Influence of bisphosphonates on alveolar bone density: a histomorphometric analysis

This study is a histomorphometrical analysis of the influence of the bisphosphonate alendronate on alveolar bone density. Eighteen male Wistar rats were randomly assigned to a control group (n = 9) that received no medication and an experimental group (n = 9) that received oral alendronate (1 mg/kg) from birth until euthanization at 3 months of age. Semi-serial 4-µm-thick transverse sections were obtained from the region between the roots of the left maxillary first molar, stained with hematoxylin and eosin, and examined with a Zeiss Axioskop II optical microscope for histomorphometric analysis. The images were captured with a digital camera coupled with the microscope and connected to a computer, and were analyzed using Image J 1.34s image-analysis software. A 1,200-point grid was positioned onto each digitized image. The number of intersection points of grid lines in the bone tissue was counted. The ratio between the number of points in the bone tissue and the total number of points of the grid (1,200) was used to determine the bone density of the analyzed tissue. Data from the control and experimental groups were compared and analyzed statistically by the Student's t-test (p = 0.05). There was no statistically significant difference (p = 0.3754) in the alveolar bone density between the control and alendronate-treated animals. It may be concluded that the bisphosphonate alendronate did not alter the morphology of the alveolar bone, maintaining its structural tissue characteristics in healthy animals.São Paulo State Research Foundation (FAPESP) and a research postgraduate scholarship granted by the Brazilian Government Research Funding Agency CAPES. The authors are indebted to the Department of Physiology of Ribeirão Preto Dental School, University of São Paulo, Brazil, and to the histotechnician MS. Fátima Aparecida Silveira from the Service Pathology of Bauru Dental School, University of São Paulo (USP), Brazi

Analysis of the dentin-pulp complex in teeth submitted to orthodontic movement in rats

In order to microscopically analyze the pulpal effects of orthodontic movement, 49 maxillary first molars of rats were submitted to orthodontic appliance composed of a closed coil spring anchored to the maxillary incisors, placed for the achievement of mesial movement. MATERIAL AND METHODS: Ten animals were used as the control group and were not submitted to orthodontic force; the other animals were divided into groups according to the study period of tooth movement, namely 1, 2, 3, 4, 5, 6 and 7 days. The investigation of pulp and periodontal changes included hyalinization, fibrosis, reactive dentin and vascular congestion. Statistical evaluation was performed between control and experimental groups and between periods of observation using non-parametric chi-square, Kruskal-Wallis and Dunn tests. RESULTS: There was no statistically significant difference concerning pulpal changes between control and experimental groups nor between periods of observation. The control group, at 3 and 5 days, revealed greater hyalinization of the periodontal ligament (

Analysis of the dentin-pulp complex in teeth submitted to orthodontic movement in rats

In order to microscopically analyze the pulpal effects of orthodontic movement, 49 maxillary first molars of rats were submitted to orthodontic appliance composed of a closed coil spring anchored to the maxillary incisors, placed for the achievement of mesial movement. MATERIAL AND METHODS: Ten animals were used as the control group and were not submitted to orthodontic force; the other animals were divided into groups according to the study period of tooth movement, namely 1, 2, 3, 4, 5, 6 and 7 days. The investigation of pulp and periodontal changes included hyalinization, fibrosis, reactive dentin and vascular congestion. Statistical evaluation was performed between control and experimental groups and between periods of observation using non-parametric chi-square, Kruskal-Wallis and Dunn tests. RESULTS: There was no statistically significant difference concerning pulpal changes between control and experimental groups nor between periods of observation. The control group, at 3 and 5 days, revealed greater hyalinization of the periodontal ligament (p<0.05), whereas root resorption was significantly greater at 5 and 7 days (p<0.05). CONCLUSION: No morphological change from the effect of induced tooth movement could be found in the dentin-pulp complex. In addition, no inflammatory or pulp degeneration, detectable in optical microscopy, was found in experimental groups

Analysis of predictors of root resorption in the orthodontic treatment (Part II)

This study aims to analyze the predictors of root resorption in orthodontic treatment. From 407 records, 377 pretreatment and posttreatment periapical radiographs of permanent maxillary central incisors of 199 patients treated with fixed appliances were divided according to the apical morphologies: pipetteshaped, dilacerated, pointed, rounded and rectangular; crown/root ratio; and presence or absence of partial hypodontia. Changes in root length between the onset and completion of orthodontic treatment were measured in digitized images and statistically compared using T student, one-way ANOVA and Tukey tests. The apical morphology influenced the occurrence of root resorption; teeth with rounded and rectangular apical morphologies were more resistant to root resorption (.001 and .0007, respectively). Short teeth and the presence of partial hypodontia or multiple partial hypodontia did not present greater tendency to root resorption (.1008 and .1544, respectively). The results indicated that abnormal apical morphology is a predictor of external apical root resorption after corrective orthodontic therapy. However, short teeth and partial hypodontia did not increase the prevalence of apical resorption. The susceptibility or individual predisposition to tooth resorptions during orthodontic treatment may be related to the apical morphology

Experimental tooth movement in murines: study period and direction of microscopic sections

AIM: This study aims to elucidate the relevant microscopic aspects of induced tooth movement in murines with regard to: (1) different study periods; and (2) transverse and longitudinal directions of microscopic sections. Experimental studies on induced tooth movement in murines use variable study periods and directions of microscopic sections, including those studies that specifically use the model adopted by Heller and Nanda in 1979. This manuscript was prepared in order to contribute to: (1) selection of the best study design for future studies on induced tooth movement in murines, and (2) improve the analysis criteria to be used by other investigators. METHODS: The study was conducted on 50 male Wistar rats with 90 days of age, submitted to induced tooth movement for periods of 3, 5, 7 and 9 days. The maxillary left first molar was submitted to mesial inclination by application of 75cN of force. Qualitative microscopic analysis evaluated the tissue and cellular phenomena secondary to induced tooth movement, at the different study periods and on transverse and longitudinal sections. RESULTS: Among the phenomena investigated, hyaline areas of periodontal ligament were mostly observed at 5 days, and root resorptions were remarkable and well delineated at 9 days. Both phenomena affected mainly the distal roots, especially the distobuccal root. CONCLUSION: Considering the present objective, study periods of 5 to 9 days and transverse microscopic sections may be suggested for future studies on this subject.OBJETIVO: este trabalho tem por finalidade explicitar aspectos microscópicos relevantes da movimentação dentária induzida em murinos quanto aos: (1) diferentes períodos de observação e (2) planos dos cortes microscópicos transversais e longitudinais. Os estudos experimentais sobre a movimentação dentária induzida em murinos variam quanto aos períodos e planos de cortes microscópicos, mesmo os trabalhos que utilizam especificamente o modelo de Heller e Nanda, de 1979. Para contribuir (1) na escolha do melhor design experimental de movimentação dentária induzida em murinos em futuros trabalhos, e (2) no aperfeiçoamento dos critérios de análise por outros pesquisadores, propusemo-nos a publicar este artigo. MÉTODOS: Empregaram-se 50 ratos machos Wistar, com 90 dias de vida, submetidos à movimentação dentária induzida por períodos de 3, 5, 7 e 9 dias. Utilizou-se movimento de inclinação mesial no primeiro molar superior esquerdo, com uma força equivalente a 75cN. A análise microscópica qualitativa avaliou os fenômenos teciduais e celulares decorrentes da movimentação dentária induzida, nos diferentes períodos de observação e entre os cortes microscópicos transversais e longitudinais. RESULTADOS: dos fenômenos observados, as áreas hialinas tiveram expressão máxima no período de 5 dias e as reabsorções radiculares apresentaram-se exuberantes e bem demarcadas no período de 9 dias. Nos dois fenômenos, as raízes mais afetadas foram as distais, especialmente a raiz distovestibular. CONCLUSÃO: mediante o delineamento proposto, pode-se sugerir, para futuros trabalhos nesta linha de pesquisa, períodos de análise de 5 a 9 dias e cortes microscópicos transversais.Universidade Federal de São Paulo (UNIFESP) Escola Paulista de MedicinaUSP FOBUNIFESP, EPMSciEL

Root morphology can be a risk factor for periodontal damage and root resorption in orthodontic movement

e study evaluated, using histomorphometry, the percentage of hyaline area in periodontal ligament (PDL) and root resorption in orthodontic tooth movement (OTM). Methods: Ten rats were divided into two groups. G3 Group (n=5), with 3 days of OTM and G7 Group (n=5), with 7 days of OTM. A Control Group (n=5) consisted of contralateral teeth of each animal, which were not moved. Maxillary left first molar was moved, using stainless steel spring connected to the incisors with 40g force. Microscopic analysis was done in transversal sections of the mesiovestibular (MV) and distovestibular (DV) roots in the cervical level. Results: There was a PDL hyaline area in the DV root of 6.2% in G3 and 1.8% in G7. The root resorption area in G7 was 0.9%. On MV root and Control Group were not found occurrences of hyaline areas in PDL and no root resorption. Conclusions: Based on the results obtained, it might be concluded that smaller roots showed higher frequency of hyaline areas and root resorption

Predisposição genética, hereditariedade e reabsorções radiculares em Ortodontia: cuidados com interpretações precipitadas: uma análise crítica do trabalho de Al-Qawasmi et al Genetics predisposition, heredity and radicular resorption, in Orthodontics: cares with precipitated interpretations and a critical analysis of Al-Qawasmi´s work

O trabalho de Al-Qawasmi et al.¹, publicado em março de 2003 pelo American Journal of Orthodontics and Dentofacial Orthopedics, procurou estabelecer uma predisposição genética para justificar as reabsorções dentárias em Ortodontia, mas apresentou algumas limitações metodológicas e equívocos na interpretação de seus resultados. A análise criteriosa deste artigo ressalta que, na maioria, estas limitações foram mencionadas e reconhecidas pelos autores na discussão do trabalho, mas o seu resumo e título foram muito taxativos e conclusivos. A linguagem de estudos genéticos nem sempre é familiar a todos os clínicos e isto também requer uma análise esclarecedora à luz de uma visão mais aplicada ao cotidiano ortodôntico. Referenciar ou citar este trabalho de Al-Qawasmi et al.¹, para afirmar de forma taxativa que se demonstrou a natureza hereditária das reabsorções dentárias em Ortodontia, pode denotar falta de conhecimento sobre o assunto ou uma leitura ou compreensão apenas do seu título. Ou ainda, a citação deste trabalho como prova definitiva de associação entre hereditariedade e reabsorções dentárias em Ortodontia pode traduzir também o desejo de excluir da prática clínica a responsabilidade de planejar de forma individualizada e detalhada cada tratamento com base no conhecimento das possibilidades e limitações técnicas oferecidas pela ciência ortodôntica, bem como nas suas bases biológicas, por exemplo, valorizando a morfologia radicular e da crista óssea alveolar e o papel dos cementoblastos na proteção da superfície radicular.<br>The study published in the American Journal of Orthodontics and Dentofacial Orthopedics last March by Al-Qawasmi et al. tried to implicate dental resorption during orthodontic treatment to genetic predisposition. The methodology used, however, presents limitations and interpretative mistakes of the results. When analyzing the article sensibly, one is able to find that these limitations, mostly acknowledged and mentioned by the authors in the discussion, does not allow concluding as they did in the end or even being so decisive in the abstract. Since most clinicians are not familiar with genetic terminology, an elucidative analysis is required in order to apply this knowledge to everyday life in orthodontic practice. When referencing or citating Al-Qawasmi et al. one must be careful its limitations acknowledged by the authors themselves, despite their decisive title. Affirming that the referred paper demonstrates the heritable nature of root resorption in Orthodontics may reveal lack of knowledge on the subject, an inappropriate interpretation of it or even the exclusive reading of its title. In another hypothesis, citating this study as decisive scientific proof of heritability implicated in dental resorption in Orthodontics may indicate the wish to exonerate the clinician of responsibility to consider root and alveolar crest morphology when individualizing treatment plan based on a deeper knowledge of Orthodontic techniques

Em busca de uma causa à parte da Ortodontia: hereditariedade e reabsorção apical em pacientes tratados ortodonticamente. Uma análise crítica do trabalho de Harris, Kineret e Tolley In search of a cause apart of Orthodontics: heredity and apical resorption in patients treated Orthodontically. A critical analysis of Harris, Kineret, Tolley’s work

Exclusivamente a partir da equivalência radiográfica do padrão e intensidade de reabsorção dentária em tratamento ortodôntico de 103 irmãos, Harris, Kineret e Tolley12 tentaram impingir um caráter hereditário a este fenômeno sem considerar a morfologia dentária e maxilar, nem tampouco outros fatores envolvidos na etiopatogenia das reabsorções. No trabalho fica claro que entre os objetivos principais dos autores estava atribuir à hereditariedade a ocorrência de reabsorções dentárias durante o tratamento ortodôntico para aliviar em parte as responsabilidades profissionais perante os pacientes e a sociedade. Mas nos parece mais lógico que o profissional devesse habilitar-se para fazer a previsibilidade das reabsorções dentárias com base em seus planejamentos, considerando a morfologia radicular, o tipo de ápice dentário, a proporção coroa-raiz e a morfologia da crista óssea alveolar, bem como evitando escolher, sempre que possível, os procedimentos que mais usualmente estão associados à reabsorção radicular. Se o paciente apresentar-se com morfologias desfavoráveis e ainda assim necessitar de procedimentos associados a um maior risco de reabsorção em seu tratamento, que o mesmo seja informado e conscientizado que as reabsorções dentárias apicais serão um custo biológico para a recuperação de sua estética e função. Considerando: 1) a grande limitação proporcionada pelo diagnóstico de reabsorções apicais em radiografias panorâmicas e telerradiografias em norma lateral (cefalométricas); 2) a ausência de análise da morfologia dentária e da crista óssea alveolar; e 3) principalmente a falta de um grupo controle para comparar se os resultados seriam equivalentes, ou não, em uma população semelhante, sem qualquer parentesco, mas com as mesmas características dentomaxilares; pode-se afirmar que as conclusões do trabalho estão severamente comprometidas em sua credibilidade científica. Tanto a abordagem empregada na discussão quanto as conclusões obtidas pelos autores, sobre correlação entre genótipo, fenótipo e reabsorção dentária, parecem despropositadas, pois não houve estudos envolvendo células, nem tampouco uma metodologia de identificação de genes ou aplicação de qualquer técnica cujos resultados permitissem inferências desta natureza.<br>Harris, Kineret, Tolley12 tried to implicate heritability to root resorption exclusively though radiographic equivalence between the pattern of resorption intensity after orthodontic treatment in 103 siblings. Neither dental nor facial morphology or any other etiopathogenic factor of root resorption was considered, whatsoever.It is clear in this study that the authors´ main goal was to attribute root resorption during orthodontic treatment to heritability in order to lighten the professional’s share of responsibility before patients and society. It seems more logic that the professional should try to predict root resorption when considering on treatment plan the root and alveolar crest morphology, the type of apex, crown-root proportion, and avoiding procedures known to cause more resorption. If a patient presents unfavorable morphology and still needs procedures associated with a higher risk of resorption, than he or she must be warned and informed that apical root resorption will be a biological cost to regain estetics and function. Considering on this paper: (1) the limitations to evaluate apical resorption in panoramic and cephalometric radiographs; (2) the absence of dental and alveolar crest morphology analysis; and (3) the lack of a control group in order to compare if the results would be equivalent in a similar population with no family ties but with same maxilofacial conditions; one can affirm that the scientific credibility of the conclusions are severely damaged. The conclusions drawn by the authors about genotype and phenotype concerning root resorption seem unfounded, since there was no cell analysis or gene identification method to permit such inferences