers presented active tips with different characteristics. Mechanical testing is necessary to cor-relate the analyzed characteristics aiming to determine the best performance

Influence of certain tooth characteristics on the esthetic evaluation of a smile

OBJECTIVE: To assess the influence of certain dental characteristics on the perception of smile esthetics by undergraduate dentistry students. METHODS: Ten digital photographs of a woman's smile were modified using Adobe Photoshop software. The following changes were performed: stain removal; incisal edge straightening; gingival leveling; closure of black triangles. A group of 60 undergraduate dental students evaluated the original photograph and the altered images using a visual analog scale to evaluate smile esthetics. Intraexaminer agreement was checked for 30 examiners using the Student t test; for casual error, the Dahlberg formula was used. Data were described as means and standard deviations, and reported in tables. RESULTS: There were no statistically significant differences between the first and second scores assigned by examiners (p>0.05) in any of the comparisons made. The results of systematic error for the method indicated that the measures obtained were reliable. ANOVA was used to test equality of means, and the level of significance was set at 5%. Equality of variances was evaluated using Levene's test, and results revealed that variances were equal. Multiple comparisons using the Tukey's test revealed statistical significance at a 5%level for the presence of black triangular space. No significant values were found for other comparisons. CONCLUSIONS: Some dental characteristics were perceived by undergraduate students, and the black triangular space was classified as the most unfavorable characteristic

Comparison of two scales for evaluation of smile and dental attractiveness

OBJECTIVE: To compare the visual analogue scale (VAS) and the simplified Q-sort method used to investigate the highest level of agreement among dentists, orthodontists and laypeople when assessing smile and dental attractiveness. MATERIAL AND METHODS: An album containing 258 photos of 86 individuals with their lips at rest, a slight and broad smile, was assessed by 25 dentists (general clinicians and various specialties), 23 orthodontists and 27 laypeople with regard to smile and dental attractiveness. To this end, both VAS and simplified Q-sort method were used. Agreements were calculated by intraclass correlation coefficient (ICC). RESULTS: For the single measurement between the VAS method and the simplified Q-sort method, all simplified Q-sort rates were higher in all groups. The simplified Q-sort method results ranged between 0.42 and 0.49 while those of the VAS method varied between 0.37 and 0.42. The simplified Q-sort method also presented higher mean measurement values (0.95 and 0.96) in comparison to VAS (0.94 and 0.95). CONCLUSIONS: Both scales may be considered reliable for evaluating smile and dental attractiveness; however, the simplified Q-Sort method presented slightly higher values than the VAS method

Fracture strength of orthodontic mini-implants

ABSTRACT Objective: This study aimed at evaluating the design and dimensions of five different brands of orthodontic mini-implants, as well as their influence on torsional fracture strength. Methods: Fifty mini-implants were divided into five groups corresponding to different manufactures (DEN, RMO, CON, NEO, SIN). Twenty-five mini-implants were subjected to fracture test by torsion in the neck and the tip, through arbors attached to a Universal Mechanical Testing Machine. The other 25 mini-implants were subjected to insertion torque test into blocks of pork ribs using a torquimeter and contra-angle handpiece mounted in a surgical motor. The shape of the active tip of the mini-implants was evaluated under microscopy. The non-parametric Friedman test and Snedecor’s F in analysis of variance (ANOVA) were used to evaluate the differences between groups. Results: The fracture torque of the neck ranged from 23.45 N.cm (DEN) to 34.82 N.cm (SIN), and of the tip ranged from 9.35 N.cm (CON) to 24.36 N.cm (NEO). Insertion torque values ranged from 6.6 N.cm (RMO) to 10.2 N.cm (NEO). The characteristics that most influenced the results were outer diameter, inner diameter, the ratio between internal and external diameters, and the existence of milling in the apical region of the mini-implant. Conclusions: The fracture torques were different for both the neck and the tip of the five types evaluated. NEO and SIN mini-implants showed the highest resistance to fracture of the neck and tip. The fracture torques of both tip and neck were higher than the torque required to insert mini-implants