Although numerous studies have demonstrated the benefits of incorporating filler particles into maxillofacial silicone elastomer (MFPSE), a review of the types, concentrations and effectiveness of the particles themselves was lacking. The purpose of this systematic review and meta-analysis was to review the effect of different types of filler particles on the mechanical properties of MFPSE. The properties in question were (1) tensile strength, (2) tear strength, (3) hardness, and (4) elongation at break. The findings of this study can assist operators, technicians and clinicians in making relevant decisions regarding which type of fillers to incorporate based on their needs. The systematic review was performed according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. A total of 26 original articles from 1970 to 2019 were selected from the databases, based on predefined eligibility criteria by two reviewers. The meta-analyses of nine papers were carried out by extracting data from the systematic review based on scoring criteria and processed using Cochrane Review Manager 5.3. Overall, there were significant differences favoring filler particles when incorporated into MFPSE. Nano fillers (69.23% of all studies) demonstrated superior comparative outcomes for tensile strength (P < 0.0001), tear strength (P < 0.00001), hardness (P < 0.00001) and elongation at break (P < 0.00001) when compared to micro fillers (30.76% of all studies). Micro fillers demonstrated inconsistent outcomes in mechanical properties, and meta-analysis of elongation at break argued against (P < 0.01) their use. Current findings suggest that 1.5% ZrSiO₄, 3% SiO₂, 1.5% Y₂O₃, 2–6% TiO₂, 2–2.5% ZnO, 2–2.5% CeO₂, 0.5% TiSiO₄ and 1% Ag-Zn Zeolite can be used to reinforce MFPSE, and help the materials better withstand mechanical degradation.

The aim of this study was to evaluate published data regarding riboflavin (RF) as a cross-linker for improved adhesive bond strength to dentin and to analyze previous studies for optimal concentration of riboflavin range suitable for dentin bond. Saliva and distilled water were used as storage media and aging time was 24 h and 6 months. Results of meta-analysis were synthesized using a statistical method of inverse variance in random effects with a 95% Confidence Interval (CI). Cochrane review manager 5.4.1 was used to determine results of the meta-analysis. In total, 3172 articles were found from search databases “PubMed”, “Scopus”, and “Google Scholar”. Six of the fifteen studies were eligible for meta-analysis. Micro tensile strength shows significant improvement with the addition of riboflavin (p < 0.05) compared to without the addition of riboflavin from with 95% CI. A significant difference has been found in micro tensile bond strength between use of the riboflavin cross-linker and without use of the riboflavin crosslinker in the dentin adhesive system. With a 95% confidence interval (CI), the I² for micro tensile strength was 89% with strong heterogeneity, Chi² = 44.76, df = 5 (p < 0.00001), and overall effect size is Z = 2.22 (p = 0.03) after immediate aging. Chiang et al. 2013 shows maximum mean differences which is 38.50 [17.93–59.07]. After 6 months of aging in distilled water or artificial saliva micro tensile bond strength has been increased with the addition of riboflavin (p < 0.05). It can be clearly seen that pooled effect and 95% CI did not cross the line of no effect. With a 95% confidence interval (CI), the I² for micro tensile strength was 96% with strong heterogeneity, Chi² = 117.56, df = 5 (p < 0.00001), and overall effect size is Z = 2.30 (p = 0.02). Subgroup analysis proved a similar effect of distilled water and artificial saliva as storage media on micro tensile bond strength after incorporating riboflavin as a collagen crosslinker. An artificial saliva aged forest plot also showed considerable heterogeneity with I² = 96%; Tau² = 257.32; Chi² = 94.37; df = 2 (p < 0.00001); test for overall effect, Z = 1.06 (p = 0.29). Riboflavin prior to or with bonding is recommended to improve the bonding of different adhesive systems.

Objective: The virtual cone beam computed tomography–derived 3-dimensional model was compared with the scanned conventional model used in the fabrication of a palatal obturator for a patient with a large palatal defect. Design: A digitally derived 3-dimensional maxillary model incorporating the palatal defect was generated from the patient’s existing cone beam computerized tomography data and compared with the scanned cast from the conventional impression for linear dimensions, area, and volume. The digitally derived cast was 3-dimensionally printed and the obturator fabricated using traditional techniques. Similarly, an obturator was fabricated from the conventional cast and the fit of both final obturator bulbs were compared in vivo. Results: The digitally derived model produced more accurate volumes and surface areas within the defect. The defect margins and peripheries were overestimated which was reflected clinically. Conclusion: The digitally derived model provided advantages in the fabrication of the palatal obturator; however, further clinical research is required to refine consistency.

Purpose. To evaluate the influence of edible liquids on the characteristic properties of 3D printable materials compared to conventionally used dental resin acrylic. Method. Dental polymethyl methacrylate (PMMA) specimens were fabricated from preformed molds while polylactic acid (PLA) and polyethylene terephthalate glycol (PETG) specimens were 3D printed using fused deposition modelling at 0.1 mm layer thickness. All specimen forms adhered to ISO 37:2017 and ISO 604:2002 specifications. Specimens underwent controlled immersion for 180 hr into different media (no immersion (control), oil, soda, milk, and caffeine). Changes in mass (g), plastic deformity (N/mm²), ultimate tensile stress (N), flexural deformity (N/mm²), and break force (N) were evaluated using analysis of variance. Results. There was an increase in mass for all specimens following immersion with significant interactions between immersion media and the materials. The materials exhibited significant differences in plastic deformity (F (df) = 156.632(2), P < 0.001), ultimate tensile stress (F (df) = 109.521(2), P < 0.001), and break force (F (df) = 319.785 (2), P < 0.001) with no significant interactions with immersion media (P > 0.05) on both accounts. Materials showed no significant differences in flexural deformity (F (df) = 2.693(2), P = 0.074) but with significant interactions (F (df) = 4.984(8), P < 0.001) between acrylic and immersion media. Conclusion. Commercially available 3D printable PLA and PETG filaments printed at 0.1 mm thickness possess approximately half the mechanical resilience as dental PMMA with comparable flexural deformity after exposure to edible liquids.

Objective: To investigate the compressive, dimensional, and antimicrobial properties of thermoplastic Acrylonitrile Butadiene Styrene (ABS) 3D printed hollow blocks following chemical disinfection. Methods: Forty-two 3D printed ABS cubes were immersed in tap water, 0.12% chlorhexidine gluconate, 3% hydrogen peroxide, 5% sodium bicarbonate, 0.5% sodium hypochlorite, and commercial Potassium Caroate (Polident) for 28 days (4 cycles). Linear Outer (OM) and Inner (IM) dimensions, Root Mean Square (RMS), and mass were recorded before and after each immersion cycle. An additional set of seven cubes was untreated and served as a control. Fourier transform infrared spectroscopy (FTIR) was executed on one randomly selected sample from each group before and after immersion. Following the completion of the immersion cycles, an evaluation of compressive strength was performed using a universal testing machine. Subsequently, from each group, a single ABS cube was randomly selected for the introduction of Streptococcus mutans and Candida albicans, followed by a 14-day incubation period with Scanning Electron Microscope (SEM) evaluation. Results: There were no significant differences (p > 0.05) between OM, IM, and compressive strength measurements (F = 1.036, p = 0.443) across all groups. RMS values increased for OM and decreased for IM. Notably, cubes that underwent immersion in a 0.12% chlorhexidine gluconate solution displayed considerable changes in mass (p < 0.05), exhibiting a low positive correlation (ρ = 0.339). The 0.12% chlorhexidine gluconate group exhibited the emergence of a new OH peak (3000–3500) in FTIR, whereas the 3% hydrogen peroxide group experienced the disappearance of the styrene peak (1300–1500). Exposure of ABS to C. albicans and S. mutans demonstrated clear surfaces under SEM with 0.12% chlorhexidine gluconate, 0.5% sodium hypochlorite, and Polident. Conclusions: Disinfection with 0.5% sodium hypochlorite and Potassium Caroate produced minimal mechanical changes and resisted growth of C. albicans and S. mutans. 0.12% chlorhexidine gluconate and 3% hydrogen peroxide altered dimensional and chemical compositions of 3D printed ABS following disinfection.

Purpose: For making denture in maxillectomy cases is very difficult and challenging to get the retention tomake the denture stable in its position during functioning. This case report describes a clinical condition inwhich patient was treated with a maxillary obturator with zygomatic suspension wiring due to insufficientretention in the palate. Materials and Methods: A 63-year-old patient had gone to a subtotal maxillectomybecause following myofibroblastic sarcoma andwas issued with bilateral circum-zygomatic wiring hooksimmediately after surgery. The patient had less than a third of their alveolar ridge remaining and did notprovide sufficient retention on its own. The wires were used for the retention because natural retentioncould not get due to inadequate maxillary ridge. While the denture was being fabricated, a temporaryfeeding plate was provisioned to the patient. Counter hooks were implemented on the definitive upperdenture, posterior to molars, to attach to the zygomatic suspension hook. Final upper denture was furtherreinforced with denture adhesive on it. A lower denture was also fabricated for the said case followingconventional protocols of jaw relation determination. Results: The obturator provided with adequate sealand leak proof phonetics. The zygomatic wiring coupled with denture adhesive were sufficient to provideadequate retention. Conclusion: Zygomatic suspension wires coupled with counter hooked obturatorprosthesis provide rehabilitation of patients with palatal defects with inadequate maxillary arch forretention.However long-term repeated use of such wires might expose the patient to secondary infectionsand should be kept in consideration Clinical Significance: Circum-zygomatic suspension wiring providesufficient retention to sustain the upper obturator prosthesis in place. However, the retention was stillinadequate, so denture adhesives were used to make it more stable. Bangladesh Journal of Medical Science Vol.19(3) 2020 p.582-585