Decontamination of tried-in orthodontic molar bands

Molar bands are commonly used to retain orthodontic attachments on posterior teeth and due to the variation in the size of such teeth, it is usually necessary to 'try in' several bands before the correct one is selected. A possible concern with re-using such bands is the lack of cross-infection control, even following autoclaving, due to the presence of one or more small bore lumen (the archwire and headgear tubes). The aim of this experiment was, therefore, to determine whether such bands could be successfully decontaminated so that they could be re-used without a cross-infection risk. Two hundred orthodontic molar bands that had previously been tried in patients' mouths, but not cemented into place, were tested. Each band was decontaminated using an enzymatic cleaner/disinfectant and then sterilized using either a downward displacement (n = 100) or a vacuum cycle autoclave (n = 100). Following autoclaving each band was inoculated into brain heart infusion culture broth and incubated at 37 degrees C for 5 days. None of the decontaminated bands exhibited growth after 5 days. It would appear that, using this methodology, there is little risk of a cross-infection hazard occurring with the re-use of previously tried-in and decontaminated molar bands.     

Biocompatibility of resin-based materials used as pulp-capping agents

AIM: To evaluate and compare the response of pulps of rats capped with resin-modified glass-ionomer cement (RMGIC) or self-etching adhesive system. METHODOLOGY: Class I cavities were prepared on the occlusal surface of 54 maxillary first molars of 27 rats. Pulp exposure was performed on the cavity floor. The following resin-based materials were applied as pulp-capping agents: G1, Clearfil Liner Bond 2V (CLB 2V; Kuraray Co., Japan); G2, Vitrebond (VIT; 3M/ESPE, USA). In group 3 (control group), a calcium hydroxide/saline paste (CH; Labsynth, Brazil) was used. The cavities were restored with amalgam. After 7, 30 and 60 days, the animals were sacrificed and the jaws were processed for microscopic evaluation. RESULTS: Despite the inflammatory response caused by the experimental and the control materials at 7 days, pulpal healing associated with calcified barrier formation was observed at 60 days following the pulp therapy. Both resin-based materials promoted a large zone of cell-rich fibrodentine matrix deposition on the pulp horn related to the pulp exposure site, which was larger to VIT than to CLB 2V specimens. Tertiary dentine underneath the fibrodentine matrix was deposited by a layer of elongated pulpal cells. The remaining pulpal tissue exhibited normal histological characteristics. In the control group, healing and dentine-bridge formation was observed at 30 days. Pulpal breakdown occurred only when bacterial infection occurred. CONCLUSION: Both experimental pulp-capping agents allowed pulpal healing characterized by cell-rich fibrodentine and tertiary dentine deposition as well as calcified barrier formation.     

Serum mepivacaine concentrations after intraoral injection in young children

The authors measured plasma concentrations of mepivacaine in 36 children from the ages of 2 to 5 years who received dental care under light general anesthesia. The subjects were randomly assigned to receive either 2 percent mepivacaine hydrochloride with 1:20,000 levonordefrin or 3 percent mepivacaine hydrochloride without vasoconstrictor. The volume of anesthetic injected depended on the planned procedures for each patient. Blood samples (3 mL) were drawn from an intravenous line before and 5, 10, 20, 30, 45, and 60 minutes after mepivacaine injection. The serum was collected and analyzed by gas-liquid chromatography. Mean serum concentrations, normalized to a dose of 1 mg/kg body weight, reached a peak of 0.67 +/- 0.42 microgram/mL (mean +/- SD) after 3 percent mepivacaine and 0.63 +/- 0.21 microgram/mL after 2 percent mepivacaine with levonordefrin. Levonordefrin had no significant effect on the plasma concentrations. However, because of the higher concentration of mepivacaine in the 3 percent formulation, it was potentially 1.5 times as toxic (P < 0.002) on a volume basis. Statistical analysis also suggested that the maximum recommended dose of 3 mg/lb could result in potentially toxic blood concentrations in a small percentage of pediatric patients. The authors conclude that 3 percent mepivacaine should not be used when relatively large volumes of local anesthetic must be administered to small children and recommend that the maximum dose of mepivacaine not exceed 5 mg/kg.     

Testing the efficacy of 2 prototype brush heads for a powered toothbrush: refining the model

OBJECTIVES: To compare 2 prototype powered toothbrush (PTB) heads (A, B) to a marketed head (Sensiflex 2000) for plaque removing efficacy on the Philips/Jordan HX2550 PTB. MATERIALS AND METHODS: A 2-week, 3-group, single-blind trial recruited 78 volunteers (18-25). Plaque indices (PIs) were recorded at screening and 14 days later at baseline. Subjects were stratified (gender and PI) and then asked to abstain from oral hygiene measures for 48 h. A supervised episode of brushing with the allocated PTB head followed. Subjects then used the PTBs at home for the next 12 days before being asked to abstain from all oral hygiene measures for another 48 h prior to a second supervised brushing episode. Plaque was scored using a new modification of the Quigley & Hein Index (PI) at full mouth (FM), interproximal (IP) and smooth surfaces (SS). PIs were recorded before and after the supervised brushing episodes to enable the means of the within subject differences (pre- to post-brushing) to be compared between groups (ANOVA/t-tests). RESULTS: There were no significant differences in PI between groups at baseline or prior to the supervised brushings (p>0.05). Highly significant, mean reductions in PIs (approximately 1/2 of one PI unit) were observed for design B compared with the Sensiflex 2000 at FM and IP sites (p<0.0001) for both supervised brushing episodes. A significant reduction in PI at SS was seen only after the first brushing episode (p=0.0004). For design A, PI reductions were consistently greater than those for the Sensiflex 2000 but differences were only significant at the p<0.05 level. CONCLUSION: It is concluded that this model of clinical trial has sufficient power to demonstrate clinical superiority with respect to plaque removal for PTBs and can be used for testing one or more prototype designs of brush heads.     

Prevalence and trends in enamel fluorosis in the United States from the 1930s to the 1980s

BACKGROUND: The National Survey of Dental Caries in U.S. School Children: 1986-1987 conducted by the National Institute of Dental Research, or NIDR, remains the only source of national data about the prevalence of enamel fluorosis. The authors analyze these data and describe changes in the prevalence of enamel fluorosis since the 1930s, as reported by H. Trendley Dean. METHODS: A sample of children comparable to those described in the 1930s was selected from the NIDR data set among children living in households served by public water systems during the child's first eight years of life. The type of water system (that is, natural, optimal and suboptimal) for each household had been recorded in the NIDR data set using data from the 1985 U.S. Fluoridation Census. The NIDR data set included information about the children's history of fluoride exposure obtained from parents. RESULTS: In the 1986-1987 period, the prevalence of enamel fluorosis (ranging from very mild to severe) was 37.8 percent among children living in residences with natural fluoride (0.7 to 4.0 parts per million fluoride ions, or F-), 25.8 percent in the optimal fluoride group (0.7 to 1.2 ppm F- and 15.5 percent in the suboptimal fluoride group (< 0.7 ppm F-). The largest increase in fluorosis prevalence from the 1930s to the 1980s was in the suboptimal fluoride group (6.5 to 15.5 percent). CONCLUSIONS AND CLINICAL IMPLICATIONS: Exposure to multiple sources of fluoride may explain the increase in enamel fluorosis from the 1930s to the 1980s. The exposure to fluoride from sources such as dietary supplements has decreased since the 1980s because of reductions in the recommended dosage, but these changes occurred too late to have an effect on the study cohort. Evidence of simultaneous use of systemic fluorides indicates the need to reinforce guidelines for the appropriate use of fluorides and promote research on measuring total fluoride exposure.     

Local application of n-3 or n-6 polyunsaturated fatty acids in the treatment of human experimental gingivitis

BACKGROUND: Polyunsaturated fatty acids have the potential to attenuate inflammation by the synthesis of mediators of the 15-lipoxygenase pathways, which show opposite effects to the pro-inflammatory arachidonic acid metabolites such as leukotriene B4 (LTB4). AIMS: The aim of this clinical study was to evaluate the effects of topical application of n-6 or n-6 polyunsaturated fatty acids in patients with experimental gingivitis. METHODS: In each subject, similar teeth served as experimental and control over a 21-day non-hygiene phase and a 9-day resolving phase. Efficacy assessment was based on the bleeding on probing frequency (BOP) and the gingivocrevicular fluid volume (GCF). GCF was determined by inserting a filter paper strip for 30 s and measurements were performed on a Periotron 8000. The LTB4 concentration was analyzed by reversed-phase high-pressure liquid chromatography. RESULTS: After 21 days of plaque growth, the BOP, GCF and LTB4 levels were significantly increased in all groups, with no differences between the control and experimental side. Rinsing of an area with established gingivitis for a 9-day period significantly reduced the GCF in the n-6 group (71.9 (18.7) versus 47.4 (11.4) Periotron Units, median (inter quartile range)). CONCLUSION: The topical application of n-6 or n-6 fatty acids failed to inhibit the development of experimental gingivitis. Rinsing with n-6 fatty acids could reduce the level of GCF in established experimental gingivitis.     

Biomechanical response of bovine temporomandibular joint disc to prolonged tensile stress

This study was designed to evaluate the influence of prolonged tensile stress on the viscoelasticity of the temporomandibular joint (TMJ) disc. Twenty discs from 10, 3-year-old cattle were used. Tensile stress of 1.5 MPa was applied to specimens from the discs for 10, 20, 40 and 60 min. Following the prescribed period of tension for creep, the specimens were removed from the tension device and any recovery observed for 20 min. In all specimens, strain increased at the onset of stress application and reached almost steady conditions after 5 min. Although, the strain became slightly larger when the creep time was longer, no significant differences were found in the strains between any two tests with different periods of creep. The residual strain increased significantly with creep duration, and similarly the degree of recovery decreased significantly. In 10- and 20-min creep tests, the residual strains were 0.1 and 1.0%, the specimens in 40- and 60-min tests revealed irreversible changes in length. It was concluded that continuous loading for >40 min causes creep damage in bovine TMJ disc, and that prolonged sustained tension affects the recovery of joint homeostasis.     

Reducing patients' state anxiety in general dental practice: a randomized controlled trial

Anxiety assessment by questionnaire provides information for the dentist and may also confer a psychological benefit on patients. This study tested the hypothesis that informing dentists about patients' dental anxiety prior to commencement of treatment reduces patients' state anxiety. A randomized controlled trial was conducted involving eight General Dental Practitioners in North Wales. Participants included patients attending their first session of dental treatment, and accumulating a score of 19 or above, or scoring 5 on any one question, of the Modified Dental Anxiety Scale (MDAS). Patients (n = 119) completed Spielberger's state anxiety inventory (STAI-S) pre- and post-treatment and were randomly allocated to intervention (dentist informed of MDAS score) and control (dentist not informed) groups. Intervention patients showed greater reduction in mean change STAI-S scores (F[1,119] = 8.74, P < 0.0001). Providing the dentist with information of the high level of a patient's dental anxiety prior to treatment, and involving the patient in this, reduced the patient's state anxiety.