Angle Class II, Division 2 Malocclusion and Association with Late Eruption

Objective: To verify the dental age of individuals with Angle Class II, division 2 malocclusion. Material and Methods: The sample consisted of 200 panoramic radiographs of schoolchildren from the city of Fortaleza in the state of Ceará, in the northeast of Brazil. These radiographs were divided into two groups (N=100): a Control group comprising radiographs of patients with normal occlusion and a CIID2 group comprising radiographs of patients with an Angle Class II, division 2 malocclusion. The Demirjian method was used to identify dental age. All the radiographs were evaluated by a sole duly trained and calibrated technician. The Kappa coefficient for inter-annotator agreement was 0.98 based on the criteria of eruption stage of each tooth. Statistical analysis was performed using the Chi-squared test, Student's t-test and the Mann-Whitney test, with a level of significance of 5%. Results: There was a significant statistical difference between the dental ages of the groups tested. The CIID2 group had a lower dental age than the control group, signifying late eruption in patients with an Angle Class II, division 2 malocclusion. Conclusion: Patients with an Angle Class II, division 2 malocclusion had a lower dental age than patients with normal occlusion, suggesting that orthodontic treatment should be delayed. The first molars, second pre-molars and canines suffered late eruption.

Passivity of Conventional and CAD/CAM Fabricated Implant Frameworks

The objective of this research was to evaluate the passivity by measuring the passive fit and strain development of frameworks screwed on abutments, made by CAD/CAM technology, and to compare these parts with samples manufactured by conventional casting. Using CAD/CAM technology, four samples were made from zirconia (Zircad) and four samples were manufactured from cobalt-chrome (CoCrcad). The control groups were four specimens of cobalt-chrome, made by one-piece casting (CoCrci), with a total of 12 frameworks. To evaluate the passive fit, the vertical misfit at the abutment-framework interface was measured with scanning electron microscopy (250×) when only one screw was tightened. The mean strain in these frameworks was analyzed by photoelasticity test. A significant difference in the passive fit was observed between the control and sample groups. CoCrcad exhibited the best value of passive fit (48.76±13.45 µm) and CoCrci the worst (187.55±103.63 µm); Zircad presented an intermediate value (103.81±43.15 µm). When compared to the other groups, CoCrci showed the highest average stress around the implants (17.19±7.22 kPa). It was concluded that CAD/CAM-fabricated frameworks exhibited better passivity compared with conventionally fabricated frameworks. CAD/CAM-fabricated Co-Cr frameworks may exhibit better passive fit compared with CAD/CAM-fabricated zirconia frameworks. Even so, similar levels of stress were achieved for CAD/CAM-fabricated frameworks.

O objetivo desta pesquisa foi avaliar a passividade através da medição da tensão induzida e adaptação passiva em infra-estruturas parafusadas sobre pilares, confeccionadas por tecnologia CAD/CAM, e comparar estas amostras com peças fabricadas por fundição convencional. Usando a tecnologia de CAD/CAM, quatro amostras foram feitas em zircônia (ZirCAD) e quatro amostras foram fabricados em cobalto-cromo (CoCrcad). Os grupos controle foram quatro espécimes de cobalto-cromo, feitos por fundição em monobloco (CoCrci), totalizando 12 infra-estruturas. Para avaliar a adaptação passiva, a diferença vertical entre a infraestrutura e o pilar protético foi medido em microscopia eletrônica de varredura (250 ×) quando apenas um parafuso foi apertado. A tensão média nestas infraestruturas foi analisada através do teste de fotoelasticidade. Foi observada uma diferença significativa na passividade entre os grupos controle e demais amostras. CoCrcad exibiu melhor valor de adaptação passiva (48,76±13,45 mm) e CoCrci o pior (187,55±103,63 mm), Zircad apresentou um valor intermediário (103,81±43,15 µm). Quando comparado com os outros grupos, CoCrci apresentou a maior tensão média ao redor dos implantes (17,19±7,22 kPa). Concluiu-se que a tecnologia CAD/CAM exibiu maior passividade em comparação com as infraestruturas confeccionadas pela técnica convencional. Infraestruturas confeccionadas em Co-Cr através do CAD/CAM apresentaram maior adaptação passiva em comparação com as amostras confeccionadas por CAD/CAM em zircônia. Entretanto, níveis de estresse similares foram obtidos para as estruturas fabricadas por CAD/CAM.

Bacterial microleakage at the implant-abutment interface in Morse taper implants

AIM: To evaluate the microleakage at the implant-abutment (I-A) interface of Morse tapered implants inoculated with different volumes of bacterial suspension. METHODS: Morse tapered I-A sets were selected and divided in two groups depending on the type of abutment: passing screw (PS) and solid (S), and then subdivided into four subgroups (n=6) according to the suspension volume: PS1: 0.1 µL; PS3: 0.3 µL; PS5: 0.5 µL; PS7: 0.7 µL; S1: 0.1 µL; S3: 0.>3 µL; S5: 0.5 µL and S7: 0.7 µL. A control test was performed to verify the presence of external contamination during the inoculation and the implants were incubated for microbiological analysis. The microleakage was evaluated every 24 h for 7 days by the clarity of solution. After this period, the implants were disassembled for confirmation of bacterial viability. RESULTS: All the specimens with 0.7 µL and one sample of S5 presented turbidity in the control test indicating external contamination, and were excluded from the study. After 7 days of observation, none of the specimens presented positive results for microleakage and the bacterial viability was confirmed in all specimens. The 0.1 µL and 0.3 µL volumes did not present bacterial microleakage, meaning that these volumes may be inadequate for analysis. CONCLUSIONS: None of the sets evaluated showed bacterial microleakage at the I-A interface and the volume of 0.7 µL exceeded the internal capacity of the implants...

Stress analysis of different configurations of 3 implants to support a fixed prosthesis in an edentulous jaw

This study's aims was to evaluate the stress distribution in a mandibular implant-supported prosthesis and peri-implant bone considering implant quantity, diameter and position using linear 3-D finite element analysis. Models of an anterior jaw comprised 4 groups according to implant quantity, diameter, and position: control group C, 5 regular implants; R, 3 regular implants; W, 3 wide implants; and DTR, 3 regular implants with the distal ones tilted 30º distally. The cantilever was loaded with an axial load of 50 N. Data was evaluated using von Mises stress on implants and maximum principal stress and microstrain on the bone. The W group showed the lowest value of maximum principal stress in peri-implant bone of the loaded side (4.64 MPa) when compared to C (5.27 MPa), DTR (5.94 MPa), and R (11.12 MPa). Lower stress values in the loaded implants were observed in the experimental groups when compared to the C group. However, the unloaded implants presented opposite results. All the screws of the W group presented lower stress values when compared to the C group. However, the R and DTR groups presented an increase in stress values with the exception of the loaded screw. A reduction in the number of implants associated with wider implants reduced the stress in the bone and prosthetic components.

Comparison of methods to evaluate implant-abutment interface

Aim: To compare two main methods of two-dimensional measurement of fit at the implant prosthodontic interface, testing the hypothesis that optical microscopy (OM) can reliably and efficiently scanning electronic microscopy (SEM). Methods: Four frameworks with four titanium abutments joined with titanium bars were used. The implant-abutment interfaces were examined by three different methods, forming 3 groups: analysis by OM (40x), and analysis by SEM at 300x and 500x. Readings were taken at the mesial and distal proximal surfaces on the horizontal and vertical axes of each implant (n=32). One-way ANOVA with a significance level of 5% was used for statistical analysis. Results: Neither the horizontal fit nor vertical fit values of the 3 groups presented statistically significant differences (p=0.410 and p=0.543). Conclusions: OM was found to be an accurate two-dimensional method for abutment-framework or implant-abutment interface measurements, with lower costs than SEM. SEM micrographs at 500x presented technical difficulties for the readings that might produce different results.

Micro-leakage at the implant-abutment interface with different tightening torques in vitro

OBJECTIVES: This study evaluated the microleakage at the implant/abutment interface of external hexagon (eH) implants and abutments with different amounts of bacteria and tightening torques. MATERIAL AND METHODS: A bacterial suspension was prepared to inoculate the implants. The first phase of this study used nine EH implants and abutments that were divided into three groups with different amounts of bacterial suspension (n=3): V0.5: 0.5 µL; V1.0: 1.0 µL e V1.5: 1.5 µL, and tightened to the manufacturer's recommended torque. The second phase of this experiment used 27 assemblies that were similar to those used in the first phase. These samples were inoculated with 0.5 µL of bacterial suspension and divided into three groups (n=9). T10: 10 Ncm; T20: 20 Ncm and T32: 32 Ncm. The samples were evaluated according to the turbidity of the broth every 24 hours for 14 days, and the bacteria viability was tested after that period. The statistical evaluation was conducted by Kruskal-Wallis testing (p<.05). RESULTS: During the first phase, groups V1.0 and V1.5 was presented with bacterial contamination in all samples after 24 h. During the second phase, two samples from group T10 and one from T20 presented positive results for bacterial contamination. Different amounts of bacterial solution led to overflow and contamination during the first 24 h of the experiment. The tightening torques did not statistically affect the microleakage in the assemblies. However, the group that was tightened to 32 Ncm torque did not show any bacterial contamination. CONCLUSION: After 14 days of experimentation, the bacteria were proven to remain viable inside the implant internal cavity.

Prótese destacável com sistema “Swivel Loc” – relato de caso clínico / Detachable prosthesis with Swivel Loc system – a clinical case report

A reabilitação total maxilar com próteses implantossuportadas representa em algumas situações clínicas dificuldades quanto a estética, fonética, suporte labial e higienização. As próteses destacáveis implantossuportadas são uma opção de tratamento frente a essa situação, onde o uso de encaixes permite a conexão entre uma prótese removível e uma infraestrutura metálica, sendo estéticos e funcionalmente eficientes. O objetivo deste trabalho foi de apresentar por meio de um caso clínico a confecção de uma protese destacável do sistema “Swivel Loc” como alternativa de aperfeiçoar a previsibilidade dessas reabilitações

The total rehabilitation of maxilla with supported implant prostheses represent in some clinical difficulties regarding aesthetics, phonetics, lip support and hygiene. The detachable implant supported dentures are a treatment option when faced with this situation, the use of attachments allows a connection between a removable prosthesis and a metallic infrastructure, being aesthetic and functionally efficient. The aim of this work was present through a clinical case the making of a detachable prosthesis with Swivel Loc system as an alternative to improve the predictability of these rehabilitations

Evaluation of screw loosening on new abutment screws and after successive tightening

This study evaluated the loss of the torque applied after use of new screws and after successive tightening. Four infrastructures (IE), using UCLA castable abutment type, were cast in cobalt-chromium alloy and new abutment screws (G1) were used in a first moment. Subsequently, the same abutment screws were used a second time (G2) and more than two times (G3). The values of the torques applied and detorques were measured with a digital torque wrench to obtain the values of initial tightening loss ( percent). Data were analyzed by ANOVA and Tukey's test (?=0.05). Significant differences were observed between the G1 (50.71 percent ± 11.36) and G2 (24.01 percent ± 3.33) (p=0.000) and between G1 (50.71 percent ± 11.36) and G3 (25.60 percent ± 4.64) (p=0.000). There was no significant difference between G2 and G3 (p=0.774). Within the limitations of the study, it may be concluded that the percentage of the initial torque loss is lower when screws that already suffered the application of an initial torque were used, remaining stable after application of successive torques.

O objetivo deste estudo foi avaliar a perda do torque inicial, quando usados novos parafusos de pilares e após sucessivos apertos. Quatro infra-estruturas (IE), utilizando pilares calcináveis tipo UCLA, foram fundidas em liga de cobalto-cromo, onde novos parafusos de pilares foram utilizados (G1) em um primeiro momento. Posteriormente os mesmos parafusos de pilares foram utilizados em um segundo momento (G2), e depois por mais duas vezes (G3). Os valores de torque e detorque aplicados foram mensurados a partir de um torquímetro digital para obtenção dos valores de perda do torque inicial ( por cento). Os dados foram coletados e submetidos à análise de variância e teste de Tukey (p<0,05). Foram observadas diferenças estatisticamente significantes entre os grupos G1 (50,71 por cento ± 11,36) and G2 (24,01 por cento ± 3,33) (p=0,000) and the groups G1 (50,71 por cento ± 11,36) and G3 (25,60 por cento ± 4,64) (p=0,000). Os maiores valores foram encontrados para o grupo G1. Não houve diferença estaticamente significante entre os grupos G2 e G3 (p=0,774). Dentro das limitações deste estudo, pôde-se observar que a porcentagem de perda de torque inicial foi menor quando os parafusos já haviam sofrido a aplicação do primeiro torque, se mantendo estáveis após os demais torques.

Rapid denture fabrication for institutionalized patients / Confecção rápida de prótese total para pacientes institucionalizados

PURPOSE: Edentulism is a common condition among the elderly population. However, it is difficult for elderly subjects who are institutionalized, hospitalized, or bedridden to visit dental offices for the repair or replacement of broken dentures. This paper describes a fast technique with minimum clinical sessions to fabricate a new maxillary denture. CASE DESCRIPTION: An institutionalized 78-year-old man with an extremely damage broken maxillary denture complained about repairing his denture. With the impossibility of repairing, the technique described was proposed so as to offer a treatment that would maximize the comfort of the patient. The maxilla-mandibular relationship was done at the first clinical session, after fabricating the maxillary resin baseplate in mouth, by fixing the old complete mandibular denture with the maxillary wax plane. At the second clinical session, the esthetics and function of artificial teeth was checked and final impression was made to the denture installation at next session. CONCLUSION: The reduced number of clinical sessions is a convenient option for clinicians to provide a more comfortable treatment for institutionalized or bedridden patients. This technique is also particularly useful when a replacement denture is urgently required, allowing its installation within few hours.

OBJETIVO: O edentulismo é uma condição comum dentre a população idosa. Entretanto, quando estes indivíduos encontram-se institucionalizados, hospitalizados ou acamados, consultar um cirurgião-dentista para reparo ou substituição de próteses totais pode ser uma situação difícil. Neste caso, é relatada uma técnica mais rápida para confecção de uma prótese total superior em um número mínimo de sessões clínicas. DESCRIÇÃO DO CASO: Indivíduo institucionalizado de 78 anos de idade, apresentando uma prótese extremamente danificada após deixá-la cair sobre o chão, queixava de necessidade de reparo na mesma. Na impossibilidade de reparo, foi proposta esta técnica descrita para oferecer um tratamento com maior conforto para o paciente. O relacionamento maxilo-mandibular foi feito na primeira sessão clínica, após confeccionar a base de prova diretamente em boca, fixando a própria prótese inferior do paciente com o plano de cera. Na segunda sessão clínica, a prova estética e funcional é feita e a moldagem final realizada para instalação da prótese na sessão seguinte. CONCLUSÃO: O número reduzido de sessões clínicas é uma opção conveniente para os clínicos e gera um tratamento mais confortável para indivíduos institucionalizados ou acamados. Esta técnica também pode ser útil para substituição de prótese total em caráter de urgência, onde a prótese pode ser instalada no mesmo dia ou no dia seguinte.