Effect of thixotropic agents as additives on the mechanical properties of maxillofacial silicone elastomers.

STATEMENT OF PROBLEM: The incorporation of thixotropic agents to prevent slumping during the silicone packing procedure may alter some favorable mechanical properties of the silicone elastomers and could possibly influence the success of the prosthesis. PURPOSE: The purpose of this in vitro study was to evaluate the effect of adding thixotropic agents on the mechanical properties of 3 commonly used silicone elastomers. MATERIAL AND METHODS: Specimens of 3 maxillofacial silicones (M511, Z004; Technovent Ltd, and A2000; Factor II Inc) were prepared according to the manufacturers' instructions. Tear and tensile strength values and percentages of elongation and hardness were evaluated for each material with and without thixotropic agents. Data were analyzed using 1-way ANOVA and the Bonferroni post hoc test (α=.05). RESULTS: Results showed that the 3 types of silicone elastomers had significantly different (P<.001) tensile and tear strength and hardness values and percentages of elongation. Z004 silicone showed the highest tensile and tear strength followed by A2000 and M511, regardless of the addition of thixotropic agent. The addition of a thixotropic agent decreased the tear strength (P<.001) but not the tensile strength for all types of silicone. Percentage of elongation was the highest in M511 and the lowest in A2000 and was significantly higher (P<.001) for silicones with no added thixotropic agent. Hardness was highest in A2000 and lowest in M511. Adding a thixotropic agent decreased hardness significantly (P<.001) for Z004 and A2000 only. CONCLUSIONS: The incorporation of thixotropic agents into the 3 maxillofacial silicone elastomers used in this study reduced some favorable mechanical properties, particularly tear strength and percentage of elongation. Z004 showed superior mechanical properties among the 3 tested silicones.

Prosthodontic Rehabilitation of Arabic Speaking Individuals with Velopharyngeal Incompetence: A Preliminary Study.

BACKGROUND: Hypernasality is a frequently encountered problem in the speech of individuals with velopharyngeal incompetence. The use of palatal lift appliance (PLA) is the main treatment option for correction of velopharyngeal incompetence. The literature on the outcomes of using prosthetics treatment for Arabic speaking patients is scarce. OBJECTIVE: The aim of this study was to investigate the effect of using PLA on hypernasality of Arabic speaking patients with velopharyngeal incompetence. METHODS: Six participants with age ranging from 9 to 61 years (4 males and 2 females) were recruited between October 2013 and August 2014. Written informed consents were taken from all the adult participants/the guardians of under-aged participants. All patients exhibited hypernasality with different etiologies for velopharyngeal incompetence (head injury, cerebrovascular accident, and neurological disorders). They were treated with PLAs which were constructed to elevate the dysfunctional soft palate. Nasalance scores and perceptual speech acceptability ratings were measured/evaluated in both situations; with and without appliances. Paired t-test was used to analyze the perceptual ratings and nasalance scores in order to detect any significant change in hypernasality pre and post insertion of PLA. RESULTS: There was a statistically significant decrease (p>0.05) in nasalance scores (Pa, Pi, Ma, Mi, a, i) after PLA insertion. The subtest /u/ showed insignificant change (p= 0.056). Perceptual ratings showed significant reduction in hypernasality which was consistent with nasalance measurements. CONCLUSION: PLAs can reduce hypernasality in Arabic speaking patients who suffer from velopharyngeal impairment.

The Effect of Waterpipe Smoking on Periodontal Health.

PURPOSE: To determine the effect of waterpipe smoking on periodontal health. MATERIALS AND METHODS: The study included 190 participants who were categorised into four groups; cigarette smokers, waterpipe smokers, dual smokers and nonsmokers. Intraoral examination included plaque (PI), gingival (GI) and calculus (CI) indices, probing pocket depth (PPD), clinical attachment level (CAL) and bleeding on probing (BOP). RESULTS: The four groups differed significantly in the prevalence and extent of periodontal disease. Pairwise comparison tests showed that the means of percentages of sites with PPD > 3 mm, PPD > 4 mm, CAL > 1 mm and bleeding on probing were significantly higher among smoking groups compared to the nonsmoking group (p < 0.05). After adjusting for age, cigarette smokers (OR = 4.6), waterpipe smokers (OR = 4.3) and dual smokers (OR = 4.9) were significantly more likely to have periodontal disease compared to nonsmokers. When data were analysed according to the smoking method, no significant differences in the odds of periodontal disease were detected between different smoking groups (p > 0.05). CONCLUSION: Waterpipe tobacco smoking is not an alternative, safe way of smoking considering periodontal disease. Thus, global actions against waterpipe smoking are required.