Midpalatal suture maturation in 15- to 35-year-olds: morphological assessment in the coronal plane using CBCT-an exploratory study.

Rapid maxillary expansion (RME) is used in patients presenting transverse maxillary deficiency. However, RME may be unpredictable after late adolescence if the midpalatal sutural maturation stage (MPMS) is in late stage. Since MPMS evaluation is influenced by the expertise of the operator and image quality, this classification method could be complemented. Therefore, this study aimed to analyze the morphology of the midpalatal suture (MPS) and its surrounding bone in the coronal plane using cone beam computed tomography (CBCT) images of adolescents and young adults and to correlate the findings with their respective MPMS status. CBCT scans of 200 patients aged 15-35 years of both sexes were evaluated. MPS and surrounding bone tissue characteristics in the coronal and axial sections were analyzed, and MPMS was evaluated (A to E). Six categories were identified for the coronal evaluation, analyzing it in 2 standardized locations. Sutural morphology: I, hypodense sutural line limited by 2 hyper-dense para-sutural lines; II, hypodense sutural line; and III, suture not visible. The presence of para-sutural cancellous bone: CB0, compact bone; CB1, dense cancellous tissue; CB2, spaced cancellous bone. Midpalatal bone thickness (MBTh) was also measured. ANOVA-Bonferroni, chi-square, logistic regression and t-tests were used. MPMS increased with age. Sutural morphology I and CB0 bone were the most prevalent. Here we show that sutural morphology, para-sutural bone characteristics, and MPSM were significantly associated. The coronal evaluation of the MPS can complement the information from the MPSM assessment, allowing the identification of patent MPS even in the presence of late MPSM.

Stability of first and second premolars extraction space closure.

INTRODUCTION: Premolars are the teeth most often extracted to provide space to correct crowding, excessive dental and/or labial protrusion, and to compensate for the sagittal discrepancy. After treatment, the extraction spaces have to remain closed. Nevertheless, several studies have shown a tendency for some relapse even in patients finished with an adequate occlusion. Thus, the objective of this study was to compare the stability of extraction space closure of the first and second premolars. METHODS: Dental casts of 72 patients were digitized using a 3-dimensional scanner (R700; 3Shape, Copenhagen, Denmark) and divided into 2 groups. Group 1 (29 patients; mean age, 13.79 years; 4.57 years after treatment; 116 extraction spaces) was treated with first premolar extractions, and group 2 (43 patients; mean age, 15.20 years; 3.97 years after treatment; 100 extraction spaces) was treated with second premolar extractions. Chi-square tests were used to compare the numbers of open and closed extraction spaces after treatment and at the long-term posttreatment stage. t Tests were used to compare the number of spaces posttreatment and at the long-term posttreatment stages. These tests were also performed in subgroups with completely closed extraction sites posttreatment. RESULTS: The groups showed similar numbers of extraction sites reopening. The first and second premolar extraction space closure presents a similar tendency for reopening. Considering only the patients that showed completely closed extraction spaces in the final dental models, maxillary extraction space reopening was larger in the first premolar extraction group. CONCLUSIONS: First and second premolar extraction space closure present similar stability.

Diagnostic assessment of tooth maturation of the mandibular second molars as a skeletal maturation indicator: A retrospective longitudinal study.

INTRODUCTION: Our aim was to analyze the correlation between growth status in height and chronological age, carpal maturation, cervical maturation, and dental maturation, and assess the diagnostic performance of Demirjian's dental maturation as an indicator of the pubertal growth spurt, through a retrospective longitudinal study. METHODS: Records of 60 Canadian patients obtained from the Burlington Growth Centre, which included height and weight charts and a set of x-rays at 6 points in time, were analyzed. The images at each point in time included 1 hand and wrist radiograph, a lateral cephalometric x-ray, and one 45° oblique cephalometric radiograph of each side, which were analyzed using the methods of Fishman, Baccetti, and Demirjian on the mandibular left and right second molars, respectively. The onset of the pubertal growth peak in height (distance to growth peak [DGP]) was identified, and the correlation between methods with DGP was assessed. RESULTS: High levels of correlation were obtained between the methods of Fishman, Baccetti, and Demirjian with DGP. The cutoff point between prepubertal and postpubertal stages was F stage for women and G stage for men, with statistically significant levels of sensitivity and specificity for the test. CONCLUSIONS: The use of the method of Demirjian applied to mandibular second molars is plausible as a predictor of the occurrence of the DGP for the studied population.

Morphological effects of mesenchymal stem cells and pulsed ultrasound on condylar growth in rats: a pilot study.

AIM: The aim of this study was to assess and describe the morphological effects of an intra-articular iniection of Mesenchymal Stem Cells (MSCs) and/or Low Intensity Pulsed Ultrasound (LIPUS) stimulation on the mandibular condyles of growing rats, using cone beam computed tomography (CBCT) and histology. METHODS: Twenty-six young (23-day-old) rats were divided into 5 groups identified as LIPUS-stimulated (20 minutes daily using 50 mW/cm2, 1MHz, 0.2 millisecond pulses), MSCs injected (1 x 10(5) cells/kg), LIPUS + MSCs, medium inlected, and untreated controls. All treatments were performed in the left temporomandibular joint of each rat (TMJs). At day 21, CBCTs were obtained for cephalometric analysis and 3D reconstructions. After animal sacrifice, left and right TMJ sections were histologically prepared and examined. The Wilcoxon sign rank test and the Kruskal-Wallis 2 test were applied for statistical comparison. RESULTS: Imaging results showed that left condyles were wider in all LIPUS-treated groups (p < 0.05), while the LIPUS-only group had a greater left sagittal condylar length. LIPUS-treated groups displayed a lower midline shift to the right (p < 0.02). No significant differences were observed in the MSC group. Bone marrow morphology and vascularity differed between the groups as LIPUS-treated groups exhibited increased vascularity in the erosive cartilage zone. CONCLUSION: It was established that LIPUS and MSC application to the TMJ region of growing rats favoured transverse condylar growth, while LIPUS application alone may enhance sagittal condylar development.The MSC injection model had little effect on sagittal condylar growth.

Comparison of the shear bond strength of new and recycled metallic brackets using different adhesive materials : an in vitro study.

Purpose: To evaluate and compare shear bond strength (SBS) of new and recycled metallic brackets bonded to conditioned and reconditioned enamel, using two different adhesive materials. Materials and methods: 72 extracted sound human premolars were randomly divided into 6 groups. Transbond XT light cured composite (LCC) and Fuji Ortho LC resin-modified glass ionomer (RMGI), were used as adhesive materials. In groups 1 and 2 (control), new brackets were bonded to sound premolars using either LCC or RMGI, respectively. In Groups 3 and 4, new brackets were bonded to reconditioned enamel; and in groups 5 and 6, sandblasted recycled brackets were rebonded to reconditioned enamel. After 5.000 thermal cycles between 5ºC and 55ºC, SBS was evaluated and adhesive remnant on the enamel assessed using the ARI index. Statistical analyses included Shapiro-Wilk, ANOVA, Fligner-Killeen ANOVA and Tukey tests. Results: The statistical analysis showed no significant difference in SBS comparing control and experimental groups for either new or recycled brackets (p = 0.848). The SBS was significantly higher in brackets bonded with LCC (15.7 MPa) than RMGI (11.6 MPa) (p = 0.006). Adhesive failure was the most frequent, with the adhesive remnant covering more than 50% of the bracket base. Conclusion: No significant differences were observed in SBS using either new or recycled brackets, regardless of the dental surface treatment (conditioned or reconditioned). Significantly higher SBS values were obtained with LCC adhesive. Adhesive failure prevails in all groups.

Use of automated artificial intelligence to predict the need for orthodontic extractions.

Objective: To develop and explore the usefulness of an artificial intelligence system for the prediction of the need for dental extractions during orthodontic treatments based on gender, model variables, and cephalometric records. Methods: The gender, model variables, and radiographic records of 214 patients were obtained from an anonymized data bank containing 314 cases treated by two experienced orthodontists. The data were processed using an automated machine learning software (Auto-WEKA) and used to predict the need for extractions. Results: By generating and comparing several prediction models, an accuracy of 93.9% was achieved for determining whether extraction is required or not based on the model and radiographic data. When only model variables were used, an accuracy of 87.4% was attained, whereas a 72.7% accuracy was achieved if only cephalometric information was used. Conclusions: The use of an automated machine learning system allows the generation of orthodontic extraction prediction models. The accuracy of the optimal extraction prediction models increases with the combination of model and cephalometric data for the analytical process.

Comparison of the primary stability of orthodontic miniscrews after repeated insertion cycles.

OBJECTIVES: To compare the primary stability of miniscrews after repeated cycles of insertion through insertion torque (IT) measurements and resonance frequency analysis (RFA). MATERIALS AND METHODS: Sixty titanium miniscrews were divided into two groups according to the insertion protocol: one with predrilled sites and the other self-drilled into porcine iliac crest bone specimens. Each group had three cycles of reinsertion. After each insertion, the IT and RFA were measured. The IT was measured by using a torque meter, and the RFA was measured using the Osstell ISQ device. A total of five miniscrews of each group were selected for sequential assessment of the morphology of their tip and threads using scanning electron microscopy after each insertion cycle. RESULTS: No statistically significant differences were found in the IT values of miniscrews reinserted up to three times in the group with predrilled surgical sites. The IT value increased significantly with the number of reinsertions in the self-drilled group. The RFA value decreased as the number of insertions increased in both groups. CONCLUSIONS: Under the conditions of this in vitro study, reinserting miniscrews deteriorates the integrity of their tip and thread. Reinsertion should be discouraged particularly when insertion sites are not predrilled.

Cephalometric radiographic comparison of alveolar bone height changes between adolescent and adult patients treated with premolar extractions: A retrospective study.

OBJECTIVE: In orthodontic treatment, indication of dental extractions is very common and frequently used in adult patients. This situation is a recurrent concern among orthodontists, since age and extraction treatment are factors that may increase periodontal support loss. Therefore, this study aimed to evaluate adolescent and adult patients, orthodontically treated with maxillary premolar extractions, and compare both groups regarding the changes in alveolar bone height loss, retrospectively. MATERIALS AND METHODS: Fifty-five patients were selected from the files of an Orthodontic Department and divided into 2 groups. The adolescent group comprised 30 patients with a mean age of 12.7 years (SD=1.4) and the adult group comprised 25 patients with a mean age of 25.0 years (SD=1.8). Periapical radiographs obtained at pre-treatment (T1) and posttreatment (T2) were evaluated. Wilcoxon tests were used to analyse intragroup treatment changes. Mann-Whitney tests were used to compare intergroup and inter-sex initial and final statuses and treatment changes. P<0.05 is considered to be statistically significant. RESULTS: Statistically significant increases in alveolar bone height loss of the maxillary central incisors were observed on the right and left sides of the adolescent (P=0.001 and P=0.002, respectively) and of the adult (P=0.001 and P<0.001, respectively) groups, during treatment. There were no significant differences in alveolar bone height between initial and final state, in treatment effects between adolescent and adult patients, in extraction patterns, and between males and females. CONCLUSIONS: Significant increase in alveolar bone height loss was found in both adult and adolescent patients orthodontically treated with maxillary premolar extractions. However, no significant differences were found regarding alveolar bone height changes after extraction orthodontic treatment between adolescent and adult patients.

Low-intensity pulsed ultrasound stimulation of condylar growth in rats.

OBJECTIVE: To test the hypothesis that low-intensity pulsed ultrasound (LIPUS) stimulation does not histologically affect the growth of mandibular condylar cartilage. MATERIALS AND METHODS: Thirty-five 20-day-old Sprague-Dawley rats were assigned to experimental and control groups. Experimental rats were stimulated with LIPUS in the temporomandibular joint (TMJ) region unilaterally, for 10 or 20 minutes for 20 days. After euthanasia, histological specimens were analyzed qualitatively and histomorphometrically at the anterior and posterior aspects of the mandibular condyle, including the condylar cartilage and the area and perimeter of subchondral bony trabeculae. RESULTS: LIPUS stimulation may alter the histological arrangement of the condylar bone and cartilage, showing qualitative differences on specimens treated for 10 or 20 minutes daily compared with controls. Cartilaginous layer thickness was not affected by LIPUS stimulation to a significant level, but was modified at the relative layer thickness within the cartilage at the anterior aspect of the condyle (P < .05). At the subchondral bone level, 20-minute stimulation significantly increases trabecular perimeter (P = .01). CONCLUSIONS: LIPUS application may affect mandibular growth pattern in rats acting at the cartilage and bone level. The effect of LIPUS on the growing condyle is expressed through a variation in trabecular shape and perimeter. A greater response is achieved when stimulated for 20 minutes instead of 10 minutes daily.

Cephalometric Characteristics in Chilean Latino Population with Normal Occlusion and Harmonic Profiles in Permanent Dentition. A Retrospective Study / Características Cefalométricas en Población Latina Chilena con Oclusión Normal y Perfiles Armónicos en Dentición Permanente. Un Estudio Retrospectivo

SUMMARY: Malocclusion is usually treated based on clinical decisions complemented with a cephalometric analysis, allowing the comparison of an individual with standard reference norms. Cephalometric standards have mostly been obtained from Caucasian population, but may not be appropriate for other ethnic groups, becoming a clinically relevant problem in multicultural and multiracial societies. The present study aimed to establish cephalometric norms for Chilean-Latino population, using a representative sample of class I individuals in permanent dentition. A sample of 72 cephalometric x-rays of class I growing individuals (47 women and 25 men) between 10 and 20 years of age with class I occlusion and harmonic profile was obtained from the records of the Universidad de los Andes taken between 2012 and 2019, including 1164 individuals. The radiographs were classified according to their cervical vertebral maturation status, and cephalometrically analyzed, obtaining vertical and sagittal parameters in soft and hard tissues, which were compared with Caucasian cephalometric norms. The statistical analysis was performed using descriptive and inferential statistics (T-test, ANOVA and Bonferroni tests). Cephalometric norms were obtained for hard and soft tissues. Upon comparison with Caucasian norms, the subjects included in the sample present a tendency towards a convex profile, significant incisal proclination, dental protrusion, labial biprotrusion and an acute nasolabial angle. There are cephalometric differences between the Caucasian cephalometric norms and those observed Chilean Latino population, displaying differences at a hard and soft tissue level that should be taken into account for clinical decision making in Orthodontics.

La maloclusión generalmente se trata con base en decisiones clínicas complementadas con un análisis cefalométrico, lo que permite la comparación de un individuo con normas de referencia estándar. Los estándares cefalométricos se han obtenido en su mayoría de población caucásica, pero pueden no ser apropiados para otros grupos étnicos, convirtiéndose en un problema clínicamente relevante en sociedades multiculturales y multirraciales. El presente estudio tuvo como objetivo establecer normas cefalométricas para población chileno-latina, utilizando una muestra representativa de individuos clase I en dentición permanente. Se obtuvo una muestra de 72 radiografías cefalométricas de individuos en crecimiento clase I (47 mujeres y 25 hombres) entre 10 y 20 años de edad con oclusión clase I y perfil armónico de los registros de la Universidad de los Andes tomados entre 2012 y 2019, incluidas 1164 personas. Las radiografías se clasificaron según su estado de maduración vertebral cervical, y se analizaron cefalométricamente, obteniendo parámetros verticales y sagitales en tejidos blandos y duros, que se compararon con normas cefalométricas caucásicas. El análisis estadístico se realizó mediante estadística descriptiva e inferencial (T-test, ANOVA y pruebas de Bonferroni). Se obtuvieron normas cefalométricas para tejidos duros y blandos. En comparación con las normas caucásicas, los sujetos incluidos en la muestra presentan una tendencia hacia un perfil convexo, proinclinación incisal significativa, protrusión dental, biprotrusión labial y un ángulo nasolabial agudo. Existen diferencias entre las normas cefalométricas caucásicas y las observadas en población latina chilena, mostrando diferencias a nivel de tejidos duros y blandos que se deben considerar para la toma de decisiones clínicas en Ortodoncia.

Threaded versus porous-surfaced implants as anchorage units for orthodontic treatment: three-dimensional finite element analysis of peri-implant bone tissue stresses.

PURPOSE: A 3-dimensional finite element model was developed to investigate the cause of different crestal bone loss patterns observed around sintered porous-surfaced and machined (turned) threaded dental implants used for orthodontic anchorage in a previously reported animal study. MATERIALS AND METHODS: Twenty-noded structural solid elements with parabolic interpolation between nodes were used for modeling the bone-implant interface zone. A 3-N traction force acting between either 2 porous-surfaced or 2 machined threaded implants placed in canine premolar mandibular sites and bone profiles observed at initiation and 22 weeks of orthodontic loading were modeled. RESULTS: Higher maximum stresses in peri-implant bone next to the coronal region of the implants were predicted with the machined threaded implants at both the initial and final time points, with the values 20% greater than those predicted after the 22-week loading period. These values were approximately 200% greater than those predicted for the porous-surfaced implants, for which a more uniform stress distribution was predicted. DISCUSSION: The finite element model results indicated that the observed greater retention of crestal bone next to the porous-surfaced implants was attributable to lower peak stresses developing in crestal peri-implant bone with this design, which decreased the probability of bone loss related to local overstressing and bone microfracture. CONCLUSION: The predicted lower stresses were a result of the more uniform transfer of force from implant to bone with the porous-surfaced implants, which was a consequence of the interlocking of bone and implant possible with this design.

Apnea Obstructiva del Sueño y el Rol del Ortodoncista. Revisión bibliográfica / Obstructive Sleep Apnea and the Role of the Orthodontist. Bibliographical review

RESUMEN: Introducción: La apnea obstructiva del sueño es un trastorno crónico, altamente prevalente, asociada a secuelas cardiovasculares y neurocognitivas, que afectan gravemente la calidad de vida de los individuos que la padecen. En aquel contexto, tanto el odontólogo general, como especialista, tienen un rol importante en el screening y potencial tratamiento interdisciplinario de esta patología. Revisión de la literatura actual: Se describen las causas y las secuelas asociadas a este trastorno, junto con los métodos de screening inicial que sirven para una derivación oportuna. Además, se plantean las alternativas de tratamiento y la evidencia actual disponible sobre sus efectos terapéuticos. Discusión y conclusión: Por ser la apnea obstructiva del sueño una patología compleja y de origen multifactorial, se aborda con un equipo interdisciplinario para determinar la mejor estrategia de tratamiento de acuerdo a las características de cada paciente, y entendiendo las repercusiones que cada terapia conlleva. En Ortodoncia, existen controversias respecto del efecto de los tratamientos con extracciones de premolares sobre las dimensiones de la vía aérea superior, donde es relevante analizar críticamente la evidencia científica disponible al respecto, y con ello, asegurar estrategias óptimas de tratamiento en la práctica clínica.

ABSTRACT: Introduction: Obstructive sleep apnea is a chronic, highly prevalent disorder associated with cardiovascular and neurocognitive repercussions, which seriously affect the quality of life of the individuals who suffer from it. In that context, both the general dentist and the specialist have an important role in the screening and potential interdisciplinary treatment of this disorder. Review of current literature: The causes and sequelae associated with this disorder are described, together with the initial screening methods that serve for a timely referral. In addition, treatment alternatives and current available evidence on their therapeutic effects are addressed. Discussion and conclusion: Since obstructive sleep apnea is a complex and multifactorial disorder, it is approached from an interdisciplinary perspective to determine the best treatment strategy according to the characteristics of the patient, with a clear understanding of the repercussions that each therapy involves. In Orthodontics, controversy exist about the effect of treatment with premolar extractions on the dimensions of the upper airway. It is relevant to critically analyze the available evidence about this controversy in order to ensure optimal treatment strategies in clinical practice.

Análisis comparativo in vitro de la resistencia adhesiva al cizallamiento de brackets metálicos adheridos a superficies dentarias tratadas con diferentes agentes blanqueadores / Comparative in vitro analysis of the adhesive resistance to the shear bond strength of metal brackets adhered to dental surfaces treated with different bleaching agents

RESUMEN: Objetivo: Evaluar y comparar el efecto de tres agentes blanqueadores en la resistencia adhesiva al cizallamiento de brackets metálicos. Método: Se cementaron 76 brackets en premolares humanos extraídos por indicación de ortodoncia. Se establecieron 4 grupos: (0) control, (1) esmalte tratado con Peróxido de Carbamida al 16%, (2) Peróxido de Hidrógeno al 35% y (3) tiras de blanqueamiento con Peróxido de Hidrógeno al 10%. Los brackets fueron cementados con Transbond XT (3M Unitek, EE.UU.). Se realizaron 5.000 ciclos de termociclado, luego se evaluó la resistencia adhesiva mediante una máquina Bisco y la cantidad de material adhesivo remanente según el índice adhesivo remanente (ARI). El análisis estadístico incluyó pruebas de Shapiro- Wilk, Kruskal -Wallis y Mann-Whitney. Resultados: Los grupos 0, 1, 2, 3 obtuvieron fuerzas de resistencia de 12.64, 11.06, 6.4 y 9.34 Mpa respectivamente con diferencia estadística entre los grupos (p <0.05). El ARI fue significativamente diferente en algunos grupos (p <0.05), indicando fallas adhesivas para el grupo 2 (p <0.05), cohesivas para el grupo control y de ambos tipos para los grupos 1 y 3. Conclusiones: El peróxido de hidrógeno al 35% reduce la resistencia adhesiva al cizallamiento en brackets metálicos sometidos a termociclado 24 horas luego del blanqueamiento.

ABSTRACT: Aim: To evaluate and compare the effect of three bleaching agents on the shear bond strength of metallic brackets. Method: Brackets were cemented on 76 human premolars extracted for orthodontic reasons. 4 groups were evaluated: (0) Control, (1) enamel treated with Carbamide Peroxide 16%, (2) Hydrogen Peroxide 35% and (3) Hydrogen Peroxide 10% "Whitening strips". All brackets were cemented using Transbond XT adhesive system (3M, Unitek, USA). All samples were thermocycled (5.000 cycles). Shear bond strength was evaluated with a Bisco machine and the amount of adhesive material at the base of the brackets and enamel surface was assessed using the adhesive remnant index (ARI). The statistical analysis included Shapiro-Wilk, Kruskal-Wallis and Mann-Whitney U tests. Results: The results of shear bond strength for groups 0, 1, 2, and 3 were 12.64, 11.06, 6.4 and 9.34 MPa respectively, with statistically significant differences between groups (p <0.05). ARI index was significantly different in some groups (p <0.05), indicating cohesive failure for control, adhesive failure for group 2 (p <0.05), adhesive and cohesive failure for groups 1 and 3. Conclusions: The 35% hydrogen peroxide office bleaching agent reduces adhesion values in the metal brackets thermocycled 24 hours after bleaching.

Maduración de la Sutura Palatina Media En Adolescentes y Adultos Jóvenes Chilenos: Estudio Transversal / Midpalatal Sutural Maturation in Chilean Adolescents and Young Adults: Cross-sectional Study

RESUMEN: Objetivo: Evaluar la maduración de la sutura palatina media en adolescentes y adultos jóvenes chilenos, mediante valoración morfológica de imágenes de tomografía computarizada de haz cónico del maxilar. Material y método: Se analizó la sutura palatina media de 150 sujetos entre 15 y 30 años, seleccionados desde la base de datos radiológicos de un centro universitario de salud. La maduración sutural fue evaluada en el corte axial, utilizando el método de Angelieri y cols., clasificándola en cinco etapas (A, B, C, D y E). Se utilizaron las pruebas de correlación de Pearson para medir la concordancia intra e interexaminador, y T-Student para las diferencias entre sexos. Resultados: El estado de maduración más frecuente fue C (43,3%), seguido por E (33,3%) y D (22%). En hombres, la etapa C fue más frecuente (49%), mientras que en mujeres fue la etapa E (39%). Sin embargo, no se encontraron diferencias estadísticamente significativas entre ambos sexos. Conclusiones: Aunque la mayoría de la muestra presentó una etapa tardía de maduración sutural, el 45% presentó estados de maduración sutural donde sería posible la expansión de naturaleza no quirúrgica. Debido a la variabilidad observada en adolescentes y adultos jóvenes, se recomienda la evaluación individual con imagenología 3D.

ABSTRACT: Objective: To evaluate midpalatal suture maturation in Chilean adolescents and young adults through morphological assessment of cone-beam computed tomography images of the maxilla. Materials and methods: Analysis of the midpalatal suture of 150 subjects aged between 15 and 30 was performed, selected from a university clinical center radiological database. Sutural maturation was evaluated in the axial cross-section, using the method described by Angelieri et al., classifying it in five stages (A, B, C, D and E). Pearson's correlation tests were used to assess intra- and inter-examiner agreement, and T-Student for assessing differences between genders. Results: The most frequent maturation stage was C (43.3%), followed by E (33.3%) and D (22%). In men, stage C was more frequent (49%), while in women it was stage E (39%). However, no statistically significant differences were found between genders. Conclusions: Although the majority of the sample presented a late stage of sutural maturation, 45% presented states of sutural maturation where the expansion of a non-surgical nature would be possible. Due to the variability observed in adolescents and young adults, individual evaluation with 3D imaging is recommended.

Peri-implant bone response to orthodontic loading: Part 1. A histomorphometric study of the effects of implant surface design.

INTRODUCTION: Bone response to orthodontic loading was compared histomorphometrically around 2 different types of osseointegrated implants (porous surfaced and machined threaded) to determine their suitability for orthodontic anchorage. METHODS: Five beagles each received 3 implants of each design in contralateral mandibular locations. After a 6-week initial healing period, abutments were placed, and, 1 week later, the 2 mesial implants on each side were orthodontically loaded for 22 weeks. All implants remained osseointegrated throughout orthodontic loading except for 1 threaded implant that loosened. Light miscroscopy and back-scattered scanning electron microscopy were used to compare responses around the 2 implant designs. RESULTS: Porous-surfaced implants had higher marginal bone levels (P +/- .025) and less relative implant displacement than threaded implants. CONCLUSIONS: Differences in implant surface design can lead to differences in peri-implant bone height and bone-to-implant contact. Porous-surfaced implants might be successful as orthodontic anchorage units.

Peri-implant bone response to orthodontic loading: Part 2. Implant surface geometry and its effect on regional bone remodeling.

INTRODUCTION: Bone response to orthodontic loading was compared around 2 different types of osseointegrated implants (porous surfaced and machined threaded) to determine the effect of implant surface geometry on regional bone remodeling. METHODS: Five beagles each received 3 implants of each design in contralateral mandibular extraction sites. After a 6-week initial healing period, abutments were placed, and, 1 week later, the 2 mesial implants on each side were orthodontically loaded for 22 weeks. All implants remained osseointegrated throughout orthodontic loading except for 1 threaded implant that loosened. Back-scattered scanning electron microscopy and fluorochrome bone labeling techniques were used to compare responses around the 2 types of implants. RESULTS: The loaded, porous-surfaced implants had significantly higher marginal bone levels and greater bone-to-implant contact than did the machined-threaded implants. CONCLUSIONS: Significant differences in peri-implant bone remodeling and bone formation in response to controlled orthodontic loading were observed for the 2 implant designs. Short, porous-surfaced implants might be more effective for orthodontic applications than machine-threaded implants.

Sistema de braquetes autoligáveis: a grande tendência na ortodontia moderna / Self-ligating brackets system: the great tendency on contemporary orthodontics

O presente artigo apresenta considerações gerais sobre os sistemas de braquetes autoligáveis, com ênfase ao aparelho Speed. A literatura relata que a fricção gerada entre o braquete e o fio é principalmente determinada pela natureza da ligação, ou seja, elástico, presilha ou amarrilho metálico. Dessa forma, cada vez mais, os braquetes autoligáveis têm despertado o interesse dos ortodontistas, uma vez que nesse sistema a atividade friccional é consideravelmente reduzida e a liberação de forças mais leves é possibilitada, facilitando assim o movimento dentário. Além disso, o tempo de tratamento é reduzido e o conforto ao paciente é otimizado. Dentre os sistemas mais conhecidos podemos citar o Speed (Strite Industries), o Damon (Ormco), o In-Ovation-R (GAC International) e o Smart Clip (3M Unitek). Também será apresentado um caso clínico que foi tratado com o sistema de braquetes autoligáveis Speed.

Epidemiología de las fracturas mandibulares en pacientes del área metropolitana occidente / Epidemiology of mandibular fractures in the patients of the west metropolitan area

Se presenta un estudio retrospectivo a 5 años (Enero de 1991 a Julio 1996) sobre 89 pacientes con fracturas mandibulares tratados en el Hospital San Juan de Dios, donde fueron consideradas las siguientes variables: Edad, Sexo, Ubicación anatómica, Etiología, Número de Rasgos. Se estudió la prevalencia de fractura de Cóndilo con respecto al grupo de las fracturas mandibulares, la prevalencia individual de cada una de ellas, y los elementos epidemiológicos que se presentan en este tipo de patologías. Los resultados demostraron que la fractura mandibular más prevalente fue la Paramediana, seguida en frecuencia por la del Angulo y luego por la del Cóndilo Mandibular. Se determinó además la proporción de fractura por mandibula es de 1:1,49, lo que indica que términos generales la probabilidad de que una mandibula fracturada presente otro rasgo de fractura bordea el 50 por ciento. El factor etiológico más frecuentes fueron los asaltos y violencia física (67,4 por ciento), seguidas por las caídas y luego por accidentes de tránsito.