Comparison of failure loads and compressive stress in Press on metal and Press on Y-TZP copings.

OBJECTIVE: The aim of the study was to assess the failure loads and compressive stresses among bilayered press on Y-TZP (POZ) and press on metal (POM) crowns with different core-veneer thickness. METHODS: Thirty metal and Y-TZP copings were fabricated using CAD-CAM technology with specified thickness. All copings were veneered with ceramic materials using hot pressing technique, with 2mm and 2.5mm thickness. The different coping veneer thickness of crowns resulted in six study groups, including, POM: Coping/ veneer thickness of 0.7/2mm (Gp1), 0.7/2.5mm (Gp 2) and 1mm/2mm (Gp 3)-POZ: 0.7/2mm (Gp A), 0.7/2.5mm (Gp B) and 1mm/2mm (Gp C). Crowns were cemented to a standard implant analog and failure loads (FL) and compressive stress (CS) was ascertained by controlled load application in a universal testing machine. Data was analysed using ANOVA and multiple comparisons test. RESULTS: The maximum FL were observed in the POM specimens with a C/V ratio of 1/2 (Group 3-1880.67± 256.78 N), however the lowest FL were exhibited by POZ crowns with 1/2 C/V ratio (Group C-611.89± 72.79 N). Mean FL and CS were significantly higher in POM compared to POZ crowns in respective groups. Increasing the coping-veneer thickness increased FL and CS among POM crowns. Increasing veneer and decreasing coping thickness improved FL and CS among POZ crowns. CONCLUSIONS: Press on metal specimen showed higher resistance to fracture than Press on Y-TZP specimens. Improved failure loads were observed in thin coping and thick veneers among Press on Y-TZP crowns.

Influence of Bioactive, Resin and Glass Ionomer luting cements on the fracture loads of dentin bonded ceramic crowns.

OBJECTIVE: To investigate the failure loads of dentin bonded all-ceramic crowns when luted with Bioactive, resin and glass ionomer cements (GIC) in an in-vitro setting. METHODS: This study was conducted at King Saud University, Saudi Arabia, from Nov.2018 to March 2019. In this study, 60 premolar teeth were prepared for dentin-bonded ceramic crowns. Lithium disilicate ceramic crowns fabricated using CAD-CAM technique were cemented to teeth using Bioactive (ACITVA), Resin (Nexus 3 Gen) and GIC (Ketac Cem- Maxicap). Half of the bonded specimens in each group were thermocycled (50000 cycles), however the remaining half were not aged (n=10). Fracture loads of bonded crowns were assessed by exposing them to static axial occlusal loads (1mm/min) using a round ended metal probe in a Universal testing machine. Means and standard deviations among the study groups were compared with ANOVA and Tukey-Kramer multiple comparisons test. RESULTS: Highest failure loads were observed in resin group without ageing (thermocycling) (689.13±89.41 N), however, the lowest loads were observed in GIC specimens with ageing (243.16±49.03 N). Among non-aged samples, failure loads for Bioactive (480.30±47.26 N) group were less than Resin (689.13±89.41 N) samples but higher than GIC (307.51±45.29 N) specimens respectively. Among the aged specimens, Bioactive (404.42±60.43 N) showed significantly higher failure loads than GIC (243.16±49.03 N), however lower failure loads than Resin (582.33±95.95 N) samples. CONCLUSIONS: Dentin boned crowns with resin cementation showed higher failure loads than Bioactive and GIC luted crowns. Crowns luted with Bioactive cement showed acceptable failure loads for use as restoration on anterior teeth.

Assessment of factors influencing oral health-related quality of life (OHRQoL) of patients with removable dental prosthesis.

OBJECTIVE: The aim of this study was to evaluate factors affecting oral health related quality of life (OHRQoL) of patients using removable dental prosthesis. METHODS: The present study employed a cross sectional analytical design. A total of 200 patients participated and interviewed using a cross sectional analytical design. In the first section of the questionnaire patients were asked about demographic data whereas the second part of the questionnaire assessed medical history, oral habits, smoking status, oral hygiene habits and frequency of dental visit. The questionnaire also collected information regarding patient's removable prosthesis. Questionnaire of OHIP-DENT (Oral Health Impact Profile) was also employed to measure oral health quality of life (OHRQoL) on the domains of functional limitation (FL), physical pain (P1), psychological discomfort (P2), physical disability (D1), psychological disability (D2), social disability (D3) and handicap (H). Relationships between the demographic, socio-economic and education variables and others OHIP-EDENT scores were explored by comparing mean scores by applying ANOVA. RESULTS: The study participants comprised of 107 males (53.5%) and 93 females (46.5%). Regarding oral care, participants reporting to visit their dentist within one year were 40.0%. The highest score was recorded for the functional limitation (FL) domain (15.62±6.6), followed by social disability (D3) (15.23±5.06) and physical pain (P1) (14.28±4.8). The respective scores for physical (D1) and psychological disability (D2) and handicap (H) were 10.47±4.84, 11.32±5.38 and 12.45±4.50 respectively. CONCLUSIONS: Removable partial denture patients showed minimum problems with mastication, social compromise and functional discomfort. The oral health quality of life of removable denture patients is significantly influenced by patient education level, socio-economic status, medical conditions, smoking and tobacco use habits.

Clinical and microbiological outcomes of photodynamic and systemic antimicrobial therapy in smokers with peri-implant inflammation.

AIM: To compare the effectiveness of two protocols in the treatment of peri-implant mucositis (p-iM) among cigarette smokers. MATERIALS AND METHODS: Three groups were randomized into (i) single session of antimicrobial photodynamic therapy (aPDT) with mechanical debridement (MD) (Group-A), (ii) systemic AB with MD (Group-B), and (iii) MD alone (Group-C). Clinical peri-implant parameters including plaque scores (PS), bleeding on probing (BOP) and probing depth (PD) were measured at baseline, 6 weeks and 12 weeks. Microbiological parameters included the assessment of percentage level of Pseudomonas aeruginosa and Staphylococcus aureus at baseline and 12 weeks. All parameters were analyzed using Friedman test and multiple comparisons performed using Bonferroni tests. P-value less than 0.05 were considered statistically significant. RESULTS: At 6 weeks of follow-up, there was a statistically significant reduction in PS (p < 0.001), BOP (p < 0.01), and PD (p < 0.05) among patients in groups A and B on intragroup comparison. At 12 weeks of follow-up, there was a further significant reduction in PS (p < 0.001) and BOP (p < 0.01) among patients in groups A and B on intragroup comparison but this reduction was comparable with 6-week follow-up. On inter-group comparison, only Group-A showed statistically significant reduction in BOP compared to Group-B and C at 6 weeks (p < 0.05). The levels of both P. aeruginosa and S. aureus in Group-A and Group-B showed statistically significant reductions at 12 weeks compared with baseline (p < 0.01). On inter-group comparison, Group-A and B showed no significant differences at follow-up (p > 0.05). CONCLUSION: This short term clinical study suggests that aPDT as an adjunct to MD is as efficacious as adjunctive antibiotic therapy. However, additional benefits in the reduction of bleeding scores were observed for aPDT in peri-implant inflammation among cigarette smokers.