Clinical Evaluation of Wear Behavior of Human Enamel and Chipping of Veneered Zirconia against Monolithic Zirconia (Randomized Controlled Clinical Trial) / Avaliação clínica do comportamento de desgaste do esmalte humano e lascamento da zircônia estratificada contra a zircônia monolítica (ensaio clínico controlado randomizado)

Objective: To evaluate the wear behavior of human enamel and chipping of veneered and monolithic zirconia for posterior full coverage restorations. Material and methods: Thirty-four zirconia full coverage restorations (seventeen in each group) were fabricated. The patients were divided into two groups according to the type of zirconia used; group 1 (comparator group) veneered zirconia crowns and group 2 (intervention group) monolithic zirconia single crowns. All crowns were lab fabricated and polished. For opposing teeth wear measurements 3D non-contact profilometer was used where epoxy resin replicas were constructed for opposing arch immediately after crowns cementation, three, six and twelve months. Restoration chipping was measured using modified United States Public Health Services (USPHS) criteria. Results: All restorations were reported as alpha with no chipping. There was no statistically significant difference between (Group 1) and (Group 2) for wear test. Conclusion: Both monolithic and veneered restorations revealed satisfactory mechanical properties with no chipping after one year of clinical use. Wear of opposing enamel was clinically acceptable for both materials. (AU)

Objetivo: Avaliar o comportamento ao desgaste do esmalte humano e lascamento de zircônia estratificada e monolítica para coroas totais posteriores. Material e métodos: Trinta e quatro coroas totais de zircônia (dezessete em cada grupo) foram fabricadas. Os pacientes foram divididos em dois grupos de acordo com o tipo de zircônia utilizada; grupo 1 (grupo controle) coroas de zircônia estratificada e grupo 2 (grupo de intervenção) coroas de zircônia monolítica. Todas as coroas foram fabricadas e polidas em laboratório. Para medidas de desgaste de dentes opostos, foi utilizado um perfilômetro 3D sem contato, onde réplicas de resina epóxi foram construídas para o arco oposto imediatamente após a cimentação das coroas, três, seis e doze meses após. O lascamento da restauração foi medido usando critérios modificados dos Serviços de Saúde Pública dos Estados Unidos (USPHS). Resultados: Todas as restaurações foram relatadas como alfa sem lascamento. Não houve diferença estatisticamente significativa entre (Grupo 1) e (Grupo 2) para o teste de desgaste. Conclusão: Ambas as coroas monolíticas e estratificadas revelaram propriedades mecânicas satisfatórias sem lascamento após um ano de uso clínico. O desgaste do esmalte oposto foi clinicamente aceitável para ambos os materiais. (AU)

Antinutritional Factors Reduction from Cassava (Manihot esculenta Crantz) Roots by Grating or Chipping Processing Technique in Mtwara Tanzania

Regular intake of diets high in cyanogenic amount in iodine deficiency areas with limited sulfur supply diets have been associated with the development of hypothyroidism, goiter and cretinism in young and adult populations. This study aimed at the investigation of the suitable processing technique for the production of high-quality cassava flour (HQCF) with acceptable consumption level of cyanide residues from different cassava varieties available at Mmongo village in Mtwara region. Grating technique was used to produce wet and dried cassava grits, whereas chipping technique produced wet and dried cassava chips. The wet and dried cassava products were all produced in a single day and under the same environmental conditions. The results showed that the hydrogen cyanide (HCN) in fresh cassava roots was 62.18–139.28 mg HCN/kg. Upon processing, the cyanide was lower (P<0.05) in wet cassava grits 24.27–76.74 mg HCN/Kg but higher in wet cassava chips 44.81–92.57 mg HCN/kg. After sun drying, the HCN retention was higher in dried cassava chips (10.7–14.2%) and lower in dried cassava grits (7.3–9.1%). Grating, efficiently reduced HCN from bitter cassava roots to the level within the WHO/FAO recommended safe limit (10 mg HCN/kg) as chipping only suite for sweet cassava roots. Therefore, HQCF can be nutritionally strategic cassava product consumed regularly and during food shortage without causing potential health problems even in iodine deficiency areas.

Repair bond strength of resin composite to bilayer dental ceramics

PURPOSE: The purpose of this study was to investigate the effect of various surface treatments (ST) on the shear bond strength of resin composite to three bilayer dental ceramics made by CAD/CAM and two veneering ceramics. MATERIALS AND METHODS: Three different bilayer dental ceramics and two different veneering ceramics were used (Group A: IPS e.max CAD+IPS e.max Ceram; Group B: IPS e.max ZirCAD+IPS e.max Ceram, Group C: Vita Suprinity+Vita VM11; Group D: IPS e.max Ceram; Group E: Vita VM11). All groups were divided into eight subgroups according to the ST. Then, all test specimens were repaired with a nano hybrid resin composite. Half of the test specimens were subjected to thermocycling procedure and the other half was stored in distilled water at 37℃. Shear bond strength tests for all test specimens were carried out with a universal testing machine. RESULTS: There were statistically significant differences among the tested surface treatments within the all tested fracture types (P .00125). CONCLUSION: This study revealed that HF etching for glass ceramics and sandblasting for zirconia ceramics were adequate for repair of all ceramic restorations. The effect of ceramic type exposed on the fracture area was not significant on the repair bond strength of resin composites to different ceramic types.

Comparison of traditional and simplified methods for repairing CAD/CAM feldspathic ceramics

PURPOSE: To evaluate the adhesion to CAD/CAM feldspathic blocks by failure analysis and shear bond strength test (SBSt) of different restorative systems and different surface treatments, for purpose of moderate chipping repair. MATERIALS AND METHODS: A self-adhering flowable composite (Vertise Flow, Kerr) containing bi-functional phosphate monomers and a conventional flowable resin composite (Premise Flow, Kerr) applied with and without adhesive system (Optibond Solo Plus, Kerr) were combined with three different surface treatments (Hydrofluoric Acid Etching, Sandblasting, combination of both) for repairing feldspathic ceramics. Two commercial systems for ceramic repairing were tested as controls (Porcelain Repair Kit, Ultradent, and CoJet System, 3M). SBSt was performed and failure mode was evaluated using a digital microscope. A One-Way ANOVA (Tukey test for post hoc) was applied to the SBSt data and the Fisher's Exact Test was applied to the failure analysis data. RESULTS: The use of resin systems containing bi-functional phosphate monomers combined with hydrofluoric acid etching of the ceramic surface gave the highest values in terms of bond strength and of more favorable failure modalities. CONCLUSION: The simplified repairing method based on self-adhering flowable resin combined with the use of hydrofluoric acid etching showed high bond strength values and a favorable failure mode. Repairing of ceramic chipping with a self-adhering flowable resin associated with hydrofluoric acid etching showed high bond strength with a less time consuming and technique-sensitive procedure compared to standard procedure.

The effet of cooling rate on the residual stresses in the veneer ceramics of zirconia-ceramic restorations: a literature review / 대한치과보철학회지

Nowadays, dental zirconia is widely used as a framework material for a fixed dental prosthesis as well as a single restoration. However, clinical studies have reported high incidence of veneer chipping of zirconia-ceramic restorations compared to that of metal-ceramics. Several factors were raised as the possible causes of veneer ceramic chipping, however, it is still in debate. Recently, residual stresses in the veneer ceramics after cooling process gathers attention as one possible cause of chipping and many studies reported that the rate of cooling significantly influenced the types and the amount of residual stress. The purpose of current review was to briefly describe the effect of cooling rate on the residual stress in zirconia-ceramics. It was also described that the different behavior of residual stress between zirconia-ceramics and metal-ceramics following different cooling rate.

Bond strength of veneer ceramic and zirconia cores with different surface modifications after microwave sintering

PURPOSE: To evaluate the effects of surface treatments on shear bond strength (SBS) between microwave and conventionally sintered zirconia core/veneers. MATERIALS AND METHODS: 96 disc shaped Noritake Alliance zirconia specimens were fabricated using YenaDent CAM unit and were divided in 2 groups with respect to microwave or conventional methods (n=48/group). Surface roughness (Ra) evaluation was made with a profilometer on randomly selected microwave (n=10) and conventionally sintered (n=10) cores. Specimens were then assessed into 4 subgroups according to surface treatments applied (n=12/group). Groups for microwave (M) and conventionally (C) sintered core specimens were as follows; M(C),C(C): untreated (control group), M1,C1:Al2O3 sandblasting, M2,C2:liner, M3,C3:Al2O3 sandblasting followed by liner. Veneer ceramic was fired on zirconia cores and specimens were thermocycled (6000 cycles between 5degrees-55degrees C). All specimens were subjected to SBS test using a universal testing machine at 0.5 mm/min, failure were evaluated under an optical microscope. Data were statistically analyzed using Shapiro Wilk, Levene, Post-hoc Tukey HSD and Student's t tests, Two-Way-Variance-Analysis and One-Way-Variance-Analysis (alpha=.05). RESULTS: Conventionally sintered specimens (1.06 +/- 0.32 microm) showed rougher surfaces compared to microwave sintered ones (0.76 +/- 0.32 microm)(P=.046), however, no correlation was found between SBS and surface roughness (r=-0.109, P=.658). The statistical comparison of the shear bond strengths of C3 and C1 group (P=.015); C(C) and M(C) group (P=.004) and C3 and M3 group presented statistically higher (P=.005) values. While adhesive failure was not seen in any of the groups, cohesive and combined patterns were seen in all groups. CONCLUSION: Based on the results of this in-vitro study, Al2O3-sandblasting followed by liner application on conventionally sintered zirconia cores may be preferred to enhance bond strength.

Causas de fractura o defragmentación de la cerámica de recubrimiento (chipping) en restauraciones de zirconio / Chipping causes in zirconia-ceramic restorations

El chipping es una problema que se presenta en las restauraciones de cerámica sobre zirconio. el objetivo de este trabajo es revisar las causas de esta falla. a tal fin, se seleccionaronpublicaciones en Pub Med y revistas científicas de alto impacto desde el año 2007 a 2010, incluyendo estudios in vitro e in vivo. Mediante lectura y análisis exhaustivo de los artículos, se planteó a manera de resultados, la frecuencia del problema y los factores que predisponen al chipping de la cerámica sobre el zirconio. Se discute acerca de los hallazgos en pruebas in vitro y con elementos finitos de las propiedades y comportamiento de dichos materiales, tanto como su correlación con el desempeño clínico de las restauraciones. tras esta revisión, se intenta evaluar el impacto del problema en la situación clínica y aclarar los factores que predisponen, odirectamente provocan, la falla cohesiva de las restauraciones cerámica sobre zirconio.

Clinical Analysis and Material Selection of Tension-free Hernia Repair in 130 Cases / 医学研究杂志

Objective To discuss the operation style of filling,film-style,three-dimensional double-layer mesh tension-free for hernia and the repair materials,the selectlon of surgical operation style for reducing recurrence.Methods We used the style of plug-and-chip,two-dimensional mesh tension-free hernia repair for the treatment of 130 cases of inguinal hernia patients.Results In 130 cases of patients with 1~5 years of follow-up,there was no recurrence.Conclusion A reasonable choice of repair materials and improving the surgical operation can be effective in reducing recurrence.