Effect of chemical, microwave irradiation, steam autoclave, ultraviolet light radiation, ozone and electrolyzed oxidizing water disinfection on properties of impression materials: A systematic review and meta-analysis study.

OBJECTIVES: The objective of this systematic review and meta-analysis study was to identify the different disinfection methods and materials and the existing evidence on their effect on properties of the different impression materials. MATERIAL AND METHODS: An electronic search of MEDLINE (PubMed), Science Direct, and Google Scholar databases was performed to retrieve related English-language articles published between January 2000 and July 2019. Available studies with search terms such as: Impression disinfection, disinfection method, impression dimensional stability and impression wettability were used. The selected articles were reviewed by screening their titles and abstracts and full text. Finally, a total of 70 articles were considered relevant and were included in this study. RESULTS: Extensive studies were conducted to determine the effect of the different disinfection methods and materials on the properties of the different impression materials such as dimensional stability, wettability and surface roughness. While some studies reported significant changes in the properties of the impression materials, others reported either no changes or minor insignificant effects. CONCLUSIONS: Some studies reported significant changes in the properties of the impression materials as a result of using different disinfection methods, whereas others reported either minor insignificant or no changes. Although the findings of the studies were controversial, care should be taken to avoid distortion of impressions and loss of their surface details that can adversely affect the fitting accuracy of the restorations. Therefore, better designed and standardized studies are needed to evaluate the effect of different commonly used disinfectants on properties of impression materials. Moreover, manufacturers should be encouraged to recommend specific disinfection methods and materials for disinfecting the impression materials to ensure their optimal accuracy.

Two novel SNPs in genes involved in immune response and their association with mandibular residual ridge resorption.

"Residual ridge resorption" (RRR) is a multifactorial condition involving bone resorption of the residual ridge. We investigated 10 single nucleotide polymorphisms (SNPs) in seven genes with the aim of identifying the genetic factors associated with RRR susceptibility. The study group included 96 RRR patients and 96 controls. Age at first edentulism, duration of edentulism, and bone height were recorded. Saliva was collected from the subjects for DNA extraction. Genotype analysis was performed on the 'SequenomMassARRAYiPLEX'. The genotype and allele frequencies calculated in patients and controls were compared. We found that rs1800896 in the IL10 gene and rs5743289 in NOD2 gene showed significant association with RRR. Within the RRR group, genotypes for each SNP were separated, and we observed that the age at first edentulism and bone height showed variations in the different genotypes of the ten studied SNPs. This study showed an association between SNPs in IL10 and NOD2 genes. It also revealed that the genotypes of the different SNPs influence bone resorption and health. Additionally, age at first edentulism and bone height were much lower in some genotypes. This study demonstrates the need for larger multicenter trials to confirm these findings. Finally, we suggest that the results of this study may be utilized for developing novel genetic diagnostic tests and for identifying Saudi individuals who may be more susceptible to RRR development following dental extraction.

Effect of Intraoral Mechanical Cleaning Techniques on Bond Strength of Cast Crowns to Metal Cores.

PURPOSE: To evaluate the effect of cleaning of metal cores from provisional cement, using an intraoral airborne-particle abrasion method, on the bond strength of permanent resin cement with cast crowns to cores. MATERIALS AND METHODS: Thirty stainless steel models of a standard complete crown tooth preparation were fabricated. Thirty Type III gold crowns were fabricated. Each cast crown corresponded to one stainless steel crown preparation model. All crowns were cemented with noneugenol zinc oxide cement and stored for 7 days at 37°C. All crowns were debonded, and the cement was cleaned with airborne-particle abrasion using 50 µm aluminum oxide at 4.1 bar (0.41 MPa) followed by ultrasonic cleaning. Based on the mechanical cleaning technique of the remaining provisional cement on surfaces of cast cores, specimens were equally divided into 3 groups: hand cleaning (HC) with a dental excavator, hand cleaning followed by polishing using a brush and pumice (BP), and hand cleaning followed by intraoral airborne-particle abrasion (APA). All crowns were then cemented to their corresponding cores using universal resin cement. All crowns were stored for 7 days at 37°C. An Instron universal testing machine was used to record the bond strength of crowns. RESULTS: Airborne-particle abrasion method for intraoral mechanical cleaning revealed a statistically significantly higher bond strength compared to the other two methods. CONCLUSIONS: When comparing the three methods of provisional cement cleaning from metal cores, airborne-particle abrasion resulted in the highest bond strength for cast crowns.

Mandibular residual ridge height in relation to age, gender and duration of edentulism in a Saudi population: A clinical and radiographic study.

PURPOSE: The purpose of this clinical and radiographic study was to evaluate the effect of age, gender and duration of edentulism on the amount of mandibular residual ridge resorption in a Saudi population. MATERIAL AND METHODS: Partially and completely edentulous Saudi patients (50 male and 64 female) attending the outpatient clinics at College of Dentistry, King Saud University, Riyadh, Saudi Arabia were included. Current age, gender of subjects and date of start of edentulism were recorded. Digital panoramic dental radiograph less than 1 year old of each patient was examined. The height of edentulous mandible was measured as described in the American College of Prosthodontists Prosthodontic Diagnostic Index (PDI) classification. Students t-test and ANOVA post hoc tests, Pearson's correlation coefficient (r) and chi square (χ2) analysis were performed as indicated. Level of statistical significance was set at 0.05. RESULTS: Male patients showed a significantly greater mandibular bone height compared to female patients. Age and bone height were statistically significantly negatively correlated (p = 0.0001). However, age and mandibular bone height in only male patients was negatively correlated and reached statistical significance (p = 0.001) A negative correlation was observed between duration of edentulism and mandibular bone height in both genders, but was not statistically significant (p > 0.05). CONCLUSIONS: In a Saudi population, men have greater mandibular bone height than women and also exhibit a negative correlation between age and mandibular bone height that is statistically significant. In contrast, women exhibited a negative correlation between age and mandibular bone height, but was not statistically significant.

Effect of 0.5% glutaraldehyde disinfection on surface wettability of elastomeric impression materials.

PURPOSE: The purpose of this in-vitro study was to evaluate the effect of 0.5% glutaraldehyde spray disinfection on surface wettability of vinyl polysiloxane and polyether impression materials. METHODS AND MATERIALS: Thirty-six specimens were prepared of vinyl polysiloxane-light (VPL), vinyl polysiloxane-regular (VPR) viscosity and polyether-monophase (PE) impression materials according to manufacturer's recommendations. Specimens of each material were equally divided into control and experimental groups. All specimens were washed with water, dried and stored in closed containers. Specimens of experimental groups were sprayed with 0.5% glutaraldehyde disinfectant. The disinfectant was allowed to be in contact with the impression surface for 10 min. Contact angle was measured using a Contact Angle Goniometer at 0.5, 1 and 2 min after water drop contact with surfaces of impression materials. Five measurements at five different areas at each impression surface were recorded. A statistical analysis was done using Two-way repeated measures ANOVA and multiple comparison Tukey's Post-hoc tests. RESULTS: All 0.5% glutaraldehyde-disinfected impression materials showed lower contact angle measurements than non-disinfected ones. Contact angle measurements of PE were much lower than those of VPL and VPR impression materials. However, there was a statistically significant difference of contact angle measurements between the three impression materials (p = 0.000). Contact angle measurements of all groups significantly decreased as the time was increased (p = 0.000). CONCLUSION: Disinfection of the tested impression materials with 0.5% glutaraldehyde improved their wettability. Glutaraldehyde acted like a surface reducing agent (surfactant) that improved wetting potential of the impression materials.

A comparative evaluation of the effect of phototherapy of fiber post on its bond strength to dental composite.

The aim of the study was to evaluate the effect of diode laser as a phototherapy on surface treatment of fiber post and its bond strength to resin core build-up material. In this in-vitro study fifty fiber post of 1 mm tip-diameter and 20 mm length were used. The posts were mounted and randomly divided into 5 groups (n = 10) according to different surface treatment methods i.e. Group 1: Control, Group 2: Application of 37% Phosphoric Acid, Group 3: Treated with 40% H2O2, Group 4: Sandblasted with 50 µm aluminium oxide particles and Group 5: treated with diode laser. In all specimens including control, a cylinder of resin composite around the fiber post was made. All Specimens were mounted in a universal testing machine. Push-out test was performed and bond strengths were calculated. Using analysis of variance (ANOVA) and post hoc Tukey multiple comparisons test, means of push out bond strength were compared among the study groups. The highest bond strength was shown among Sandblasted [50 µm, Aluminium Oxide (Al2O3)] group [139.86] and the lowest push-out bond strength was observed in Control specimens [75.73]. The bond strength values of fiber post treated with Diode laser [100.81] and 40% H2O2 [105.64] were comparable.