Evaluation of caries risk reduction following preventive programs in orthodontic patients, using Cariogram computer model: A quasi-experimental trial.

OBJECTIVE: This study evaluated the effectiveness of preventive strategies on caries risk reduction in patients undergoing orthodontic treatment, using the Cariogram program. METHODS: In this quasi-experimental study, samples were selected using a convenience quota sampling technique, in a public dental school. At first, caries risk profile was determined for each subject using the Cariogram before brackets bonding. The sample size consisted of 36 patients. The intervention group (n = 18) received preventive programs, and the control group (n = 18) was trained based on the routine oral health education by means of pamphlets. Then, Cariogram parameters were calculated for patients in both groups after six months. RESULTS: The age range of participants was from 12 to 29 years. The mean percentage of the "Actual chance of avoiding new cavities" section in the intervention group increased from 45.72 ± 21.64 to 62.50 ± 17.64. However, the mean percentage of other parameters - such as "Diet", "Bacteria" and "Susceptibility" - decreased after six months (p< 0.001). Besides, the differences in the mean percentage between intervention and control group at the end of the study period (T1) related to the Cariogram parameters were statistically significant (p< 0.001). Accordingly, the mean percentage of 'Actual chance of avoiding new cavities'' parameter in the intervention group (62.50) was statistically higher than in the control group (42.44) (p< 0.001). CONCLUSION: Implementing different preventive approaches is able to reduce the caries risk in patients undergoing fixed orthodontic treatment, which can be clearly demonstrated using Cariogram program.

Evaluation of caries risk reduction following preventive programs in orthodontic patients, using Cariogram computer model: A quasi-experimental trial

ABSTRACT Objective: This study evaluated the effectiveness of preventive strategies on caries risk reduction in patients undergoing orthodontic treatment, using the Cariogram program. Methods: In this quasi-experimental study, samples were selected using a convenience quota sampling technique, in a public dental school. At first, caries risk profile was determined for each subject using the Cariogram before brackets bonding. The sample size consisted of 36 patients. The intervention group (n = 18) received preventive programs, and the control group (n = 18) was trained based on the routine oral health education by means of pamphlets. Then, Cariogram parameters were calculated for patients in both groups after six months. Results: The age range of participants was from 12 to 29 years. The mean percentage of the "Actual chance of avoiding new cavities" section in the intervention group increased from 45.72 ± 21.64 to 62.50 ± 17.64. However, the mean percentage of other parameters - such as "Diet", "Bacteria" and "Susceptibility" - decreased after six months (p< 0.001). Besides, the differences in the mean percentage between intervention and control group at the end of the study period (T1) related to the Cariogram parameters were statistically significant (p< 0.001). Accordingly, the mean percentage of 'Actual chance of avoiding new cavities'' parameter in the intervention group (62.50) was statistically higher than in the control group (42.44) (p< 0.001). Conclusion: Implementing different preventive approaches is able to reduce the caries risk in patients undergoing fixed orthodontic treatment, which can be clearly demonstrated using Cariogram program.

RESUMO Objetivo: O presente estudo usou o software Cariogram para avaliar a eficácia de estratégias preventivas para redução do risco de cáries em pacientes sob tratamento ortodôntico. Métodos: Nesse estudo quase-experimental, as amostras foram selecionadas por meio de uma técnica de amostragem por cota de conveniência, em uma faculdade pública de Odontologia. Inicialmente, o perfil de risco de cárie foi determinado para cada indivíduo usando o Cariogram antes da colagem dos braquetes. A amostra consistiu de 36 pacientes: o grupo experimental (n = 18) recebeu programas preventivos, e o grupo controle (n = 18) recebeu orientações sobre a saúde bucal por meio de folhetos. Após seis meses, os parâmetros obtidos por meio do Cariogram foram calculados novamente para os pacientes de ambos os grupos. Resultados: A faixa etária dos participantes foi de 12 a 29 anos. A porcentagem média da seção "Probabilidade real de prevenir novas cáries" no grupo experimental aumentou de 45,72 ± 21,64 para 62,50 ± 17,64. Por outro lado, a porcentagem média de outros parâmetros - como "Dieta", "Bactérias" e "Suscetibilidade" - diminuiu após seis meses (p< 0,001). Além disso, as diferenças nas porcentagens médias entre o grupo experimental e o grupo controle ao fim do estudo (T1), relacionadas aos parâmetros do Cariogram, foram estatisticamente significativas (p< 0,001). Assim, a porcentagem média do parâmetro "Probabilidade real de prevenir novas cáries" no grupo experimental (62,50) foi estatisticamente maior do que no grupo controle (42,44) (p< 0,001). Conclusão: A implementação de diferentes abordagens preventivas pode reduzir o risco de cárie em pacientes sob tratamento ortodôntico com aparelhos fixos, o que pode ser observado claramente por meio do software Cariogram.

Effect of screw access hole design on the fracture resistance of implant-supported zirconia-based restorations.

OBJECTIVE: To evaluate the effect of screw access hole design on the fracture resistance of cement-retained implant-supported zirconia-based restorations with screw access holes. MATERIALS AND METHODS: Thirty cement-retained implant-supported zirconia-based molar crown specimens were fabricated. The specimens were divided into 3 groups of 10: without access holes (C), with screw access holes (S), and with screw access holes accompanied with a surrounding zirconia wall (W). The veneering ceramic thickness was 0.8 mm in all groups. Implants were vertically mounted in a metal block. Abutments were screwed on the implants and the specimens were cemented to the abutments. A universal testing machine applied compressive forces to the specimens until fracture. Fracture resistance values of the specimens were measured. One-way analysis of variance (ANOVA) and Tukey HSD tests were used to analyze data (P < .05). RESULTS: The mean fracture resistance values were 5794.85 N for C, 2691.48 N for S, and 3878.06 N for W. The screw access hole design significantly affected the fracture resistance (P < .0001). Significant differences were found between C and S (P < .001), C and W (P < .001), and S and W (P = .026). CONCLUSIONS: The screw access hole decreased the fracture resistance. A surrounding zirconia wall for the screw access hole increased the fracture resistance. CLINICAL SIGNIFICANCE: Screw access hole design may affect the fracture resistance of cement-retained implant-supported zirconia-based restorations with screw access holes. This study introduced a screw access hole design to improve the fracture resistance of these restorations.

The Accuracy of Four Impression-making Techniques in Angulated Implants Based on Vertical Gap.

STATEMENT OF THE PROBLEM: Precision of the impression taken from implant positions significantly determines accurate fit of implant-supported prostheses. An imprecise impression may produce prosthesis misfit. PURPOSE: This study aimed to evaluate the accuracy of four impression-making techniques for angulated implants by stereomicroscope through measuring the vertical marginal gaps between the cemented metal framework and the implant analog. MATERIALS AND METHOD: A definitive cast with two 15° mesially angulated implants served as the standard reference for making all the impressions and later for accuracy evaluation. Four groups of five samples were evaluated: (1) closed-tray snap-fit transfer, (2) open-tray nonsplinted impression coping, (3) metal splinted impression coping, and (4) fabricated acrylic resin transfer cap. A gold-palladium framework was fabricated over the angulated implant abutments, the fit of which was used as reference. The gaps between the metal framework and the implant analogs were measured in sample groups. Corresponding means for each technique and the definitive cast were compared by using ANOVA and post hoc tests. RESULTS: The mean marginal gap was 38.16±0µm in definitive cast, 89±19.74µm in group 1, 78.66±20.63µm in group 2, 54.16±24.29µm in group 3, and 55.83±18.30µm in group 4. ANOVA revealed significant differences between the definitive cast and groups 1 and 2, but not with groups 3 and 4 (p< 0.05). CONCLUSION: Vertical gap measurements showed that metal splinted impression coping and fabricated acrylic resin transfer cap techniques produced quite more accurate impressions than closed-tray snap-fit transfer and open-tray nonsplinted impression coping techniques do. The fabricated acrylic resin transfer cap technique seems to be a reliable impression-making method.

The effect of inter-implant distance on retention and resistance to dislodging forces for mandibular implant-tissue-supported overdentures.

OBJECTIVES: The effect of inter-implant distance on retention and resistance of implant-tissue-supported overdentures is lacking in the literature. An in vitro study was performed to evaluate this effect for mandibular implant-tissue-supported overdentures retained by two ball attachments. MATERIALS AND METHODS: An acrylic cast of an edentulous mandible was fabricated. Three pairs of implants were symmetrically placed at both sides of the midline. The inter-implant distance was 10, 25, and 35 millimeters in positions A, B and C, respectively. A framework simulating the overdenture was fabricated on the cast. Six attachment housings were placed within the overdenture. For each sample, two ball abutments were screwed onto the implant pairs and two pink nylon inserts were seated in their respective attachment housings. The samples were tested in three groups of 15 (A, B, and C). The testing machine applied tensile dislodging forces and peak loads were measured in three directions: vertical, oblique, and anterior-posterior. A one-way ANOVA followed by Tukey's HSD was used to determine groups that were significantly different. Tests were carried out at 0.05 level of significance. RESULTS: Peak loads for the anterior-posteriorly directed dislodging forces were significantly the highest for group C (P<0.05); 21.25 N±3.05 N, while there were no statistically significant differences among groups with vertically and obliquely directed forces (P>0.05). CONCLUSION: Inter-implant distance did not affect the vertical retention and oblique resistance of mandibular implant-tissue-supported overdentures; however, it affected anterior-posterior resistance.

Covering the screw-access holes of implant restorations in the esthetic zone: a clinical report.

Screw-retained implant restorations have an advantage of predictable retention as well as retrievability, and obviate the risk of excessive sub-gingival cement commonly associated with cement retained implant restorations. Screw-retained restorations generally have screw access holes, which can compromise esthetics and weaken the porcelain around the holes. The purpose of this study is to describe the use of a separate overcasting crown design to cover the screw access hole of implant screw-retained prosthesis for improved esthetics.

The effect of repeated torque in small diameter implants with machined and premachined abutments.

BACKGROUND: Detorquing value is an important factor in the amount of preload stresses during abutment screw fastening. This study evaluated the percentage of detorque values in two-piece machined titanium and premachined cast abutments in small diameter implants. MATERIALS AND METHODS: Three groups of five samples were evaluated. Group 1 (G1), machined titanium abutments, group 2 (G2), premachined cast straight abutments that cast with gold-palladium, and group 3 (G3), premachined angled cast abutments that cast with the same alloy, were angled before casting. Each abutment was torque to 24 Ncm according to the manufacturer's instructions and detorqued five times. The means of detorquing and torquing values in all groups were recorded. The mean of detorque in each group as a percentage of the toque value was calculated. The data for all groups were compared and calculated using analysis of variance (ANOVA) and t-test. RESULTS: Mean detorque values in G1, G2, and G3 were 88.1 ± 1.69, 93.1 ± 2.68, and 80.9 ± 4.95%, respectively. The ANOVA showed significant differences in mean of applied detorque (p < .001) and torque (p = .06) tightening among different groups. G2 had significantly greater detorque values (p < .05). No significant differences were found between G1 and G2. Surprisingly, abutment screw fracture occurred in three samples of G3. CONCLUSIONS: G3 showed significant percentage torque reduction (p < .05) and exhibited abutment screw fracture during evaluation. G2 presented the lowest torque reduction. Screw fracture occurred only in G3.