Periodontal ligament influence on the stress distribution in a removable partial denture supported by implant: a finite element analysis

Objective: The non-homogenous aspect of periodontal ligament (PDL) has been examined using finite element analysis (FEA) to better simulate PDL behavior. The aim of this study was to assess, by 2-D FEA, the influence of non-homogenous PDL on the stress distribution when the free-end saddle removable partial denture (RPD) is partially supported by an osseointegrated implant. Material and Methods: Six finite element (FE) models of a partially edentulous mandible were created to represent two types of PDL (non-homogenous and homogenous) and two types of RPD (conventional RPD, supported by tooth and fibromucosa; and modified RPD, supported by tooth and implant [10.00x3.75 mm]). Two additional FE models without RPD were used as control models. The non-homogenous PDL was modeled using beam elements to simulate the crest, horizontal, oblique and apical fibers. The load (50 N) was applied in each cusp simultaneously. Regarding boundary conditions the border of alveolar ridge was fixed along the x axis. The FE software (Ansys 10.0) was used to compute the stress fields, and the von Mises stress criterion (sigma vM) was applied to analyze the results. Results: The peak of sigma vM in non-homogenous PDL was higher than that for the homogenous condition. The benefits of implants were enhanced for the non-homogenous PDL condition, with drastic sigma vM reduction on the posterior half of the alveolar ridge. The implant did not reduce the stress on the support tooth for both PDL conditions. Conclusion: The PDL modeled in the non-homogeneous form increased the benefits of the osseointegrated implant in comparison with the homogeneous condition. Using the non-homogenous PDL, the presence of osseointegrated implant did not reduce the stress on the supporting tooth.

Avaliação da inclinação dentoalveolar e dimensões do arco superior em mordidas cruzadas posteriores tratadas com aparelho expansor removível e fixo

OBJETIVO: avaliar as diferenças produzidas nas dimensões e forma de arco pelos tratamentos com aparelho expansor fixo tipo Hyrax e aparelho expansor removível tipo Placa de Hawley com parafuso expansor palatino centralizado. MATERIAL E MÉTODOS: foram selecionados modelos de estudo iniciais e finais de 31 crianças portadoras de mordida cruzada posterior, de ambos os gêneros, de origem étnica diversa e na fase da dentadura mista, tratadas nos cursos de Graduação e Pós-Graduação em Ortodontia do Departamento de Clínica Infantil da Faculdade de Odontologia de Araraquara - UNESP. Destas crianças, 15 foram tratadas com uso do aparelho expansor fixo tipo Hyrax e as demais 16 crianças foram tratados com expansão rápida da maxila efetuada com o aparelho expansor fixo. Foram realizadas medidas das distâncias intercaninos e intermolares, da inclinação do processo alveolar e inclinação dentária nas imagens escaneadas do arco superior e do contorno do palato, obtido com auxílio de um template ajustável e do programa de análises Radiocef Studio. RESULTADOS E CONCLUSÕES: os resultados indicam uma mudança significante nas distâncias intercaninos e intermolares em ambos os grupos e uma inclinação dentária e do processo alveolar para vestibular significante no grupo tratado com o aparelho expansor fixo. A expansão conseguida pelo aparelho expansor fixo foi aproximadamente o dobro da promovida pelo aparelho expansor removível.

Moebius Syndrome: Clinical Manifestations in a Pediatric Patient

Moebius syndrome is a congenital, nonprogressive disorder clinically characterized by loss of facial expression, impaired stomatognathic system functions, incapacity to close the eyelids, and several oral impairments. The purpose of this paper was to present the clinical manifestations and the dental treatment in a 5-year, 2-month-old male Moebius syndrome patient. The child presented with facial asymmetry, difficulty performing facial mimic movements and pronouncing some letters, and compromised suction, mastication, breathing, and deglutition. An intraoral examination revealed hypofunction of the perioral muscles, cheeks and tongue, ankyloglossia, anterior open bite, and absence of carious lesions and dental anomalies. The dental treatment consisted of frenectomy and further placement of a removable orthodontic appliance with a palatal crib for correction of the anterior open bite. After 12 months of follow-up, anterior open bite decreased and speech, deglutition, and mastication improved. (Pediatr Dent 2009;31:289-93) Received March 8, 2008 vertical bar Lost Revision July 22, 2008 vertical bar Revision Accepted July 28, 2008

Accidental swallowing of orthodontic expansion appliance key

Ingestion of a foreign object, including a dental object, can lead to a trip to the emergency room. This article describes the accidental swallowing of a key that was used to activate a rapid maxillary expander. An orthodontic patient swallowed the key while trying to activate the appliance at home. The object's trajectory was followed on radiographs until it was eliminated. Possible clinical complications, legal implications of this situation, and practices for prevention are described. (Am J Orthod Dentofacial Orthop 2011;140:266-8)

Maxillary complete denture movement during chewing in mandibular removable partial denture wearers

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Effect of oral hygiene education and motivation on removable partial denture wearers: longitudinal study

The purpose of this study was to determine the effect of two different preventive oral hygiene education and motivation programmes on the plaque and gingival index, as well as denture hygiene of patients provided with removable partial denture (RPD) during a 12-month follow-up.A total of 53 partially edentulous patients were recruited for this study. The presence or absence of plaque and gingival bleeding by gentle probing was scored on all tooth surfaces at the preliminary visit. The plaque and gingival indexes were measured using the Loe index. Following treatment, the patients were randomly divided into three groups. In Control Group I, subjects were instructed to continue their personal oral hygiene routine. In Group II, participants were given verbal instructions and a self-educational manual on oral hygiene without illustrations. In Group III, oral hygiene guidance was delivered using a combination of verbal instructions and a self-teaching manual. To evaluate the effect of the different modes of instruction, the presence or absence of plaque and gingival bleeding was scored on all tooth surfaces (day zero examination) and re-examined 7, 15 and 30 days, 3, 6 and 12 months following RPD placement. The state of denture hygiene was evaluated 7, 15 and 30 days and 3, 6 and 12 months following rehabilitation. Parametric statistics was applied to dental plaque and gingival indexes. For accumulation of plaque and calculus on the RPD, non-parametric statistic was applied.The frequency of plaque found during the preliminary visit was higher than that found in the other periods. With regard to gingival index, significant difference was found between the preliminary visit examination and other periods. There was a significant difference in the plaque accumulation on the denture surface between groups I and III.The different methods of oral hygiene instruction used in this study indicate that the type of education was not of significant importance.

Presença de leveduras do gênero candida na saliva de pacientes com diferentes fatores predisponentes e de indivíduos controle

Os microrganismos do gênero Candida são, em geral, comensais da cavidade bucal, mas, em determinados indivíduos e em situações específicas, podem transformar-se na forma parasitária, produzindo candidoses bucais. O objetivo deste trabalho foi analisar a presença das espécies do gênero Candida na saliva de indivíduos controle, comparando com pacientes que apresentavam diferentes fatores predisponentes. Foram avaliados 493 pacientes, divididos em 7 grupos: prótese total, prótese parcial removível, periodontite crônica de adulto, respiração bucal, aparelho ortodôntico fixo, aparelho ortodôntico removível e aparelho extrabucal. O grupo controle consistiu de 570 indivíduos que não apresentavam nenhum desses fatores, divididos em 2 grupos: infantil e adulto. Foram realizados o isolamento e a identificação das espécies do gênero Candida. Os resultados mostraram maior porcentagem de pacientes positivos para Candida nos grupos com fatores predisponentes em relação aos controles. Houve predominância de isolamento de C. albicans em todos os grupos, porém, os pacientes com fatores predisponentes apresentaram diversidade maior de espécies

Correlation between factors associated with the removable partial dentures use and Candida spp. in saliva

Objectives: To correlate the presence and number of Candida spp. in the saliva of wearers of removable partial dentures retained with precision attachments with the proportion of metal/acrylic resin present in the dentures. Methods: Saliva samples from 40 removable partial denture wearers (test) and one paired sample of individuals, non- wearers of any type of removable denture (control) were collected, seeded, and the colony forming units of Candida counted and identified. The metal/acrylic resin proportion of each denture was quantified, using silicone plates pressed over each denture. Results: Candida spp. was found in the saliva of 80% of the individuals in the test group and 65% of the control, with C. albicans being themost prevalent species. The test group presented with the highest number of colony forming units of Candida per ml of saliva, and there wasweak correlation between this number and the metal and resin area of the denture (Pearson's coefficient of correlation). Greater prevalence and a higher number of colony forming units of Candida per ml of saliva occurred in removable partial denture wearers ( p = 0.04) with a weak positive correlation between the metal and resin area and the number of colony forming units of Candida per ml of saliva. However, this correlation was more significant for the area of resin. Correlation between factors associated with the removable partial dentures use and Candida spp. in saliva

Influence of the banded Herbst appliance on dental changes in mixed dentition

OBJECTIVE: This prospective clinical study was conducted with the purpose of evaluating the influence of the banded Herbst appliance on dental changes during the early treatment of Class II malocclusion. METHOD: The sample consisted of 15 prepubertal subjects (12 boys and 3 girls, initial age: 9 years and 6 months) who were treated with the Herbst appliance. Treatment effects were compared with those of a Class II Division 1 group of 15 subjects (8 boys and 7 girls, mean initial age 9 years and 1 month), not treated orthodontically. Statistical analysis was performed using Student t-test with 5% significance level. RESULTS: The results showed that treatment with the banded Herbst appliance in the mixed dentition stage tended to upright maxillary incisors (mean: 4.14°). The maxillary molars were distalized and intruded significantly (mean 2.65 mm and 1.24 mm, respectively), the lower incisors slightly protruded anteriorly (mean 1.64 mm) and the molars showed no significant changes in the horizontal and vertical directions. Furthermore, significant improvements were noted in overbite (1.26 mm), overjet (4.8 mm) and molar relationship (12.08 mm). CONCLUSIONS: Changes in the upper dental arch were found to be greater than changes in the lower arch. Furthermore, mandibular anchorage loss was reduced due to the anchorage system used in the study.

Cephalometric evaluation of skeletal alterations induced by Herbst appliance during mixed dentition

OBJECTIVE: The present prospective clinical study was designed in order to evaluate horizontal and vertical skeletal alterations induced by the use of Herbst appliance in individuals with Class II, division 1 malocclusion during mixed dentition stage. METHODS: The sampling consisted of 15 pre-pubertal individuals (12 boys and 3 girls; initial age 9 years and 6 months), who were treated with Herbst appliance for a period of 7 months. The effects of the treatment were compared to a group of 15 individuals with Class II, division 1 malocclusion (8 boys and 7 girls, initial age averaged 9 years and 1 month), orthodontically untreated, who were followed up for a period of 12 months. Statistical analysis was performed with Student's t-test with significance level at 5%. RESULTS: It was showed that the treatment with Herbst appliance in mixed dentition stage has restricted maxilla growth. Mandibular and palatal planes have not undergone significant alteration; however, anterior and posterior facial heights have increased significantly. Facial convexity and maxillomandibular relationship were altered positively. Mandible has positioned significantly forward and its effective length increased 2.5 times more than the increase observed in control group. CONCLUSION: It was possible to conclude that Herbst appliance was able to provide satisfactory results in individuals during mixed dentition stage.

Treatment effects produced by the Bionator appliance. Comparison with an untreated Class II sample

The purpose of this retrospective investigation was to evaluate the dentoalveolar and skeletal cephalometric changes of the Bionator appliance on individuals with a Class II division 1 malocclusion. Lateral cephalograms of 44 patients were divided into two equal groups. The control group comprised 22 untreated Class II children (11 males, 11 females), with an initial mean age of 8 years 7 months who were followed without treatment for a period of 13 months. The Bionator group (111 males, 11 females) had an initial mean age of 10 years 8 months, and were treated for a mean period of 16 months. Lateral cephalometric headfilms were obtained of each patient and control at the beginning and end of treatment.The results showed that there were no changes in forward growth of the maxilla in the experimental group compared with the control group. However, the Bionator treatment produced a statistically significant increase in mandibular protrusion, and in total mandibular and body lengths. There were no statistically significant differences in craniofacial growth direction between the Bionator group and the control group, although the treated patients demonstrated a greater increase in posterior face height. The Bionator appliance produced labial tipping of the lower incisors and lingual inclination of the upper incisors, as well as a significant increase (P < 0.01) in mandibular posterior dentoalveolar height. The major effects of the Bionator appliance were dentoalveolar, with a smaller significant skeletal effect. The results indicate that the correction of a Class II division 1 malocclusion with the Bionator appliance is achieved not only by a combination of mandibular skeletal effects, but also by significant dentoalveolar changes.