Insertion torque, pull-out strength and cortical bone thickness in contact with orthodontic mini-implants at different insertion angles.

This study aimed to evaluate biomechanical behaviour of inclined orthodontic mini-implants by analyzing its insertion torque (IT), axial pull-out strength (APS), and cortical bone thickness in contact with mini-implant (CBTC). A total of 102 mini-implants were inserted at 90 degree, 60 degree, and 45 degree to the surface of synthetic bone. Peak IT was measured, and the mini-implants were aligned with the mechanical testing machine to record the APS. The cortical bone thickness in contact with each mini-implant was measured after the pull-out test and the data were subjected to statistical analyses. The 45 degree group had a significantly higher IT compared with the 90 degree group (P < 0.05). There was a statistically significant increase in the average of cortical bone thickness in CBTC across the three groups (P < 0.05). A negative correlation between the angulation and the CBTC (r = -0.95, P < 0.05) and a positive correlation between the APS and the CBTC were observed (r = 0.34, P < 0.05). Mini-implants that are inserted more inclined to the surface of the bone provide greater IT and an increased contact with the cortical bone. The greater the CBTC, the greater is the APS.

Digital signature of electronic dental records.

INTRODUCTION: The purpose of this article is to examine the feasibility of digital signature technology to guarantee the legal validation of electronic dental records. METHODS: The possible uses of digital signature technology, the actual use of digital signature technology to authenticate electronic dental records, the authentication of each part of the electronic dental record, the general legal principles involved, how to digitally sign electronic dental record files, and the limitations of this method are discussed. RESULTS AND CONCLUSIONS: It is possible to obtain electronic dental records that carry the same legal certainty as conventional, nonelectronic records. For this purpose, each part of the electronic dental records should be digitally signed by the author of the document.

Biodegradation of orthodontic metallic brackets and associated implications for friction.

INTRODUCTION: This study aimed to assess the effect of clinical exposure on the surface morphology, dimensions, and frictional behavior of metallic orthodontic brackets. METHODS: Ninety-five brackets, of 3 commercial brands, were retrieved from patients who had finished orthodontic treatment. As-received brackets, matched by type and brand, were used for comparisons. Surface morphology and precipitated material were analyzed by optical and scanning electron microscopy and x-ray microanalysis. Bracket dimensions were measured with a measuring microscope. Resistance to sliding on a stainless steel wire was assessed. RESULTS: Retrieved brackets showed surface alterations from corrosion, wear, and plastic deformation, especially in the external slot edges. Film deposition over the alloy surface was observed to a variable extent. The main elements in the film were carbon, oxygen, calcium, and phosphorus. The as-received brackets showed differences (P <0.05) in the slot sizes among brands, and 1 brand showed a 3% increase in the retrieved brackets' slots. The frictional behavior differed among brands. Retrieved brackets of 2 brands showed 10% to 20% increases in resistance to sliding. CONCLUSIONS: Metallic brackets undergo significant degradation during orthodontic treatment, possibly with increased friction. At present, it is difficult to predict the impact of these changes on the clinical performance of orthodontic components.

Treatment of an adult with several missing teeth and atrophic old mandibular first molar extraction sites.

This report describes the orthodontic treatment of a woman, aged 34 years 2 months, with several missing teeth and atrophic mandibular first molar extraction sites. We had planned to close the spaces from the missing maxillary canines with mesial movement of the premolars and molars. In the mandibular arch, protraction of the second molars into first molar extraction sites and reduction of the mandibular incisor protrusion were performed. No miniscrews or bone plates were used. A modified helical loop was used, and it can be considered a simple and an efficient orthodontic method of closing the spaces without mesial or lingual tipping and rotation. Pleasing esthetic and functional results were achieved.

Orthodontic-prosthetic treatment of an adult with a severe Class III malocclusion.

This case report describes the treatment of a 37-year-old woman with multiple restored and missing teeth, a Class III subdivision malocclusion, and complete dental crossbite. Treatment options included orthognathic surgery and an orthodontic-prosthetic approach. The patient opted for nonsurgical treatment with space opening for prosthetic replacement of the first maxillary molars.

Influence of natural bovine enamel roughness on bond strength after etching.

OBJECTIVE: To determine and compare the longitudinal and transverse roughness parameters of the enamel surface of bovine teeth and evaluate the influence of these parameters on bond strength. MATERIALS AND METHODS: Ninety bovine incisors were used. The surface roughness of enamel was measured with a profilometer. For each tooth, five readings were taken in the longitudinal plane and five were taken in the transverse plane of the long axis of the tooth in an area equal to the size of the bracket base. The metal brackets were bonded with Transbond XT, and bond strength was evaluated in a universal test machine. RESULTS: There was a statistical correlation (P < .01) between the longitudinal and transverse roughness measurements. There was no correlation between roughness measurements (longitudinal and transverse) and bond strength (P > .05), nor was there a correlation between total roughness (longitudinal Ra and transverse Ra) and bond strength. The Student's t-test showed that there was a statistically significant difference (P < .05) between longitudinal and transverse roughness. CONCLUSION: The transverse roughness is greater than the longitudinal roughness, there is a strong correlation between longitudinal and transverse roughness, and there is no correlation between enamel roughness and bond strength.

Root formation of an autotransplanted tooth.

Traumatic injuries with loss of anterior teeth occur more frequently in children. Treatment of the dental trauma is complex and requires a comprehensive and accurate diagnostic and treatment plan. It is also important to consider the biological, functional, esthetic, and economic aspects. The purpose of this article is to show a case report with a successful root formation and periodontal healing after autotransplantation of maxillary second right premolar in place of maxillary right central incisor site. Tooth autotransplantation may be considered as a viable treatment option instead of a conventional prosthetic and implant rehabilitation.

Clinical challenges in treating a patient with deviated dental midlines and delayed root development of the mandibular left second premolar.

This case report describes the treatment of a girl, aged 13.3 years, with a concave face and a Class I relationship on the right and Class III on the left at the first molars. The left canines were in full Class II occlusion. The overbite was excessive at 80%. The maxillary dental midline was deviated 2.0 mm to the right, and the mandibular dental midline was 3.0 mm on the opposite side with a 5-mm deviation between both arches. There was a -2-mm mandibular arch length discrepancy, but, considering the intrabony left second premolar with root-delayed development, the arch length discrepancy was -8 mm. The incisors were also retroclined. A nonextraction treatment plan was used. When space to the left of the intrabony second premolar was opened, the tooth erupted passively, and the root had a normal length. The esthetic results were functional and pleasing.

Metal and ceramic bracket effects on human buccal mucosa epithelial cells.

OBJECTIVE: To test the null hypothesis that metal and ceramic brackets have no effect on the epithelial cells of the buccal mucosa. MATERIALS AND METHODS: Two metal and two ceramic brackets were bonded in 21 individuals of both sexes. With the use of liquid-based exfoliative cytology, morphometric and morphologic changes in buccal mucosa cells adjacent to these brackets were determined and were compared at three time points: baseline (T0), 60 days after placement (T1), and 30 days after removal of the brackets (T2). RESULTS: A decrease in nuclear area and an increase in cytoplasmic area occurred in the buccal mucosa cells adjacent to the brackets at T1 (P < .01). At T2, this altered morphometry persisted only in cells adjacent to the metal brackets, although to a lesser degree than at T1 (P < .01). A greater decrease in nuclear area was noted in cells adjacent to the metal brackets than in those next to the ceramic brackets (P < .01). At T0, the proportions of surface and subsurface cells were similar, but at T1, a predominance of surface cells was observed (P < .05). At all time points, smears of cells appeared normal or normal with some inflammatory changes. CONCLUSION: The hypothesis is rejected. Placement of metal and ceramic brackets in the buccal cavity induces cellular alterations. These alterations do not suggest malignancy.

Insertional torque and axial pull-out strength of mini-implants in mandibles of dogs.

INTRODUCTION: The objectives of this study were to evaluate insertional torque of mini-implants (MI) for orthodontic anchorage, to compare their axial pull-out strength at 0 (T0), 15 (T15), and 60 (T60) days after placement, to determine initial and peri-implant cortical bone thickness, and to analyze the correlations among these variables. METHODS: Sixty MI were placed in the mandibles of 10 dogs. Peak insertional torque values were recorded, and, after the animals were killed, specimens were prepared. The MI were aligned with a testing machine to register axial pull-out strength. Cortical bone thickness was measured after removal of the MI. Statistical analyses were conducted with ANOVA and Tukey HSD tests. RESULTS: Pull-out strength and peri-implant cortical bone thickness had differences (P <0.01) at the various times. The T0 value showed the highest pull-out strength, and the smallest peri-implant cortical bone thickness was at T60. There was a regular correlation between pull-out strength and peri-implant cortical bone thickness at T0 (r = 0.44, P = 0.05). There was no correlation between insertional torque and pull-out strength, and insertional torque and initial cortical bone thickness. CONCLUSIONS: Pull-out strength is greater immediately after placement of MI, cortical bone thickness decreases because of bone resorption, and insertional torque is not an efficient method for predicting the retention of MI.

The dilemma of the open gingival embrasure between maxillary central incisors.

AIM: The aim of this report is to present the etiology, diagnosis, and treatment planning strategy in the presence of an open gingival embrasure between the maxillary central incisors. BACKGROUND: The open gingival embrasure or "black triangle" is a visible triangular space in the cervical region of the maxillary incisors. It appears when the gingival papilla does not completely fill in the interdental space. The space may occur due to: (1) disease or surgery with periodontal attachment loss resulting in gingival recession; (2) severely malaligned maxillary incisors; (3) divergent roots; or (4) triangular-shaped crowns associated with or without periodontal problems and alveolar bone resorptions. REPORT: The post-treatment prevalence in adult orthodontic patients is estimated to be around 40% compromising the esthetic result. CONCLUSION: Several methods of managing patients with open gingival embrasure exist, but the interdisciplinary aspects of treatment must be emphasized to achieve the best possible result. The orthodontist can play a significant role in helping to manage these cases. CLINICAL SIGNIFICANCE: Various treatment strategies are available to treat cases of an undesirable black triangle and are dependent on the etiology of the condition.

Electromyographic activity evaluation and comparison of the orbicularis oris (lower fascicle) and mentalis muscles in predominantly nose- or mouth-breathing subjects.

INTRODUCTION: The objective of this study was to evaluate and compare the electromyographic (EMG) activity of the orbicularis oris--lower fascicle (LOO) muscle and the mentalis muscle (MT)--in predominantly nose-breathing (PNB) and mouth-breathing (PMB) subjects. METHODS: Thirty-four subjects, 22 PNB and 12 PMB, with Class II Division 1 malocclusions were evaluated in 2001 (T1) and again in 2004 (T2), 2 years 5 months later. The age ranges of the sample were 11 years to 14 years 11 months at T1, and 13 years 4 months to 16 years 6 months at T2. EMG activity was recorded with bipolar surface electrodes at rest and during 12 movements; data were processed and normalized by the EMG highest value. The Student t test and the Mann-Whitney nonparametric test were used to compare the mean values and the variables between the observation times. RESULTS: Greater EMG activity of the MT was observed in the PMB group at rest and swallowing at T1 and T2. At T2, increased EMG activity of the LOO at blowing and pronunciation of the phoneme \b\ was observed as well as a greater increment of EMG activity of this muscle at blowing, pronunciation of the phoneme \m\, and chewing in the PMB group. In addition, greater EMG activity of the MT at chewing in the PMB group was observed at T2. CONCLUSIONS: These results suggest that mouth breathing influences EMG activity of the LOO and MT muscles.

Orthodontic intrusion of maxillary incisors: a 3D finite element method study.

OBJECTIVE: In orthodontic treatment, intrusion movement of maxillary incisors is often necessary. Therefore, the objective of this investigation is to evaluate the initial distribution patterns and magnitude of compressive stress in the periodontal ligament (PDL) in a simulation of orthodontic intrusion of maxillary incisors, considering the points of force application. METHODS: Anatomic 3D models reconstructed from cone-beam computed tomography scans were used to simulate maxillary incisors intrusion loading. The points of force application selected were: centered between central incisors brackets (LOAD 1); bilaterally between the brackets of central and lateral incisors (LOAD 2); bilaterally distal to the brackets of lateral incisors (LOAD 3); bilaterally 7 mm distal to the center of brackets of lateral incisors (LOAD 4). RESULTS AND CONCLUSIONS: Stress concentrated at the PDL apex region, irrespective of the point of orthodontic force application. The four load models showed distinct contour plots and compressive stress values over the midsagittal reference line. The contour plots of central and lateral incisors were not similar in the same load model. LOAD 3 resulted in more balanced compressive stress distribution.

Tridimensional finite element analysis of teeth movement induced by different headgear forces.

BACKGROUND: This study aimed to simulate the actions of low-pull (LP), high-pull (HP), and combined pull (CP) headgears (HGs) and to analyze tooth movement tendencies through finite element analysis. METHODS: Tomographic slices of a human maxilla with complete permanent dentition were processed by reconstruction software, and the triangular surface mesh was converted into non-uniform rational B-spline (NURBS) curves. An HG facial bow was also modulated in 3D. The teeth and bone were considered to have isotropic and linear behavior, whereas the periodontal ligament was considered to have non-linear and hyperelastic behavior. Data regarding the application points, directions and magnitudes of forces were obtained from the literature and from a dolichofacial patient with class II, division 1 malocclusion, who was treated with a CP HG. RESULTS: The CP HG promoted 37.1 to 41.1 %, and the HP HG promoted 19.1 to 31.9 % of LP distalization. The HP HG presented the highest intrusion, and the LP HG presented the highest extrusion of the first molar. The LP HG contracted the distal side, and the HP and CP HGs contracted the lingual and distobuccal roots of the second molar to a lesser degree. CONCLUSIONS: The LP HG promotes the greatest distalization, followed by the CP and HP HGs; the LP HG causes greater extrusion of the first molar, and the HP HG causes greater intrusion of the first molar. The LP HG causes greater contraction of the second molar than the HP HG.

Nicotine effect on bone remodeling during orthodontic tooth movement: histological study in rats.

INTRODUCTION: Nicotine is harmful to angiogenesis, osteogenesis and synthesis of collagen. OBJECTIVE: The aim of this study was to investigate the effect of nicotine on bone remodeling during orthodontic movement in rats. METHODS: Eighty male Wistar rats were randomly divided into three groups: Group C (control), group CM (with orthodontic movement) and group NM (nicotine with orthodontic movement) groups. The animals comprising groups C and CM received 0.9% saline solution while group NM received nicotine solution (2 mg/kg). A nickel-titanium closed-coil spring was used to induce tooth movement. The animals were euthanized and tissue specimens were histologically processed. Blood vessels, Howship's lacunae and osteoclast-like cells present in the tension and compression areas of periodontal ligaments were quantified. The extent of bone formation was evaluated under polarized light, to determine the percentage of immature/mature collagen. RESULTS: It was observed lower blood vessel densities in the NM group in comparison to the CM group, three (p < 0.001) and seven (p < 0.05) days after force application. Osteoclast-like cells and Howship's lacunae in the NM group presented lower levels of expression, in comparison to the CM group, with significant differences on day 7 (p < 0.05 for both variables) and day 14 (p < 0.05 for osteoclast-like cells and p < 0.01 for Howship's lacunae). The percentage of immature collagen was increased in the NM group in comparison to the CM group, with a statistically significant difference on day 3 (p < 0.05), day 7 (p < 0.001), day 14 (p < 0.001) and day 21 (p < 0.001). CONCLUSIONS: Nicotine affects bone remodeling during orthodontic movement, reducing angiogenesis, osteoclast-like cells and Howship's lacunae, thereby delaying the collagen maturation process in new bone matrix.

Mechanical properties of orthodontic wires on ceramic brackets associated with low friction ligatures / Propriedades mecânicas de fios ortodônticos em bráquetes cerâmicos associados com ligaduras de baixa fricção

Introduction: Few studies investigated the mechanical properties of orthodontic wires on ceramic brackets associated the ligatures. Objective: This study aimed to compare the load-deflection of orthodontic wires with round section of 0.016" made of stainless steel (SS), nickel-titanium (NiTi) and glass fiber-reinforced polymer composite (GFRPC). Material and method: Sixty specimens obtained from 10 sectioned pre-contoured arches (TP Orthodontics), were divided into 3 groups of 20 according to each type of material (1 esthetic-type wire and 2 not esthetic) and length of 50 mm. The methodology consisted of a 3-point bending test using esthetic ceramic brackets (INVU, TP Orthodontics, Edgewise, 0.022"x 0.025") as points of support. The tensile tests were performed on a mechanical test machine, at a speed of 10 mm/min, deflection of 1 mm, 2 mm and 3 mm. Friedman's Non Parametric Multiple comparisons test was used (P<0.05). Result: The nickel-titanium wire presented smaller load/ deflection compared with stainless steel. GFRPC wires had lower strength values among all groups evaluated (P<.05). The steel wire showed permanent deformation after 3 mm deflection, NiTi wire demonstrated memory effect and the esthetic type had fractures with loss of strength. Conclusion: It can be concluded that steel wires have high strength values, requiring the incorporation of loops and folds to reduce the load / deflection. NiTi and GFRPC wires produced low levels of force, however the esthetic wire was shown to fracture and break.

Introdução: Poucos estudos investigaram as propriedades mecânicas dos fios ortodônticos em bráquetes cerâmicos associados às ligaduras. Objetivo: O objetivo deste estudo foi comparar a carga-deflexão de fios ortodônticos com seção redonda de 0,016" de aço inoxidável (AI), níquel-titânio (NiTi) e composto de polímero reforçado com fibra de vidro (CPRFV). Material e método: Sessenta espécimes obtidos a partir de 10 arcos pré-contornos seccionados (TP Orthodontics), foram divididos em 3 grupos de 20 de acordo com cada tipo de material (1 fio estético e 2 não estético) e comprimento de 50 mm. A metodologia consistiu de um teste de flexão de 3 pontos usando bráquetes estéticos cerâmicos (INVU, TP Orthodontics, Edgewise, 0,022 "x 0,025") como pontos de suporte. Os ensaios de tração foram realizados em uma máquina de ensaios mecânicos, a uma velocidade de 10 mm / min, deflexão de 1 mm, 2 mm e 3 mm. Utilizou-se o teste não-paramétrico de comparações múltiplas de Friedman (P <0,05). Resultado: O fio de níquel-titânio apresentou menor carga / deflexão em relação ao aço inoxidável. Os fios CPRFV tiveram valores de resistência mais baixos entre todos os grupos avaliados (P <0,05). O fio de aço mostrou deformação permanente após deflexão de 3 mm, fio NiTi demonstrou efeito de memória e o tipo estético teve fraturas com perda de força. Conclusão: Pode-se concluir que os fios de aço têm valores de resistência elevados, exigindo a incorporação de alças e dobras para reduzir a carga / deflexão. Os fios NiTi e CPRFV produziram baixos níveis de força, porém o fio estético mostrou-se fraturado e quebrado.

Mechanical evaluation of space closure loops in orthodontics.

This study evaluated the mechanical performance of teardrop-shaped loops and teardrop-shaped loops with helix used in orthodontic space closure. Sixty retraction loops made with 0.019" x 0.025" stainless steel (SS) and beta-titanium (BT) wires were used. They were attached to a testing machine to measure the magnitudes of the sagittal force and the load-deflection ratio necessary for 1 mm, 2 mm and 3 mm activation. The results demonstrated that the BT alloy presented significantly smaller mean values (p < 0.01) of sagittal force and load-deflection than the SS alloy. The loop with the highest mean value of sagittal force and load-deflection was the teardrop-shaped loop (p < 0.01). Differences were observed in the mean values of sagittal force and load-deflection among activations, and the highest mean value was found in the activation of 3 mm, while the smallest mean value was evident in the activation of 1 mm (p < 0.01). It could be concluded that the metallic alloy used and the presence of a helix in configuration of the loops may have a strong influence on the sagittal force produced and on the load-deflection ratio; the teardrop-shaped loops and teardrop-shaped loops with helix in BT presented the release of lighter forces; the teardrop-shaped loop in SS generated a high load-deflection ratio, providing high magnitudes of horizontal force during its deactivation.

Orthodontic intrusion of maxillary incisors: a 3D finite element method study

Objective: In orthodontic treatment, intrusion movement of maxillary incisors is often necessary. Therefore, the objective of this investigation is to evaluate the initial distribution patterns and magnitude of compressive stress in the periodontal ligament (PDL) in a simulation of orthodontic intrusion of maxillary incisors, considering the points of force application. Methods: Anatomic 3D models reconstructed from cone-beam computed tomography scans were used to simulate maxillary incisors intrusion loading. The points of force application selected were: centered between central incisors brackets (LOAD 1); bilaterally between the brackets of central and lateral incisors (LOAD 2); bilaterally distal to the brackets of lateral incisors (LOAD 3); bilaterally 7 mm distal to the center of brackets of lateral incisors (LOAD 4). Results and Conclusions: Stress concentrated at the PDL apex region, irrespective of the point of orthodontic force application. The four load models showed distinct contour plots and compressive stress values over the midsagittal reference line. The contour plots of central and lateral incisors were not similar in the same load model. LOAD 3 resulted in more balanced compressive stress distribution.

Objetivo: frequentemente, no tratamento ortodôntico, é necessário o movimento de intrusão dos incisivos superiores. Assim, o objetivo deste estudo é avaliar o padrão de distribuição inicial e magnitude das tensões compressivas no ligamento periodontal (LPD) na simulação da intrusão ortodôntica dos incisivos superiores, considerando os pontos de aplicação da força. Métodos: modelos anatômicos 3D reconstruídos a partir de tomografias computadorizadas de feixe cônico foram utilizados para simular os carregamentos da intrusão dos incisivos superiores. Os pontos eleitos para a aplicação das forças foram: centralizado entre os braquetes dos incisivos centrais (LOAD 1); bilateralmente, entre os braquetes dos incisivos centrais e laterais (LOAD 2); bilateralmente, distal aos braquetes dos incisivos laterais (LOAD 3); bilateralmente, 7mm distal ao centro dos braquetes dos incisivos laterais (LOAD 4). Resultados e Conclusões: as tensões concentraram-se na região apical do LPD, independentemente do ponto de aplicação da força ortodôntica; os quatro modelos de carregamento mostraram distribuição e valores de tensão compressiva distintos na linha mediana sagital de referência; os gráficos de distribuição das tensões não foram similares para os incisivos central e lateral no mesmo modelo de carregamento; o LOAD 3 resultou em uma distribuição mais equilibrada das tensões compressivas.

Effect of etching and light-curing time on the shear bond strength of a resin-modified glass ionomer cement.

The aim of this study was to assess the influence of etching and light-curing time on the shear bond strength (SBS) and adhesive remnant index (ARI) of a resin-modified glass ionomer cement (RMGIC) upon debonding of orthodontic brackets. Sixty-eight bovine permanent incisors were obtained and embedded in acrylic resin. Edgewise metallic brackets were bonded to the teeth with Fuji Ortho LC RMGIC. The specimens were randomly assigned to 4 groups, using the following etching and light-curing times: G1: 10% polyacrylic acid and 40 s (control); G2: 37% phosphoric acid and 40 s; G3: 10% polyacrylic acid and 50 s; and G4: 37% phosphoric acid and 50 s. Shear test was performed at 0.5 mm/min and the ARI was assessed. G2 (3.6 ± 0.98 MPa) presented significantly higher (p<0.05) SBS than G1 (2.76 ± 0.86 MPa) and G4 (2.86 ± 0.68 MPa), and there was no statistically significant difference (p>0.05) between G2 and G3 (2.94 ± 0.67 MPa). ARI presented prevalence of scores 2 and 3 in all groups. RMGIC SBS enhanced with 37% phosphoric acid etching and 40 s light-curing time, but this did not occur when the light-curing time was increased, regardless of the acid used. RMGIC presented prevalence of failures at the adhesive/bracket interface.