BACKGROUND: The temporary anchorage devices (TAD) rely on mechanical retention to achieve their function. Following dental implants, the design has not been thoroughly studied. Most of the TADs available in the market are either conical or cylindrical homogenous designs. This study aims to evaluate whether a non-homogeneous design would be able to achieve better biomechanical properties than the current mini- screw designs available on the market. MATERIAL AND METHODS: This is a preliminary study comparing two different 1.5mm TAD designs, the Spider Screw® (Ortho Technology®), and one experimental TAD, the Novel TAD Design (NTD). The two TAD designs were generally described and evaluated following the ANSI/ADA Standard No. 178, then the core diameter / TAD diameter ratio was calculated at 0, 2, 4, and 6mm using the Mitutoyo PH-3500 projection machine in combination with QM-data 200. 10 TADs from each design were inserted in a 30 PCF laminated block from SAW Bone under a 12N axial load, using the Instron 5566A to measure the insertion torques and removal torques. Torque ratios were then calculated. Using the same Instron machine with TADs fully inserted in the artificial bone (2 per design per angle), pull-out tests were performed at angles of 0° / 30° / 60° / 90°. The TADs were loaded up to failure. One-way ANOVA and student's t-test were used for statistical analysis. RESULTS: The Spider Screw® is a conical, self-drilling, self-tapping design with the following general dimensions (d1: 1.5mm ; d2: 0.5mm; d3: 3.4mm; k1: 1mm; k2: 2mm; L1: 9.5mm; L2: 6.5mm; L3: 6.2mm), a 0.6mm pitch, 0.3mm thread depth, asymmetrical triangular threads. NTD, it is a cylindrical-conical, self-tapping design with the following general dimensions (d1: 1.5mm; d2: 0.85mm; d3: 2.5mm; k1: 1mm; k2: 2mm; L1: 9mm; L2: 6mm; L3: 6mm), a 0.5mm pitch, double threads in the first 2mm, a variable thread depth (0-2mm: 0.2mm ; 3-5mm: 0.35mm) and symmetrical rectangular threads. The core to width ratios for the Spider Screw® and NTD were respectively 1 ; 0.64 ; 0.61; 0.54 and 0.7; 0.53; 0.56 and 0.58. Mean insertion torque, removal torque and torque ratio for the Spider Screw and the NTD were respectively (12.78 N.cm / 11.32 N.cm, 0.90 ; 12.73 N.cm / 12.65 N.cm, 0.99 ) Mean pull-out forces at 0°/30°/60° and 90° for the Spider Screw® and the NTD were respectively 124.18 N / 108.59 N / 69.67 N / 84.75 N and 137.72 N / 109.7 N / 64.96 N / 66.78 N. There were no statistically significant differences found. CONCLUSIONS: After evaluating both of the TADs, it is clear that the designs are relatively different. The NTD showed to have a higher torque ratio, and therefore it could mean that the design would be clinically more effective. The NTD showed to perform as good or even slightly better than the Spider Screw® design, but a larger variety of TAD designs is needed to be able to confirm the conclusions of this study. / 2023-03-02T00:00:00Z

Background: Maxillary expansion has long been used in children and adolescents for transverse discrepancies and dental crowding. With age, the mid-palatal suture becomes increasingly mature, requiring heavy, rapid force in order to achieve skeletal expansion. As an individual grows into adulthood, it has been demonstrated that a skeletally anchored expander can be used in order to achieve successful sutural separation. The side effects between these two types of expanders, including dental tipping with relative extrusion of buccal segments and clockwise mandibular rotation, have been demonstrated to have differences in their degrees of severity. However, most of the studies have evaluated the effects immediately following the expansion and not through a prolonged period in which growth may occur. The purpose of the present study was to investigate long-term skeletal differences in two types of expansion (RPE vs MARPE) on a growing population. Methods: This retrospective study included 39 adolescent subjects (mean age = 13.8 years) who had received maxillary expansion (20 RPE, 19 MARPE) with subsequent completion of orthodontic treatment. Initial and final CBCTs were used to analyze cephalometric and transversal changes between the two groups. Transverse measurements were repeated two weeks apart to test intra-observer reliability. Results: Cephalometric analysis demonstrated no significant differences in changes of FMA (p = 0.549) or MP-SN (p = 0.722) between the two groups following expansion and completion of orthodontic treatment. There were statistically significant differences in transverse changes between the two groups, with the MARPE group displaying more skeletal expansion. Conclusions: The results of the present study suggest that skeletally anchored expander - MARPE and conventional expander have similar skeletal effects in adolescents.

Com o objetivo de avaliar a influência do processo de cicatrização óssea sobre o desempenho biomecânico de mini-parafusos utilizados como ancoragem em ortodontia, foram inseridos 60 mini-parafusos (1,6 x 6mm) auto-rosqueantes (Tomas® Dentaurum / Germany) na maxila e na mandíbula de 5 cães adultos da Raça Beagle. Os pré-molares (P1, P2, P3, P4) superiores e inferiores foram extraídos três meses antes da inserção vertical dos mini-parafusos. Os cães foram sacrificados nos dias 0, 2, 7, 15 e 30 após a instalação dos mini-parafusos. Os maxilares foram dissecados e os corpos de provas contendo os mini-parafusos foram preparados para avaliação da resistência à tração na Máquina de Ensaios Universal EMIC® 2000, utilizando uma garra desenvolvida especificamente para este estudo. Os valores e gráficos correspondentes ao desempenho mecânico foram imediatamente gerados e registrados pelo programa de aquisição Tesc 3.01®. As possíveis diferenças entre os períodos de cicatrização foram avaliadas pela análise de variância (ANOVA) e pelo teste de comparações múltiplas de Bonferroni. Os resultados demonstraram um índice de sucesso de 100% dos mini-parafusos inseridos. Após a dissecação dos segmentos ósseos, verificou-se que em alguns casos a superfície da rosca ficou parcialmente exposta, razão pela qual o cálculo da resistência à tração (média na maxila de: 141,76 ± 92,82 Ncm a 237,02 ± 78,34 Ncm e média na mandíbula de: 156,86 ± 75,55 Ncm a 328,76 ± 82,17 Ncm) foi feito em relação à área real de inserção (maxila: 24,01 ± 6,09mm2 e mandíbula: 22,88 ± 5,31mm2), observando-se um valor médio por mm2 significativamente maior na mandíbula (11,60 ± 5,22 Ncm) quando comparado à maxila (8,22 ± 5,04 Ncm). A relação entre a intensidade da força de tração (Ncm), superfície inserida (mm2) e períodos de cicatrização não apresentaram diferenças significantes (p= 0,126). Com base nestes resultados podemos concluir que os mini-parafusos avaliados demonstraram excelente desempenho biomecânico nos diferentes períodos de cicatrização analisados, apresentando maior resistência à tração no osso mandibular. / With the purpose of evaluating the influence of bone healing process on the biomechanical performance of mini-screws used as anchorage in orthodontics, 60 self-tapping (Tomas® - Dentaurum / Germany) mini-screws were inserted (1.6 x 6 mm) in the maxilla and in the mandible of 5 adult Beagle dogs. Upper and lower premolars (P1, P2, P3, P4) were extracted three months before the vertical insertion of mini-screws. The dogs were sacrified on days 0, 2, 7, 15 and 30 after the insertion of mini-screws. The jaws were dissected and the bone blocks, containing the miniscrews, were prepared to the axial pull-out strength in the Universal Testing Machine EMIC ® 2000, using a device developed specifically for this study. The values and graphics for the mechanical performance were immediately generated and recorded by the acquisition program. The clinical success rate of mini-screws was 100%. The possible differences between the healing periods were analyzed by Bonferroni´s multiple test comparisons and variance analysis (ANOVA). After the dissection of the bone segments, it was found that in some cases, the mini-screw thread was not fully inserted into the bone, reason why the pull-out strength (average of the maxilla: 141.76 ± 92.82 Ncm to 237.02 ± 78.34 Ncm and average in the mandible of 156.86 ± 75.55 Ncm to 328.76 ± 82.17 Ncm) was evaluated in relation to the real area of insertion (maxilla: 24.01 ± 6.09 mm2 and mandible: 22.88 ± 5.31 mm2). Mean value/mm2 were significantly higher in the mandible (11.60 ± 5.22 Ncm/mm2) than the maxilla (8.22 ± 5.04 Ncm/mm2). There was no statistically significant difference (p = 0126) between pull-out strength (Ncm), surface inserted (mm2) and the observed healing periods. Based on these results it can be concluded that mini-screws evaluated in this study demonstrated an excellent biomechanical behavior in all different periods of healing, showing more resistance to traction in the mandibular bone.

Com o objetivo de avaliar a influência do processo de cicatrização óssea sobre o desempenho biomecânico de mini-parafusos utilizados como ancoragem em ortodontia, foram inseridos 60 mini-parafusos (1,6 x 6mm) auto-rosqueantes (Tomas® Dentaurum / Germany) na maxila e na mandíbula de 5 cães adultos da Raça Beagle. Os pré-molares (P1, P2, P3, P4) superiores e inferiores foram extraídos três meses antes da inserção vertical dos mini-parafusos. Os cães foram sacrificados nos dias 0, 2, 7, 15 e 30 após a instalação dos mini-parafusos. Os maxilares foram dissecados e os corpos de provas contendo os mini-parafusos foram preparados para avaliação da resistência à tração na Máquina de Ensaios Universal EMIC® 2000, utilizando uma garra desenvolvida especificamente para este estudo. Os valores e gráficos correspondentes ao desempenho mecânico foram imediatamente gerados e registrados pelo programa de aquisição Tesc 3.01®. As possíveis diferenças entre os períodos de cicatrização foram avaliadas pela análise de variância (ANOVA) e pelo teste de comparações múltiplas de Bonferroni. Os resultados demonstraram um índice de sucesso de 100% dos mini-parafusos inseridos. Após a dissecação dos segmentos ósseos, verificou-se que em alguns casos a superfície da rosca ficou parcialmente exposta, razão pela qual o cálculo da resistência à tração (média na maxila de: 141,76 ± 92,82 Ncm a 237,02 ± 78,34 Ncm e média na mandíbula de: 156,86 ± 75,55 Ncm a 328,76 ± 82,17 Ncm) foi feito em relação à área real de inserção (maxila: 24,01 ± 6,09mm2 e mandíbula: 22,88 ± 5,31mm2), observando-se um valor médio por mm2 significativamente maior na mandíbula (11,60 ± 5,22 Ncm) quando comparado à maxila (8,22 ± 5,04 Ncm). A relação entre a intensidade da força de tração (Ncm), superfície inserida (mm2) e períodos de cicatrização não apresentaram diferenças significantes (p= 0,126). Com base nestes resultados podemos concluir que os mini-parafusos avaliados demonstraram excelente desempenho biomecânico nos diferentes períodos de cicatrização analisados, apresentando maior resistência à tração no osso mandibular. / With the purpose of evaluating the influence of bone healing process on the biomechanical performance of mini-screws used as anchorage in orthodontics, 60 self-tapping (Tomas® - Dentaurum / Germany) mini-screws were inserted (1.6 x 6 mm) in the maxilla and in the mandible of 5 adult Beagle dogs. Upper and lower premolars (P1, P2, P3, P4) were extracted three months before the vertical insertion of mini-screws. The dogs were sacrified on days 0, 2, 7, 15 and 30 after the insertion of mini-screws. The jaws were dissected and the bone blocks, containing the miniscrews, were prepared to the axial pull-out strength in the Universal Testing Machine EMIC ® 2000, using a device developed specifically for this study. The values and graphics for the mechanical performance were immediately generated and recorded by the acquisition program. The clinical success rate of mini-screws was 100%. The possible differences between the healing periods were analyzed by Bonferroni´s multiple test comparisons and variance analysis (ANOVA). After the dissection of the bone segments, it was found that in some cases, the mini-screw thread was not fully inserted into the bone, reason why the pull-out strength (average of the maxilla: 141.76 ± 92.82 Ncm to 237.02 ± 78.34 Ncm and average in the mandible of 156.86 ± 75.55 Ncm to 328.76 ± 82.17 Ncm) was evaluated in relation to the real area of insertion (maxilla: 24.01 ± 6.09 mm2 and mandible: 22.88 ± 5.31 mm2). Mean value/mm2 were significantly higher in the mandible (11.60 ± 5.22 Ncm/mm2) than the maxilla (8.22 ± 5.04 Ncm/mm2). There was no statistically significant difference (p = 0126) between pull-out strength (Ncm), surface inserted (mm2) and the observed healing periods. Based on these results it can be concluded that mini-screws evaluated in this study demonstrated an excellent biomechanical behavior in all different periods of healing, showing more resistance to traction in the mandibular bone.

Background and objectives: The control of anchorage is integral to successful orthodontic treatment. The objective of this research was to undertake three related projects to evaluate methods of increasing anchorage with the aim of adding to orthodontic knowledge and improve methods of treatment delivery. Methods: Two Cochrane systematic reviews were undertaken according to the methods published in the Cochrane Handbook for Systematic Reviews of Interventions, version 5.1.0. The influence of functional appliances on tooth position and the extraction decision was performed as a retrospective study using participants from a completed multicentre randomized trial. Results: 1- Statistically and clinically significant differences were found between the mean values of distal molar movement when surgical anchorage and conventional anchorage were compared. 2- Statistically significant differences were found between the mean values of distal molar movement and mesial upper incisor movement when intraoral distalising appliances and cervical headgear were compared.3- Fixed and removable functional appliances are equally effective in anchorage preparation. The type of functional appliance and time spent in Phase I treatment influenced the amount of lower incisor proclination. Conclusions: 1- Surgical anchorage is more effective than headgear without the inherent risks and compliance issues. However, intraoral appliances used in adolescence for distalisation of upper molars do not appear to have any advantages over cervical headgear. 2- Functional appliances reduce the anchorage requirements of a case primarily by reduction of the overjet, both fixed and removable functional appliances are equally effective in obtaining this. However, fixed functional appliances result in greater lower incisor proclination than removable functional appliances. 3- The type of functional appliance (removable or fixed) does not influence the extraction decision, however, this is influenced by overall space requirements.