Evaluation of linear dimensional accuracy of hard chairside and laboratory heat cure reline resins at different time intervals after processing.

Context: Relining with heat cure denture base resin is time‑consuming and the patient has to remain without dentures within this period. Recently, some autopolymerizing resins marketed as hard chairside reline systems with low exothermic heat allow the dentists to reline prosthesis directly in the mouth. However, the decision to use these materials must be based on physical properties such as dimensional accuracy that directly influences the accuracy of fit of the denture base. Aim: The aim was to compare the linear dimensional changes of two hard chairside reline resins with two laboratory heat cure resins at 3 times intervals after processing. Settings and Design: A stainless steel split mold (International Organization for Standardization 1567) was used for sample fabrication. Five measurements of the reference dimensions (AB and CD) were measured directly from the mold and the samples with a profile projector, and mean difference were calculated. Subjects and Methods: Forty samples were fabricated by incorporating the split mold into first pour of denture flasks and packing each of the chairside reline resins (“Kooliner” and “Ufi Gel Hard”) and laboratory heat cure resins (“Dental Products of India Heat Cure” and “Trevalon”). The mean difference in dimensional change at 3 times intervals (0 h, 4 days and 2 months) were calculated and subjected to statistical analysis. Statistical Analysis Used: One‑way ANOVA, RMANOVA and post hoc Tukey’s tests. Results: All resins showed different levels of significant shrinkage (P < 0.001) after processing (T0) ranging from −0.128 to −0.310 mm. After 4 days (T1), there was significant shrinkage (P < 0.001) ranging from −0.168 to −0.296 mm. After 2 months (T2), there was again significant shrinkage (P < 0.001) ranging from −0.018 to −0.216 mm. Chairside reline resins showed less dimensional shrinkage at each time interval than the laboratory heat cure resins. Conclusions: Hard chairside resins are dimensionally accurate than the laboratory heat cure resins.

Repair of bilateral cleft lip and nose by the Mulliken method: a case report

The simultaneous surgical correction of bilateral cleft lip and nasal deformity has become a more common surgical technique that has greatly changed conventional strategies for secondary nasal correction. Mulliken has been known as one of the earliest proponents for the synchronous repair of bilateral cleft lip and nasal deformity, and he emphasized the responsibility of the treating surgeon to evaluate nasolabial growth by comparing anthropometric measurements with age-matched normal patients. Good outcomes from this surgical method have been reported in clinical cases worldwide. Herein, we describe the management of two cases of bilateral cleft repair, following the principles and methods established by Mulliken. We also provide a relevant review of the literature.

Dimensional Changes of Ceromer Crown by Water Absorption / 대한치과보철학회지

STATEMENT OF PROBLEM: The increasing demand for esthetic restorations has been required developing new materials for tooth colored restoration. Ceromer (Ceramic Optimized Polymer) has some advantages over porcelain, and has gained increasing popularity in restorative dentistry. However, there is little information on the dimensional changes in a clinical restoration in moist conditions. PURPOSE: This study examined the dimensional changes in Ceromer restorations with a clinical crown shape that were fabricated in a clinical manner. MATERIAL AND METHODS: The crowns for the maxillary central incisor were fabricated with two Ceromers (BelleGlass(R) and Targis(R)) using a similar clinical restoration manufacturing technique. A total of twenty specimens were prepared and immersed in distilled water at room temperature to allow for water absorption. The weight, height and width were measured at 24, 72 and 168 hours. The accumulated ratios of the changes were calculated and evaluated using a paired t-test and an independent independent t-test. RESULTS: The dimensions and weight increased with increasing soaking time. Targis(R) showed significant differences in height and weight between 24 hours and the other times (P < .05). BelleGlass(R) showed significant differences in width and weight between 24 hours and the other times. The two materials showed different changing patterns of the dimensions but there were no statistically significant differences between them. CONCLUSION: The dimensions and weight of the Ceromer restorations were changed by water absorption. The clinical crown shaped specimen showed more complicated dimensional changes than the simplified specimens.

Influence of storage period and effect of different brands of acrylic resin on the dimensional accuracy of the maxillary denture base

The aim of this study was to evaluate the dimensional changes of denture bases made from different resins after different storage periods. For this purpose, 25 sets of plaster models/resin bases were prepared using 4 acrylic resins submitted to two types of polymerization: 1- QC-20 submitted to polymerization by microwave energy; 2- QC-20 submitted to polymerization by water hot bath; 3- Vipi Cril submitted to polymerization by water hot bath; 4- Vipi Wave submitted to polymerization by microwave energy; and 5- Onda Cryl submitted to polymerization by microwave energy. After polymerization, the specimens were sectioned for accuracy readings using a comparison microscope. Readings were taken at 3 points: the crests of the right (A) and left (B) ridges, and the median region of the palate, in 4 different periods. The data obtained were submitted to two-way ANOVA and Tukey's test at 5 percent significance level. The greatest distortions were found in the posterior palatal region of the base (M), with statistically significant difference (p<0.05) for the studied resins. All acrylic resins presented dimensional changes and the storage period influenced these alterations.

O objetivo deste estudo foi avaliar a alteração dimensional de bases de prótese total confeccionadas com diferentes resinas após diferentes períodos de armazenagem. Para isso foram confeccionados 25 conjuntos modelo de gesso/base de resina, utilizando-se quatro resinas acrílicas: QC-20 submetida à polimerização convencional e por energia de microondas, Vip Cril submetida à polimerização convencional, Vip Wave e Onda Cryl submetida à polimerização por energia de microondas. Após a polimerização, as amostras foram seccionadas para realização de leituras de adaptação com auxílio de um microscópio comparador. As leituras foram realizadas em três pontos: crista do rebordo direito (A) e esquerdo (B), e região mediana do palato, em quatro diferentes períodos. Os resultados foram submetidos à análise de variância e ao teste de Tukey com nível de significância de 5 por cento. A pior adaptação foi verificada na região palatina posterior da base (M) com diferença estatisticamente significante (p<0,05) para as resinas estudadas. Todas as bases de resinas apresentaram alteração dimensional e o período de armazenagem foi um fator que influenciou essa alteração.

A comparative study on the dimensional change of the different denture bases / 대한치과보철학회지

STATEMENT OF PROBLEM: Acrylic resin is most commonly used for denture bases. However, acrylic resin has week points of volumetric shrinkage during polymerization that reduces denture fit. The expandability of POSS (Polyhedral Oligomeric Silsesquioxane) containing polymer could be expected to reduce the polymerization shrinkage of denture bases and would increase the adaptability of the denture to the tissue. PURPOSE: The purpose of this study was to compare the dimensional stability in the conventional acrylic resin base, POSS-containing acrylic resin base, and metal bases. MATERIALS AND METHODS: Thirty six maxillary edentulous casts and dentures of different base were fabricated. Tooth movement and tissue contour change of denture after processing (resin curing, deflasking, decasting and finishing without polishing) and immersion in artificial saliva at 37 degrees C for 1 week and 4 weeks were measured using digital measuring microscope and threedimensional laser scanner. RESULTS: The results were as follows: 1. The conventional resin group showed significant (p<0.01) dimensional change throughout the procedure (processing and immersion in artificial saliva). 2. After processing, the metal group and POSS resin group showed lower linear and 3-dimensional change than conventional resin group (p<0.01). 3. There was no statistically significant linear and 3-dimensional change after immersion for 1 week and 4 weeks in metal and POSS resin group. 4. In all groups, the midline and alveolar ridge crest area presented smaller 3-dimensional change compared with vestibule and posterior palatal seal area after processing and soaking in artificial saliva for 1 week and 4 weeks (p<0.01). CONCLUSION: In this study, a reinforced acrylic-based resin with POSS showed good dimensional stability.

Influence of soft tissue and bone thickness on the dimensional change of peri-implant soft tissues: A clinical follow-up study / 대한치주과학회지

The aim of this study was to investigate the influence of peri-implant soft tissue and bone thickness on the early dimensional change of peri-implant soft tissue. Seventy-seven non-submerged implants of 39 patients which had been loaded more than 6 months were selected for the study. Following clinical parameters were measured; bucco-lingual bone width of the alveolar bone for implant placement before implant surgery; distance between implant shoulder and the first bone/implant contact at the surgery; presence of plaque, probing depth, bleeding on probing, width of keratinized mucosa, mucosa thickness, distance between implant shoulder and peri-implant mucosa, crown margin location at follow-up examination. The results showed that distance between implant shoulder and peri-implant mucosa (DIM) was correlated with probing depth and width of keratinized mucosa (p < 0.05). In addition, mucosa thickness was also correlated with probing depth (p<0.05). However, the bone width of alveolar bone and soft tissue thickness were not found to be correlated with DIM. It is important to understand the meaning of peri-implant tissue dimension in relation to dimensional changes of peri-implant soft tissue which designates appearance of implant-supported restorations. Future study is needed to elucidate the significance of the buccal bone thickness and soft tissue thickness with respect to the change of peri-implant soft tissue margin with the use of an instrument capable of measuring buccal bone thickness directly.

Agar-alginate combined impression technique and dimensional change resulting from idophor disinfection / 대한치과보철학회지

STATEMENT OF PROBLEM: Because dental impression can be a cross-infection source, disinfection, such as immersion disinfection is nessecary. However, the disinfection process may change the volume of the impression cast. PURPOSE: The purpose of this study is to find out the effects on dimensional change of different storage times and methods, of agar-alginate impression when immersed in a 5% idophor disinfectant. MATERIAL AND METHODS: An agar-alginate impression was made from a mandible model and then was disinfected and stored according the experimental conditions and a stone model was produced. Measurements were taken between reference points on the original mandible model and they were compared to measurements taken between reference points on the stone model. The study was divided into 4 groups. In group 1, the impression was stored in a 100% humidor for 30 minutes, 1 hour, 2 hours, 3 hours, 4 hours, 6 hours, 12 hours and 24 hours and stone models were made at each time. In group 2, the impression was immersed in 5% idophor disinfectant and then stored in a 100% humidor for the same length of times as group 1, and stone models were made at each time. In group 3, the impression was stored in extend-A-pourR, a special storage solution for 30 minutes, 1 hour, 2 hours, 3 hours, 4 hours, 6 hours, 12 hours, 24 hours 3 days, and 7 days and stone models were made at each time. In group 4, the impression was immersed in 5% idophor disinfectant and then stored in stored in extend-A-pourR, a special storage solution for the same length of times as group 3, and stone models were made at each time. 5 impressions and stone models were made at each time to make a total of 180. The Student-t test (P < .05) was used to do a statistical analysis of the measurements of the mandible model and stone models. The repeated-measure 2-way analysis of variance (P < .05) was used to do a statistical analysis of the difference in the 4 groups. RESULTS: The percent liner dimensional change was from 0.25+/-0.03% (group 1, 30 minutes) to 0.34+/-0.06% (group 4, 7 days). No significant change was noticed between the 4 groups. CONCLUSION: According to the above study, in both methods, least dimensional change was recorded when the storage times were short and in both methods, immersion in 5% idophor disinfectant did not effect dimensional change in the agar-alginate impression.