Color stability and hardness in dental composites after accelerated aging.

OBJECTIVES: To investigate the color and microhardness changes of five chemically- and five light-curing composites as a function of accelerated aging from light exposure. MATERIALS AND METHODS: From each material five composite specimens were embedded in epoxy resin prior to determining the Knoop microhardness of the surface. For analyzing the color DeltaE*=f((L*a*b*)) with a spectrophotometer, three discs per composite were prepared. After measuring the baseline for hardness and color the same specimens were exposed to a xenon arc light and water in a Weather-Ometer machine for a total radiant energy of 150 kJ/m2 and 122 h. The microhardness and the color were again determined following the aging treatment. RESULTS: Each material showed a significant increase in hardness after aging treatment (p<0.05). Comparing the hardness changes (in %) of the light-cured materials with the chemically cured materials, no significant difference could be found. Perceptible color differences could be observed for all the materials. Three brands showed small differences with DeltaE*=1.6-2.2, while four composites had DeltaE* ranging from 6.2 to 15.5. A significant correlation between hardness values and color changes could not be established. CLINICAL SIGNIFICANCE: The findings suggest that, since light-curable materials showed significantly more resistance to color changes after accelerated aging by light and water than chemically-cured materials, they may be more esthetically acceptable. Color changes were not correlated with surface hardness changes of the materials after aging.     

Patient perceptions of professionalism in dentistry

The purpose of this study was to examine how patients perceived the professionalism of University of Minnesota School of Dentistry students, faculty, and staff. Professionalism is defined by the authors as an image that will promote a successful relationship with the patient. Patients within comprehensive care clinics were asked to assess physical attributes and behaviors of the dental care providers using a questionnaire. The patients read statements dealing with characteristics of the dental care providers and responded as to whether they agreed, were neutral, or disagreed with the statement. The surveyed population consisted of 103 males and 97 females, 64 percent of whom lacked insurance coverage. Fifty-one percent of the patients were between the ages of forty-four and sixty-nine, but the overall age distribution was dispersed over a range of eighteen to one hundred. Our research found that all dental care providers displayed a professional appearance as well as behavior. The attire of the dental care provider affected the comfort and anxiety levels of patients, as did first impressions of both students and faculty. Most patients reported that students and faculty displayed effective time management and used appropriate language during the appointment. Finally, hairstyle, makeup, and jewelry appeared to have little effect on patients' opinions of the various dental care providers.     

Pain experienced by patients during periodontal maintenance

BACKGROUND: The aims of this study were to determine: 1) the degree of pain experienced by patients during probing and debridement; 2) whether the treating hygienists could estimate the degree of pain experienced by the patients; and 3) whether the patients' pain responses could be predicted by factors such as the patients' age, gender, number of residual periodontal lesions, and answers to a questionnaire on dental anxiety. METHODS: Prior to periodontal maintenance procedures, two groups of 20 adult patients to be treated by two hygienists completed an anxiety questionnaire. Subsequently, measurements of probing depths were performed, followed by pain ratings by each patient using a visual analog scale (VAS). The hygienists also completed a VAS, estimating the pain level they perceived their patient to have experienced. The same protocol was repeated for instrumentation (debridement). RESULTS: Most patients showed low pain responses to both probing and instrumentation. However, using an arbitrary threshold of VAS > or = 40 mm, 20% to 33% of the patients had a significant pain experience. The hygienists were quite accurate in their relative estimates of their patients' pain experiences. Regression analyses disclosed that significant portions of the pain responses could be predicted by the patients' answers to one of the dental anxiety questions. CONCLUSIONS: Recognition of patients who are likely to experience significant pain during periodontal treatment may be facilitated by the use of one question on dental anxiety. During treatment, the ability to gauge and respond to patients' pain experiences would seem to be an important component of a therapist's clinical skills.     

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.     

Lasers in dentistry. Epilogue

Laser use in the dental clinic requires scientifically demonstrated improvement for patient and/or dentist, easily obtainable equipment, adequate training and safety. These aspects are summarized for all laser applications. Improvement has not been shown for all applications. In the Netherlands manufacturer-independent training is little available. Safety requires care, but not a large investment. Economical aspects include an adequate compensation for the necessary investment. For only a few applications laser treatment leads to decreased cost or time of treatment. However, also increased compensation by insurers or patients may be possible; some patients will be willing to pay more when laser treatment is less unpleasant than traditional treatment or, in the case of diagnosis, leads to better information.