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Esthetic orthodontic brackets available commercially are made of different ceramic materials: alumina, which is most commonly used, is either monocrystalline or polycrystalline and zirconia is least commonly used. These ceramic brackets showed significant drawback which limited their wide use by the orthodontic clinicians. They are associated with numerous problems; one of the major problems is excessive abrasion of opposing dentition and iatrogenic enamel damage when debonding, besides their opaque appearance. Objectives: To fabricate orthodontic brackets using a new esthetic interpenetrating phase ceramic and composite resin via CAD/CAM technology and evaluate their mechanical properties. To fabricate resin-infiltrated-spinel material and evaluate its optical and mechanical properties for use as an orthodontic bracket material. Materials and Methods: A CAD/CAM milling machine (CEREC Compact inLab, Dentsply-Sirona) was used to mill brackets with a 0.018"×0.025" slot from Vita-Enamic interpenetrating phase ceramic (Vita Zahnfabrik) and Cerasmart (GC America) composite resin block. The brackets were subjected to separate tests (torque, tipping and sliding) using a universal testing machine. The average moments necessary to fracture the brackets and the average frictional forces were determined and compared to commercially available zirconia brackets (Cercon ZirBra, Dentsply-Sirona) and alumina brackets (Ovation C, Dentsply-Sirona GAC). Additionally, Avex CX2 polycrystalline alumina (Opal Orthodontics) with a slot size 0.022"×0.028" was included in the test as well. Furthermore, MG-203 spinel powder was dry-pressed into multiple blocks, sintered at different temperatures and then infiltrated with resin. Densities at different stages were measured and recorded for comparison. Blocks were cut into disks of different thicknesses, and then tested for optical and mechanical properties. Results: The Enamic and Cerasmart brackets evaluated in this study presented adequate fracture strength compared to that necessary for torque and tipping movement reported in the literature. In addition, it demonstrated acceptable frictional behavior comparable to zirconia and polycrystalline alumina brackets. As the sintering temperature of spinel matrix increased, the fracture strength and transmission increased as well. Conclusions: Vita-Enamic and Cerasmart brackets were sufficiently strong to withstand the commonly accepted magnitudes of effectively torquing and tipping maxillary incisors dental movement without fracturing. Optical and mechanical properties of resin-infused spinel were enhanced by increasing sintering temperatures. / 2023-03-02T00:00:00Z

OBJECTIVES: To test and compare the effects of thermocycling, different bilayer material combinations, and different core/veneer material combinations on shear bond strength, flexural strength, and failure load of different dental restorative materials. METHODS: In this in-vitro study, 369 specimens were prepared from four materials; PEEK (Juvora), Vita Enamic, MarkII, and InCoris (Sirona). 144 specimens were divided into 12 groups and sectioned into plates (frameworks) and rods (veneers) for the shear bond strength test. The final dimension of each plate was about 18mm in length, 2mm thick, and 12mm in width. While the rods were core drilled to have a final diameter of 3.48mm. All plates and rods underwent surface treatment before bonding with adhesive resin (3M RelyX Ultimate), half of the specimens were thermal aged with 5,000 cycles before a shear bond strength test was performed on all specimens. 225 specimens were sectioned into bars for bilayer flexural strength test and load to failure analysis. The final dimension of the bars was 18mm in length, 2mm thickness, and 4mm width, bars were assigned into groups of tension materials and compression materials to be bonded together as a bilayer bar structure. Half of the bilayer bars underwent thermal aging. All bilayer and monolayer bars were tested for flexural strength, load to failures values were also analyzed as well as the mode of failures. RESULTS: The results of this study show that Enamic groups (EN/MKII) showed the highest shear bond strength (SBS) followed by Zirconia groups (Zr/En, Zr/MKII). PEEK groups show the lowest SBS values among the tested groups. Thermal aging did not affect SBS specimens except for Zr/En group where it decreases the SBS values. There was a significant difference in bilayer flexural strength and failure loads of Zirconia groups (Zr/En, Zr/MKII) were higher than other groups. PEEK groups (PEEK/EN, PEEK/MKII, PEEK/Zr) showed the lowest FS bilayer and load to failure values. CONCLUSION: SBS to PEEK was lower as compared to the other tested groups. Materials in tension and the adhesive interface layer significantly impact the bilayer flexural strength and failure load values.

Introduction: Implant placement as a means of tooth replacement has increasingly become the gold standard in patient treatment. In cases involving the maxillary posterior site development and implant placement, the clinician must be aware of maxillary sinus anatomy. Lateral wall maxillary sinus augmentation technique was utilized to increase bone height and width for posterior region presented with atrophic ridges. The highest post-operative complication rate for lateral wall sinus augmentation technique is perforation of the maxillary sinus schneiderian membrane. Various risk factors such as smoking, sinusitis, sinus septa, sinus pathology, schneiderian membrane thickness, angle of sinus, etc. may lead to increased prevalence. Purpose: This study aims to evaluate the medial-inferior-lateral (MIL) sinus angle and its resultant relationship with schneiderian membrane perforation in the lateral wall sinus augmentation technique. This study also evaluates the association between schneiderian membrane thickness and perforation risk. Additional confounders including age, gender, ethnicity, and presence of dentition will also be examined. Materials and Methods: 783 cone beam computed tomography (CBCT) scans taken at the Temple University Kornberg School of Dentistry Department of Oral Maxillofacial Radiology between January 2005 and June 2022 were evaluated with Infinitt Software. Patients above 18 years old, had a pre-operative CBCT scans taken, and had a lateral wall sinus augmentation procedure completed were included in the study. In total, 55 CBCT satisfied the inclusion criteria. The MIL angle formed between the medial, inferior, and lateral walls of the sinus (MIL) were measured. The primary outcome variable is whether or not a perforation occurred during the execution of the lateral wall sinus augmentation procedure. Age, gender, ethnicity, schneiderian membrane thickness and dentition status were evaluated as potential confounders. A chi-squared test and fisher’s exact test were used to determine the association between MIL sinus angle and perforation of the membrane. A multivariable regression analysis was used to test the confounders of age, gender, ethnicity, dentition status, and schneiderian membrane thickness. The validity of the logistic regression model was evaluated by the Wald Test. 95% confidence intervals of perforation rates were calculated with normal approximation under binomial distribution assumption. Results: This study included 55 subjects subdivided by gender into 15 females and 40 males, and subdivided by ethnicity into 31 Caucasians, 6 African Americans, 15 Asians, and 3 Hispanics. 16 subjects had complete edentulism at the maxillary posterior region and 39 subjects presented with partial edentulism. The overall schneiderian membrane perforation rate was 63.64%. The perforation rate in MIL angles less than 60 degrees was 100%. The perforation rate in MIL angles between 60-90 degrees was 74.19%. The perforation rate in MIL angles greater than 90 degrees was 20.00%. There was a statically significant increase in rate of perforation across the three angle groups with more acute angles showing higher prevalence p < 7.656e-05. The perforation rate in schneiderian membrane thicknesses less than 1.5mm was 75.00% while the rate of perforation in schneiderian membrane thicknesses greater than 1.5mm was 34.78%. Perforation rate was found statistically significantly higher in female and Hispanic. The risk ratio for female gender was 1.30 95% CI (1.02-1.65) p < 0.01. The risk ratio for Hispanic ethnicity was 1.41 95% CI (1.00-1.99) p < 0.01. Conclusion: A statistically significant increase in maxillary sinus perforation incidence was found with lower MIL sinus angle. Schneiderian membrane thicknesses greater than 1.5mm had a lower perforation rate than schneiderian membrane thicknesses less than 1.5mm. Female and Hispanic contributed to a statistically higher chance of sinus perforation. Limitations of this study included lateral wall sinus augmentation procedures conducted by Periodontology residents, systemic and social factors were not evaluated, small patient pool, non-homogenous CBCT analysis across various software, lack of documentation regarding the location of perforation, and incongruence amongst studies in calculating metrics such as membrane thickness on CBCT. Future studies are recommended to control for these limitations and should further investigate possible confounders in their results. / Oral Biology

Introduction: The literature has suggested that minimal keratinized mucosa width (KMW) around osseointegrated implants, less than 2mm, may lead to a higher incidence of peri-mucositis, inflammation around the implant, and in the longer-term lead to peri-implant disease (Moraschini et al., 2017). Therefore, procedures to augment keratinized tissue have become a standard in periodontal plastic surgery, aiming to prevent peri-mucositis and peri-implantitis. Since the late 1960s, clinicians have corrected a lack of keratinized tissue by transplanting autogenous free gingival grafts (FGGs), and connective tissue grafts (CTGs) (Nevins et al., 2011) from the patient’s palate. Possible alternatives to FGGs and CTGs are xenografts and allografts (Dragan et al., 2017). Clinical studies have demonstrated a xenogeneic collagen matrix (XCM) potential as a means of increasing the width of keratinized tissue around dental implants without the need for an autologous graft and second surgical site (Rokn et al., 2020), improving patient post-surgical experience and increasing the willingness of patients to opt for further treatment. Purpose: This systematic review aimed to determine the clinical efficacy of using a xenogeneic collagen matrix (XCM) to augment keratinized mucosa width (KMW) around implants as a comparative alternative to free gingival grafts (FGG). Materials and Methods: Articles that were published between 1990 to November 2022 were electronically searched in six databases and manually searched in major periodontology and oral implantology journals and grey literature. The eligibility criteria comprised of randomized controlled trials (RCTs) and non-randomized clinical studies that analyzed the clinical efficacy of XCM for augmenting KMW around dental implants in comparison to FGG. Six studies were identified for final inclusion in this review and were included in the meta-analysis. The continuous outcomes were expressed as standardized means for KMW and PDs with a confidence interval (CI) of 95%. Outcome measures were statistically evaluated at the subject level. A fixed-effects model was used to pool the results from more than one study. Results: Six studies published between 2016 and 2021 were included in this systematic review and meta-analysis. Results from all six included studies were homogenous in concluding that FGG provided a greater overall increase in mean gain of KMW when compared to XCM; three of the six studies found this difference to be statistically significant. However, XCM still produced an average increase in KMW (2.84mm) that was significant from baseline, and comparable to FGG gains (4.07mm) at 6 months. Other clinical parameters such as PDs, BOP and/or GI were found to be statistically and clinically comparable between the test and control groups, suggesting both materials can provide peri-implant stability and health. Four of the studies provided data on patient-reported outcome measures. All four studies noted that the use of FGG graft was perceived as more painful at 2 weeks follow-up compared to XCM, which were also found to be statistically significant. One study mentioned that there was also a statistically significant difference in willingness for retreatment in the XCM group (76%) compared to the FGG group (43%). Two studies observed tissue shrinkage from baseline and determined that after 6 months there appeared to be significantly more tissue shrinkage with the XCM group compared to FGG. Another study that observed shrinkage over 5 years found a statistically significant difference between XCM and FGG, with the test group showing increasingly more shrinkage over long-term healing. Conclusions: The use of XCM around integrated dental implants improved KMW and provided stable and periodontally healthy probing depths, GI, and BOP indices with rates comparable to those for FGG. This review revealed that FGG could result in an overall greater increase in KMW than XCM. However, both XCM and FGG have demonstrated an increase in KMW ≥2mm around dental implants and maintain peri-implant health. A limited number of randomized controlled trials have compared the performance of xenogeneic collagen matrices with free gingival grafts around dental implants at longer healing periods and are needed to determine the true long-term efficacy of XCM as a substitute. / Oral Biology

Introduction: There is a growing body of literature investigating the detrimental effects of titanium and metallic particles in the peri-implant tissues. Metallic particles may be dispersed into the peri-implant tissues during implant placement, micro-mechanical wear, after implant debridement, or through corrosive electrochemical interactions with the adjacent microbiome. Dissolution of these particles into the peri-implant tissue may be an important pathogenic agent in the development of peri-implantitis. Our preliminary study showed that type of implant surface treatment influenced the quantity of particles released after titanium implant decontamination treatment using laser therapy in vitro. To the best of our knowledge, there are no studies evaluating the particle release from ceramic implants after laser irradiation. Purpose: The aim of this study is to investigate the particle release and potential induction of cytotoxicity and inflammatory response after implant decontamination of titanium and ceramic dental implants using laser therapy with an Er:YAG (erbium-doped yttrium aluminum garnet) laser. Materials and Methods: Three yttrium oxide stabilized tetragonal zirconium dioxide dental implants, three Titanium Alloy (Ti-6Al-4V ELI) dental implants with Laser-Lok® and resorbable blast texturing, and three (n = 3) Titanium Alloy (Ti-6Al-4V ELI) non-surface treated dental implants were irradiated using an erbium-doped yttrium aluminum garnet laser (Er:YAG) laser utilizing implant decontamination setting of 100 mJ, 2 W, and 20 Hz. Implants were sonicated in 1 mL of 70% denatured ethyl alcohol for 10 minutes, and 1 mL of supernatant was evaporated for 24 hours to retrieve metallic debris. Wells containing particles were cultured with human adult primary gingival fibroblasts and incubated at 37°C with 5% CO2. Scanning electron microscopy in a high-vacuum acceleration voltage with energy-dispersive X-ray was used to evaluate the morphology and elemental composition of the collected particles and dental implant samples. A firefly luciferase assay was used to determine the cell viability 48 hours, 72 hours, and 96 hours after initial seeding and incubation of the cells. A quantitative sandwich enzyme immunoassay technique was utilized to measure human IL-6 and TNF-α in the cell culture supernatants after 24 hours of incubation. Results: Titanium and zirconia particles were identified in the first two implant groups after laser irradiation. No particles containing elemental titanium were identified in the non-surface treated group. While inflammatory cytokines were detected in sufficient quantities representative of an inflammatory response, no comparison between groups was able to be made due to a lack of statistical power. Positive trends were measured in luminescence and absolute cell count over the four day experimental period in comparison to the medium containing control groups. Conclusions: Within the limitations of this study, ER:YAG laser irradiation generated titanium and zirconia particles from the titanium and zirconia test groups, but due to study design limitations, we are unable to conclude whether the metallic particles induced cytotoxicity or a proinflammatory response of human gingival fibroblast cells. / Biomedical Sciences