Effect of repeated heating and cooling cycles on the degree of conversion and microhardness of four resin composites.

OBJECTIVE: This study evaluated the effect of repeatedly heating and cooling four resin-based composites (RBCs) for up to six cycles. MATERIALS AND METHODS: Four commercial RBCs were heated to 68°C and cooled to room temperature for up to six cycles before photocuring at 30°C. Specimens spent a total of 0, 30, 60, 90, 120, 150 min, or 7 days at 68°C. The degree of conversion (DC) was measured at the bottom of the specimens immediately after photocuring. The Vickers microhardness was measured at the top and bottom of the RBC surfaces 24 h after photocuring. The data were analyzed using one-way analysis of variance, Dunnett's or Bonferroni post-hoc tests, and Spearman correlation analysis (α = 0.05). RESULTS: For two brands of RBC, the DC decreased at various time points; however, these decreases were small, and there was no correlation (negative or positive) between the number of heating cycles and the DC for any of the RBCs. Repeated heated and cooling resulted in small changes in the hardness (compared to the control) in both directions (Dunnett; p < 0.05). Two of the RBCs showed a significant, positive correlation between the number of heating cycles and their hardness at the bottom surface. CONCLUSION: Repeated heating, cooling, and then reheating the RBCs for up to 1 week had little overall effect on their DC and microhardness values. The 2 mm thick specimens of all four RBCs achieved a bottom: top hardness ratio exceeding 0.8 after a 20 s exposure to light from a commercial LED curing light CLINICAL SIGNIFICANCE: Six repeated dry heating and cooling cycles of up to 1 week in duration had little effect on the DC and the microhardness of four commercial resin-based composites.

Knowledge Translation Among General Dental Practitioners in the Field of Periodontics.

INTRODUCTION: Evidence-based practice (EBP) is an expectation of medical professionals and is positively received in the dental community. Investigations of evidence-based dentistry (EBD) have discussed its use in broad terms and daily clinical practice, but there is only limited information about its use and barriers with respect to particular dental specialities. METHODS: A cross-sectional questionnaire was developed to survey implementation and obstacles to EBP; EBD specific to periodontics; and preferences for types of dissemination of evidence. The target population was active general dentists in Nova Scotia (n = 446). An email link to the questionnaire was distributed to dentists, and reminders were sent 4 and 10 days later. RESULTS: The response rate was limited (16.6%). Most respondents were comfortable evaluating the growing body of research, although many reported use of low-level evidence, including that from other health professionals or expert opinion. A common barrier to use was insufficient time. Respondents who found strong evidence for certain periodontal procedures were more likely to refer these procedures, which included tissue regeneration and periodontics related to endodontics. On-site lecture-based dissemination was preferred by most respondents. CONCLUSION: General evidence-based concepts and use were similar to EBD results reported elsewhere, although external validity is limited by our low response rate and narrow target population. Specific data related to periodontics may be useful in directing a modified questionnaire to a broader target population. Respondents who are truly interested in EBD and responded to our questionnaire may ultimately benefit the most from our results, where further educational opportunities can be tailored to overcome the identified barriers and aid in more effective translation of evidence-based periodontal decisions in a general dental practice.

Reversing the effects of 2% Lidocaine: A randomized controlled clinical trial.

OBJECTIVES: Prolonged soft tissue anesthesia following a dental appointment is a complaint that is frequently reported by patients. Soft tissue anesthesia generally exceeds the duration of pulpal anesthesia by a few hours. This can lead to difficulties with smiling, drinking, speaking and lip/cheek biting following dental appointments. Phentolamine Mesylate (PM) is a pharmacological agent capable of reducing the duration of soft tissue anesthesia following dental treatments. Many clinical trials supporting its efficacy have used sham injections compared to injections with PM. The present study aims to evaluate the effect of PM on the duration of soft tissue anesthesia compared to a control injection of saline water. METHODS: This randomized controlled trial recruited 40 participants above 18 years of age. Following an inferior alveolar nerve block using 1.8 ml of Lidocaine 2%, 1:100 000 epinephrine, participants were randomized into one of 2 groups. The test group received an injection of 0.4 mg PM (OraVerse). Participants in the control group received an injection of sterile saline water. Participants were trained in self-assessing their anesthesia, which they did until return to normal sensation. RESULTS: Thirty-six participants completed the study. PM significantly reduced the duration of soft tissue anesthesia in the lower lip (104 vs 170 min, p = .001), and tongue (83 vs 134 min, p = .004) compared to the control injection. No serious adverse events were encountered. The only adverse events observed were post-operative pain and discomfort. CONCLUSIONS: Phentolamine Mesylate hastens the return to normal soft tissue sensation and function by approximately one hour compared to a control injection of water. CLINICAL SIGNIFICANCE: Phentolamine Mesylate can be considered a safe and effective way of reducing the duration of soft tissue anesthesia following a dental appointment. This controlled clinical trial is registered at the National Institutes of Health (ClinicalTrials.gov) #NCT02861378.

The oral health status of recent immigrants and refugees in Nova Scotia, Canada.

There are no published reports on the oral health status of adult immigrants and refugees in Canada. An oral health interview and clinical oral examination were conducted on 45 recent immigrants and 41 recent Bhutanese refugees, aged 18-67, in Nova Scotia, Canada. Over half (53%) of the immigrants and 85% of the refugees had untreated decay. Most (89% of immigrants; 98% of refugees) had moderate to severe gingivitis and the majority (73% of immigrants; 85% of refugees) had moderate to severe periodontitis. Despite these, 64% of immigrants and 49% of refugees rated their oral health as good, very good or excellent, and most believed they did not need fillings or periodontal treatment. Oral disease among the study sample was higher than the Canadian average and there was a striking discrepancy between self-reported and clinically determined need for dental care.