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Objective: To evaluate the null hypothesis that there is no difference in a set of clinical predictors of potentially impacted canines between low-risk patients with and without displaced canines. Methods: The normal canine position group consisted of 30 patients with 60 normally erupting canines ranked in sector I (age, 9.30 ± 0.94 years). The displaced canine group comprised 30 patients with 41 potentially impacted canines ranked in sectors II to IV (age, 9.46 ± 0.78 years). Maxillary lateral incisor crown angulation, inclination, rotation, width, height, and shape, as well as palatal depth, arch length, width, and perimeter composed a set of clinical predictors, which were evaluated on digital dental casts. Statistical analyses consisted of group comparisons and variable correlations (p < 0.05). Results: There was a significant association between sex and mesially displaced canines. Unilateral canine displacement was more prevalent than bilateral displacement. The crown of the maxillary lateral incisors was significantly angulated more mesially and rotated mesiolabially in low-risk patients with displaced canines, who also had a shallower palate and shorter anterior dental arch length. Lateral incisor crown angulation and rotation, as well as palatal depth and arch length, were significantly correlated with the canine displacement severity. Conclusions: The null hypothesis was rejected. Maxillary lateral incisor angulation inconsistent with the "ugly duckling" stage as well as a shallow palate and short arch length are clinical predictors that can significantly contribute to the early screening of ectopic canines in low-risk patients.
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INTRODUCTION: This research aimed to investigate the dentofacial characteristics of patients with Incontinentia Pigmenti (IP) (or Bloch-Sulzberger) syndrome in childhood, juvenile, and adulthood developmental stages. METHODS: Fifteen female patients with a clinical diagnosis of IP, genetically confirmed by molecular testing, were included in this study. The records of 25 nonsyndromic females with Class I occlusion and lateral cephalograms obtained at similar developmental stages were selected from the American Association of Orthodontists Foundation Legacy Collection as a control group. Dentofacial features of subjects with IP and those in the control group were compared statistically using t test and Mann-Whitney rank-sum test (significance was defined as P <0.05). RESULTS: In general, patients with IP had shorter maxillary and mandibular length, straight skeletal profile, hypodivergent growth pattern with a tendency to mandibular protrusion, shorter anterior facial height, Class III compensatory positioning of incisors, more retruded lips, and smaller maxillary incisor exposure. The degree of hypodontia severity had a significant impact on skeletal, dental, and soft-tissue features in patients with IP. CONCLUSIONS: The results of this study showed that, since childhood, the dentofacial characteristics of patients with IP were progressively distancing from those of nonsyndromic patients with Class I occlusion, presenting their own orthodontic needs.
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Incontinência Pigmentar , Adulto , Cefalometria , Estudos Transversais , Feminino , Humanos , Incisivo , MaxilaRESUMO
BACKGROUND: The mechanical strength of mini-implants is a critical factor due to their small diameters. Currently, it is not possible to state whether there is a relevant difference between the mechanical properties of stainless steel (SS-MIs) and titanium alloy mini-implants (TA-MIs). The objective of this study was to test the null hypothesis that there is no difference in the mechanical strength of SS-MIs and TA-MIs, and to analyze, by scanning electron microscopy (SEM), the SS-MI, and TA-MI threads resistance to morphological damage after insertion. METHODS: A standardized sample of 504 SS-MIs and TA-MIs with diameters ranging from 1.2 mm to 1.8 mm was used. Torsional fracture was performed in 154 MIs. Flexural strength of 280 MIs was evaluated at 1 mm and 2 mm-deflection. The threads of 70 MIs were morphologically analyzed by scanning electron microscopy (SEM), before and after their insertion in high-density artificial bone blocks. Comparisons between SS-MIs and TA-MIs were performed with t tests or Mann-Whitney U tests. A multiple linear regression analysis was used to evaluate the influence of variables on the ranging of MI mechanical strength. RESULTS: SS-MIs had higher fracture torque. The mean difference between the SS-MIs and TA-MIs fracture torque was of 4.09 Ncm. The MI diameter explained 90.3% of the total variation in fracture torque, while only 2.2% was explained by the metallic alloy. The SS-MI group presented a higher deformation force during the 1mm and 2mm-deflection. The mean difference between the flexural strength of SS and TA-MIs at 1 mm and 2 mm-deflection was of 18.21 N and 17.55 N, respectively. There was no noticeable morphological damage to the threads of SS-MIs and TA-MIs. CONCLUSIONS: The null hypothesis was rejected. SS-MIs were 13.2% and 20.2% more resistant to torsional fracture and deflection, respectively. The threads of the SS-MIs and TA-MIs were not damaged during the insertion and removal process. Thus, the use of SS-MI can reduce the fracture risk without increasing the MI diameter.
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Procedimentos de Ancoragem Ortodôntica , Aço Inoxidável , Ligas , Humanos , Laboratórios , Teste de Materiais , Desenho de Aparelho Ortodôntico , Estresse Mecânico , Titânio , TorqueRESUMO
OBJECTIVE: To compare the efficacy of vacuum-formed and banded space maintainers for deciduous second molar space maintenance during the mixed dentition. SETTING AND SAMPLE POPULATION: The study sample comprised thirty children in the mixed dentition (age range, 5.9 to 9.8 years) with early loss of at least one deciduous second molar. METHODS: This was a parallel-group, randomized, active-controlled clinical trial. Patients were randomly allocated to space maintenance performed with vacuum-formed or banded space maintainers with a 1:1 allocation ratio. The main outcome was any change in mesiodistal width of the extraction space. Secondary outcomes included the lingual rolling or axial rotation of the permanent first molar adjacent to the extraction site and extrusion of the antagonist tooth. Dental casts were obtained before appliance installation (T0), after 3 months (T1) and after 6 months (T2). Digital dental casts were measured using Dolphin 3D software. Chi-square, t test or Mann-Whitney and ANOVA or Friedman test were used for intra- and intergroup comparisons (P < .05). RESULTS: Baseline characteristics were similar between groups except for chronological age. Statistically, but not clinically significant space loss (mean, 0.32 mm; SD, ± 0.39) occurred with the vacuum-formed space maintainer only at the first trimester (T0-T1). Lingual rolling and axial rotation of the first permanent molar were not significant, as well as extrusion of the antagonist tooth. CONCLUSIONS: The results of this study suggested that both tested devices were effective in maintaining space after early extraction of the deciduous second molar over a period of 6 months.
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Dentição Mista , Mantenedor de Espaço em Ortodontia , Humanos , Dente Molar , Dente Decíduo , VácuoRESUMO
INTRODUCTION: Due to potential impact of the effects of ionizing radiation used in medical and dental examinations on public health in recent years, many studies are being conducted to quantify the radiation dose values, evaluate scanners, and indicate factors that could influence or reduce radiation doses. OBJECTIVES: This study aimed to evaluate, by a systematic review, the factors that influence the effective radiation dose associated with cone beam computed tomography and respective effects, and compared the effective dose of different cone beam computed tomography (CBCT) scanners with similar exposure parameters. MATERIALS AND METHODS: A search was conducted on five databases from 2007 to 2015. RESULTS: The search identified 741 abstracts, among which 44 eligible articles were retrieved in full text. Twenty-three studies met the inclusion criteria and were included. Additional copper filter was evaluated in one study, patient size in 2 studies, region of interest in 1 study, use of a thyroid shield in 2 studies, scan angle in 3 studies, exposure time in 10 studies, FOV diameter in 17 studies, FOV height in 17 studies, kV in 16 studies, mA in 18 studies, mAs in 13 studies, voxel in 8 studies, and resolution in 3 studies. When similar exposure parameters were evaluated, it was observed that CBCT scanner with lower effective dose was Kodak® 9000C 3D (mean 21.2 µSv) in selected studies. CONCLUSIONS: Thirteen factors were related to changes in the effective dose emitted by different scanners. More studies are needed to identify the image quality requirements in addition to measure the radiation. CLINICAL RELEVANCE: Studies that give more information for professionals who request and interpret the exams and for technicians who perform 3D images about effective radiation dose associated with CBCT are necessary.
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Tomografia Computadorizada de Feixe Cônico , Doses de Radiação , Humanos , Imageamento TridimensionalRESUMO
INTRODUCTION: The purpose of this study was to evaluate the short-term impact of rapid maxillary expansion (RME) on the eruption paths of ectopically and normally erupting maxillary canines in the mixed dentition. METHODS: Thirty-two patients with 49 ectopically erupting canines (EEC group; age, 9.53 ± 1.10 years) and 18 patients with 27 normally erupting canines (NEC group; age, 9.25 ± 1.06 years) underwent RME. Thirty-six subjects with 54 normally erupting canines composed the untreated control group (UC group; age, 9.03 ± 0.72 years). Horizontal, vertical, and angular positions of canines and adjacent teeth were evaluated in the expanded (EEC and NEC groups) and unexpanded (UC group) patients using panoramic radiographs taken at 2 times with a 1-year interval. The radiographic evaluation methods included score ranking and proportional measurements to minimize panoramic radiograph limitations. Statistical comparisons were performed among the groups (P <0.05). RESULTS: Before expansion, the EEC group's canines were significantly closer to the midline, more distant from the occlusal plane, and more mesially angulated than those in the UC group. After expansion, the canine positions in the EEC and UC groups were similar, whereas the NEC group had a more favorable canine position for eruption. The EEC and NEC groups showed similar canine positional changes, whereas the UC group had the smallest changes. The positions of teeth adjacent to the canine were also significantly affected by RME, and these changes may be associated with improvement of the ectopic canine position. CONCLUSIONS: The changes produced by RME reduced the percentage of ectopic eruption paths and maintained the nonectopic eruption percentage.
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Dente Canino/anatomia & histologia , Dente Canino/patologia , Técnica de Expansão Palatina/efeitos adversos , Reabsorção da Raiz/etiologia , Erupção Ectópica de Dente/etiologia , Erupção Dentária , Brasil , Criança , Dente Canino/efeitos dos fármacos , Arco Dental/diagnóstico por imagem , Dentição Mista , Feminino , Humanos , Incisivo/anatomia & histologia , Incisivo/diagnóstico por imagem , Masculino , Maxila/diagnóstico por imagem , Maxila/patologia , Radiografia Panorâmica , Reabsorção da Raiz/diagnóstico por imagem , Ápice Dentário/anatomia & histologia , Ápice Dentário/patologia , Erupção Ectópica de Dente/diagnóstico por imagem , Técnicas de Movimentação Dentária/efeitos adversos , Raiz Dentária/anatomia & histologia , Raiz Dentária/diagnóstico por imagem , Dente DecíduoRESUMO
Several uprighting mechanics and devices have been used for repositioning tipped molars. "Kissing molars" (KMs) are an uncommon tooth impaction involving 2 severely tipped mandibular molars with their occlusal surfaces positioned crown to crown, with the roots pointing in opposite directions. Orthodontic uprighting of KMs has not been a usual treatment protocol, and it can be a challenging task due to the severe tipping and double impaction, requiring efficient and well-controlled uprighting mechanics. An innovative skeletally anchored cantilever, which uses the torque principle for uprighting tipped molars, is suggested. This torqued cantilever is easy to manufacture, install, and activate; it is a well-known torque that is effective for producing root movement. A successful treatment of symptomatic KMs, involving the first and second molars, was achieved with this cantilever. Thus, clinicians should consider the suggested uprighting mechanics and orthodontic device as a more conservative alternative to extraction of KMs, depending on the patient's age, involved teeth in KMs, tipping severity, and impaction positions.
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Dente Molar/patologia , Procedimentos de Ancoragem Ortodôntica/métodos , Desenho de Aparelho Ortodôntico/métodos , Técnicas de Movimentação Dentária/métodos , Dente Impactado/terapia , Torque , Brasil , Cefalometria , Criança , Implantes Dentários , Análise do Estresse Dentário , Feminino , Humanos , Má Oclusão Classe II de Angle/terapia , Mandíbula/diagnóstico por imagem , Dente Molar/diagnóstico por imagem , Níquel/química , Procedimentos de Ancoragem Ortodôntica/instrumentação , Desenho de Aparelho Ortodôntico/instrumentação , Aparelhos Ortodônticos , Braquetes Ortodônticos , Fios Ortodônticos , Planejamento de Assistência ao Paciente , Radiografia Panorâmica , Estresse Mecânico , Titânio/química , Coroa do Dente , Erupção Dentária , Técnicas de Movimentação Dentária/instrumentação , Raiz Dentária/anatomia & histologia , Raiz Dentária/patologia , Dente Impactado/complicações , Dente Impactado/diagnóstico por imagem , Resultado do TratamentoRESUMO
Objetivo: Comparar a autopercepção da criança e do adolescente em relação à má oclusão e sua motivação ao tratamento ortodôntico. Material e métodos: A amostra de 216 jovens foi dividida em dois grupos: Grupo 1 (136 crianças com idade entre 8 e 10,9 anos) e Grupo 2 (80 adolescentes de 11 a 14 anos de idade). A autopercepção e o nível de necessidade de tratamento foram avaliados por meio do Componente Estético (AC) e do Componente de Saúde Dentária (DHC) do Índice de Necessidade de Tratamento Ortodôntico (IOTN). A motivação para o tratamento ortodôntico foi avaliada por meio de questionários. Os dados foram analisados estatisticamente por meio dos testes Qui-quadrado e Mann-Whitney. Resultados: As crianças apresentaram um escore de IOTN-AC estatisticamente maior do que o dos adolescentes. A oclusão foi avaliada pelo IOTN-DHC e mostrou que a maioria dos jovens apresentou necessidade definida de tratamento ortodôntico no Grupo 1 (55%) e no Grupo 2 (43%). As principais razões citadas pelos grupos avaliados para justificar o uso do aparelho foram: "Acho bonito usar aparelho" e "Meus pais acham importante usar aparelho". Conclusão: As crianças foram mais críticas com a autoimagem que os adolescentes e a motivação para tratamento estava relacionada à estética e à opinião dos pais.(AU)
Objective: To compare child and adolescent's self-perception of malocclusion and their motivation for orthodontic treatment. Material and methods: A sample of 216 individuals was divided into two groups: Group 1 (136 children aged from 8 to 10.9 years) and Group 2 (80 adolescents aged from 11 to 14 years). Self-perception and treatment need level were evaluated using Aesthetic Component (AC) and Dental Health Component (DHC) of the Orthodontic Treatment Need Index (IOTN). Motivation for orthodontic treatment was evaluated through questionnaires. Data were statistically analyzed through Chi-square and Mann-Whitney tests. Results: Child group presented an IOTN-AC score statistically higher than the adolescents. Occlusion was assessed by IOTN-DHC and showed that the majority of the children presented definitive orthodontic treatment need in Group 1 (55%) and Group 2 (43%). The main reasons mentioned by both groups to justify the orthodontic appliance use were: "I think it is beautiful to wear orthodontic appliance" and "My parents think it is important to use orthodontic appliance". Conclusion: Children were more critical about their self-perception than adolescents, and the motivation for orthodontic treatment was related to aesthetics and parents' opinions.(AU)
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Humanos , Criança , Adolescente , Índice de Necessidade de Tratamento Ortodôntico , Má Oclusão , AutoimagemRESUMO
Objetivo: determinar o posicionamento vertical da crista marginal (PVCM) e do centro lingual da coroa clínica (PVCC), bem como comparar a discrepância vertical de posição entre cristas marginais (DVCM) e centros de coroas clínicas (DVCC) de dentes adjacentes. Material e métodos: uma amostra foi selecionada a partir de um grupo de 1.430 pacientes. Duzentos pacientes que preenchiam os critérios de seleção tiveram seus modelos de gesso iniciais selecionados. Após a padronização do posicionamento do modelo de gesso, o PVCM e PVCC dos dentes posteriores de ambos os arcos foram medidos, permitindo o cálculo da DVCM e DVCC. Um medidor digital de altura com precisão de 0,01 mm foi utilizado para as avaliações, e os dados foram comparados estatisticamente (p < 0,05). Resultados: em geral, os dentes posteriores adjacentes apresentaram diferentes PVCM e PVCC. As variáveis DVCM e DVCC foram significantemente diferentes, exceto entre pré-molares inferiores. As diferenças entre DVCM e DVCC foram clinicamente significantes (> 0,5 mm). O PVCC foi significantemente correlacionado com a idade do paciente. Conclusão: as diferenças entre DVCM e DVCC indicaram que o centro lingual da coroa clínica não foi uma referência anatômica confiável para predizer o nivelamento das cristas marginais. A idade do paciente parece ser um fator adicional que limita o uso adequado deste referencial.
Objective: to determine the vertical positioning of the marginal ridge (VPMR) and clinical crown center (VPCC) regarding the tip of the lingual cusp, and to compare the vertical discrepancy between adjacent marginal ridges (VDMR) and clinical crown centers of adjacent posterior teeth (VDCC). Material and methods: the sample was selected from a pool of 1.430 patients. Two hundred initial dental casts were selected from patients that met the selection criteria. After standardization of the dental cast positioning, VPMR and VPCC of posterior teeth were measured in both arches, allowing the calculation of VDMR and VDCC. Measurements were performed with a digital height gauge and accuracy of 0.01 mm. Data were statistically compared at p < 0.05. Results: in general, adjacent posterior teeth had different VPMR and VPCC. The variables VDMR and VDCC were significantly different, except between mandibular premolars. The differences between VDMR and VDCC were clinically significant (> 0.5 mm). Patient age and VPCC were significantly correlated. Conclusion: the differences between VDMR and VDCC showed that lingual center of the clinical crown was not a reliable anatomical reference to predict the marginal ridge leveling. Patient's age seems to be an additional factor limiting the adequate use of this landmark.
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Aparelhos Ortodônticos , Coroa do Dente , Braquetes Ortodônticos , Erupção DentáriaRESUMO
Este relato de caso teve como objetivo exemplificar e discutir, à luz da literatura científica, a influência da Classe II, subdivisão, tipo 1, sobre a posição dos terceiros molares inferiores, bem como avaliar o impacto das extrações assimétricas de 3 pré-molares sobre a erupção destes dentes. Previamente ao tratamento, a paciente apresentava os terceiros molares inferiores impactados, sendo que no lado da relação molar de Classe II a impacção era mais severa, provavelmente em decorrência da característica dentoalveolar determinante desta má oclusão, que é a posição mais distal do primeiro molar inferior no lado da Classe II. Após o tratamento observou-se a desimpacção do terceiro molar inferior no lado da Classe I, onde foi realizada a extração de um pré-molar. Porém, no lado oposto, onde nenhuma extração foi realizada, o terceiro molar inferior permaneceu impactado. Concluiu-se que o profissional deve atentar para a propensão da Classe II, subdivisão, tipo 1, apresentar o terceiro molar inferior no lado da Classe II em condição mais desfavorável à erupção, e que este fato, por si, não justificaria a realização de extrações simétricas de 4 pré-molares em razão da menor proporção de sucesso deste protocolo, quando aplicado à Classe II, subdivisão, tipo 1. A extração assimétrica de 2 pré-molares superiores e um pré-molar inferior no lado da Classe I pode favorecer a erupção e/ou desimpacção do terceiro molar inferior neste lado, indicando a necessidade de postergar a decisão da extração.
This case report aimed to illustrate and discuss, in the light of scientific literature, the influence of Type 1 Class II subdivision malocclusion on the positioning of the mandibular third molar and to evaluate the impact of the asymmetric extraction of 3 premolars on the eruption of that tooth. Before treatment, the patient had impacted mandibular third molars. The Class II side showed more severe impaction, probably due to the main dentoalveolar feature of this malocclusion, which is the mandibular first molar more distally positioned on the Class II side. After treatment, mandibular third molar were disimpacted on the Class I side, where premolar extraction was performed. However, in the opposite side, where no extraction was performed, the impaction of the mandibular third molar was kept unchanged. It was concluded that the professional should be aware that the Type 1 Class II subdivision malocclusion is prone to present less favorable condition for eruption of the mandibular third molar on the Class II side. Nevertheless, this fact itself could not justify making symmetric extraction of 4 premolars because this protocol presents a smaller occlusal success rate when applied to the Type 1 Class II subdivision malocclusion. In addition, asymmetric extraction of 2-maxillary premolars and a mandibular premolar on the Class I side can benefit the eruption and/or disimpaction of the mandibular third molar in this side, indicating the need to postpone the extraction decision.
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Humanos , Feminino , Adulto , Má Oclusão Classe II de Angle , Dente Serotino , Ortodontia Corretiva , Extração Dentária , Dente ImpactadoRESUMO
Objetivo: comparar as alterações produzidas pelos braquetes autoligados e convencionais durante o estágio inicial de alinhamento, realizado em arcos dentários inicialmente compatibilizados. Material e métodos: dez typodonts com uma mesma má-oclusão de classe I foram igualmente distribuídos para receber braquetes autoligados e convencionais, colados em posição padronizada. As imagens digitais dos typodonts foram obtidas nas fases pré e pós-alinhamento com arcos .012" e .014" nitinol. Uma medição computadorizada foi realizada para avaliar o índice de irregularidade de Little, as dimensões transversal e sagital dos arcos, e o grau de rotação dos dentes em cada fase do experimento. A comparação dos grupos foi realizada pelo teste U de Mann-Whitney. Resultados: após o alinhamento inicial, o grau de irregularidade dos dentes foi semelhante entre os grupos. O grupo com braquete autoligado foi propenso a apresentar arcos mais largos e menor protrusão dos incisivos superiores, mas a diferença foi pequena e de significado clínico questionável. O grupo com braquetes convencionais apresentou um melhor controle da rotação dos dentes nesta fase inicial do alinhamento. Conclusão: o tipo de braquete não influenciou no grau de mudança do índice de irregularidade de Little. As diferenças estatísticas observadas nas dimensões transversal e sagital dos arcos devem ser consideradas com cautela quanto à sua significância clínica. O controle da rotação dentária com o aparelho convencional foi um pouco melhor nesta fase específica do alinhamento.
Objective: to compare the changes produced by self-ligating and conventional brackets during initial alignment stage on dental arches initially matched. Material and methods: ten typodont sets with standardized Class I malocclusion were equally divided to receive self-ligating and conventional brackets bonded in a standardized position. Digital images of the typodonts were obtained pre- and post-alignment with .012- and .014-inch archwires. Computerized measurement was performed to evaluate the Little's irregularity index, transverse and sagittal arch dimensions and tooth rotation. Groups comparison were performed with Mann-Whitney U test. Results: teeth irregularity degree was similar between the groups after initial alignment. Self-ligating group was prone to present wider arches and smaller upper incisors proclination, but the difference was small and its clinical significance is questionable. Conventional group showed a better tooth rotational control in this specific alignment phase. Conclusion: bracket type cannot predict Little's irregularity index change. Significant statistical differences in transverse and sagittal arch dimensions should be considered with caution regarding its clinical significance. Rotational control of the conventional appliance was a bit better for this specific alignment phase.
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Arco Dental , Precisão da Medição Dimensional , Má Oclusão , Técnicas de Movimentação Dentária/métodos , Braquetes OrtodônticosRESUMO
Four premolar extractions is a successful protocol to treat Class I malocclusion, but it is a less efficient way when compared with other Class II treatment protocols. Objective: The objective of this study was to evaluate the influence of anteroposterior discrepancy on the success of four premolar extractions protocol. For that, treatment efficiency of Class I and complete Class II malocclusions, treated with four premolar extractions were compared. Methods: A sample of 107 records from 75 Class I (mean age of 13.98 years - group 1) and 32 Class II (mean age of 13.19 years - group 2) malocclusion patients treated with four premolar extractions was selected. The initial and final occlusal status of each patient was evaluated on dental casts with the PAR index. The treatment time was calculated based on the clinical charts, and the treatment efficiency was obtained by the ratio between the percentage of PAR reduction and treatment time. The PAR index and its components, the treatment time and the treatment efficiency of the groups were statistically compared with t tests and Mann-Whitney U-test. Results: The Class II malocclusion patients had a greater final PAR index than Class I malocclusion patients, and similar duration (Class I - 28.95 mo. and Class II - 28.10 mo.) and treatment efficiency. Conclusion: The treatment of the complete Class II malocclusion with four premolar extractions presented worse occlusal results than Class I malocclusion owing to incomplete molar relationship correction. .
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Humanos , Masculino , Feminino , Criança , Adolescente , Adulto , Adulto Jovem , Dente Pré-Molar/cirurgia , Má Oclusão Classe I de Angle/terapia , Má Oclusão Classe II de Angle/terapia , Extração Seriada/métodos , Fatores Etários , Análise de Regressão , Estudos Retrospectivos , Índice de Gravidade de Doença , Fatores Sexuais , Estatísticas não Paramétricas , Fatores de Tempo , Resultado do TratamentoRESUMO
Purpose. This study evaluated the influence of recycling process on the torsional strength of mini-implants. Materials and Methods. Two hundred mini-implants were divided into 4 groups with 50 screws equally distributed in five diameters (1.3 to 1.7 mm): control group (CG): unused mini-implants, G1: mini-implants inserted in pig iliac bone and removed, G2: same protocol of group 1 followed by sonication for cleaning and autoclave sterilization, and G3: same insertion protocol of group 1 followed by sonication for cleaning before and after sandblasting (Al2O3-90 µ) and autoclave sterilization. G2 and G3 mini-implants were weighed after recycling process to evaluate weight loss (W). All the screws were broken to determine the fracture torque (FT). The influence of recycling process on FT and W was evaluated by ANOVA, Mann-Whitney, and multiple linear regression analysis. Results. FT was not influenced by recycling protocols even when sandblasting was added. Sandblasting caused weight loss due to abrasive mechanical stripping of screw surface. Screw diameter was the only variable that affected FT. Conclusions. Torsional strengths of screws that underwent the recycling protocols were not changed. Thus, screw diameter choice can be a more critical step to avoid screw fracture than recycling decision.
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UNLABELLED: Four premolar extractions is a successful protocol to treat Class I malocclusion, but it is a less efficient way when compared with other Class II treatment protocols. OBJECTIVE: The objective of this study was to evaluate the influence of anteroposterior discrepancy on the success of four premolar extractions protocol. For that, treatment efficiency of Class I and complete Class II malocclusions, treated with four premolar extractions were compared. METHODS: A sample of 107 records from 75 Class I (mean age of 13.98 years--group 1) and 32 Class II (mean age of 13.19 years--group 2) malocclusion patients treated with four premolar extractions was selected. The initial and final occlusal status of each patient was evaluated on dental casts with the PAR index. The treatment time was calculated based on the clinical charts, and the treatment efficiency was obtained by the ratio between the percentage of PAR reduction and treatment time. The PAR index and its components, the treatment time and the treatment efficiency of the groups were statistically compared with t tests and Mann-Whitney U-test. RESULTS: The Class II malocclusion patients had a greater final PAR index than Class I malocclusion patients, and similar duration (Class I - 28.95 mo. and Class II - 28.10 mo.) and treatment efficiency. CONCLUSION: The treatment of the complete Class II malocclusion with four premolar extractions presented worse occlusal results than Class I malocclusion owing to incomplete molar relationship correction.