The safety and efficacy of treatment with air abrasion technology.

AIMS: To evaluate patient and operator exposure to respirable particulates following the use of air abrasion in tooth preparation, and to compare the microleakage of pit and fissure sealants after conventional, bur and air abrasion preparation of the pits and fissures. METHODS: To examine air abrasion safety, sampling data were collected using a physical model of the upper torso of a patient. Previously extracted bovine incisors were prepared using an air abrasion instrument. Patient and operator exposure samples were collected. The variables examined included the size of the alumina oxide particles, the speed of particle delivery and the method of dust collection. To assess the efficacy of air abrasion, 36 extracted human molars were divided into three groups. The groups were prepared by conventional acid etching, opening the pits and fissures with a round bur, or by air abrasion. To simulate oral conditions, sealed teeth were immersed in artificial saliva and thermocycled. Teeth were immersed in a 1% solution of methylene blue and sectioned to assess the microleakage associated with each sealant. CONCLUSIONS: (1) Dust from the KCP 1000 is insufficient to be a health hazard to patients or operators, (2) chair-side suction can be used as an alternative to the KCP 1000 suction, (3) superior sealants were obtained when tooth surfaces were prepared by a bur, compared to air abrasion and conventionally prepared surfaces, and (4) air abrasion tooth surfaces demonstrated less microleakage than conventionally prepared tooth surfaces.

Microleakage of sealants after conventional, bur, and air-abrasion preparation of pits and fissures.

PURPOSE: The aim of this study was to compare the microleakage of unfilled and filled sealants after conventional, bur, and air-abrasion tooth preparation. METHODS: Seventy-two extracted molars were randomly divided into three groups. In group 1, 24 teeth were prepared by pumicing and acid etching with 37% phosphoric acid. In group 2, 24 teeth were prepared with a 1/4-round bur in a low-speed handpiece and then acid etched. In group 3, 24 teeth were prepared by high-speed (160 PSI) microabrasion using 50 mu alpha alumina particles in a KCP 2000 machine. In each group, 12 teeth were sealed with a filled sealant and 12 teeth with an unfilled sealant. All the teeth were stored in artificial saliva for 7 days and thermocycled for 2000 cycles. Teeth were then sealed apically and coated with nail varnish 1 mm from the margins and stained in 1% methylene blue for 24 h. Each tooth was sectioned in three locations and ranked (0-3) for microleakage. RESULTS: There were 216 sections and 66% showed no leakage. CONCLUSIONS: Chi-square statistical analysis of the data led to the following conclusions: 1) superior results were obtained when the tooth surfaces were prepared by a bur, 2) conventionally and KCP 2000-prepared tooth surfaces yielded similar results, and 3) the unfilled sealant was superior to the filled sealant.

Bond strengths of two ceramic brackets using argon laser, light, and chemically cured resin systems.

The present study compared tooth-bracket bond strengths using two types of ceramic brackets and three methods of polymerization: argon laser, conventional light, and chemical. Ninety extracted human premolars were prepared for bonding with pumice and gel etchant. Using single crystal alumina brackets with silanated bases, three groups of 15 teeth were bonded with one of the three polymerization methods. Similarly, three groups of 15 teeth were bonded with polycrystal alumina brackets with nonsilanated bases. Each bonded bracket was tested on an Instron tensile testing machine in shear mode to determine shear debonding strength. Fracture sites were recorded. Results demonstrated that (1) all combinations produced shear bond strengths greater than those considered clinically acceptable, (2) the mean shear bond strengths of the single crystal alumina brackets with silanated bases were significantly higher than those of the polycrystal alumina brackets with nonsilanated bases, and (3) no enamel fractures were found on debonding the chemically cured brackets while the light and laser groups exhibited a 10% rate of enamel fracture on debonding.

The management of premolar supernumeraries in three orthodontic cases.

This paper reviews the incidence, etiology and location of supernumerary teeth with emphasis on premolar supernumeraries and examines the management of supernumerary premolars of three patients undergoing orthodontics. These cases demonstrate that the management of premolars is assessed individually and treatments based on potential complications, which may occur during the orthodontic and surgical management of the dentition. Progress and posttreatment radiographs are recommended for the assessment of late forming supernumerary teeth.

The effect of internal bevel on marginal leakage at the approximal surface of Class 2 composite restorations.

The aim of this study was to assess the effect of intentionally leaving undermined enamel (internal bevel) along the cervical margins of class 2 composites on marginal leakage. Conventional MO and DO cavity preparations were prepared in 25 extracted permanent premolars. In each tooth the cervical margin was a butt-joint for the control group and an internal bevel for the experimental group. A transparent celluloid matrix was adapted and the teeth were restored with scotchbond Multi-Purpose and increments of Z100. A U-shaped increment was attached to the buccal and lingual walls and cervical floor of the box, leaving a gap for a middle increment. A third increment filled the occlusal part of the cavity. Following thermocycling the teeth were immersed in basic fuchsin for 24 hours, and 0.5 mm-wide sections were cut in a mesiodistal direction. Dye penetration was scored: 0 = no penetration; 1 = dye along enamel tooth interface; 2 = dye along the gingival floor; 3 = dye along pulpal wall; 4 = dye penetration into dentinal tubules. The experimental group showed 17 teeth (68%) with no dye penetration, compared to eight (32%) in the control group. Severe dye penetration (score 4) was found in only four teeth (16%) of the experimental group and 12 (48%) of the controls. The difference between the groups was statistically significant (Wilcoxon matched-pairs signed-rank test; P < 0.01). This study showed that an internal bevel at the cervical margins of class 2 composite restorations reduces marginal leakage when compared to a conventional butt-joint cavity preparation.

Management of lower incisor crowding in the early mixed dentition.

This paper describes normal and problem development in lower incisor positioning and offers options for management of crowded cases. The following guidelines were recommended, (1) lower incisor crowding of 2 mm or less and with an intercanine width greater than 28mm will usually resolve spontaneously, (2) lower incisor crowding of 3-4 mm is best managed by discing of the primary dentition, (3) crowding assessment of 5-9 mm requires extraction of primary teeth with probable placement of a supportive lingual arch and, (4) crowding greater than 10 mm requires fixed appliance therapy and careful orthodontic management with attention to the severity of the malocclusion.

The effectiveness of infiltration anesthesia in the mandibular primary molar region.

The purposes of the present study were to determine the effectiveness of infiltration anesthesia in the mandibular primary molars, and how patient age, tooth location, and anesthetic type relate to the quality of anesthesia. Data were derived from 66 subjects, 42-72 months old, requiring restorative treatment in mandibular primary molars. Infiltration anesthesia was provided with mepivacaine hydrochloride 2%, prilocaine hydrochloride 4%, and articaine hydrochloride 4%. After 10 min, probing, rubber dam placement, and drilling were initiated. Procedures were videotaped and ratings of comfort and behaviors were made using the SEM scale and the Frankl Behavioral Scale. The conclusions were: 1) sixty-five per cent of the subjects experienced little or no pain; 2) children who demonstrated little or no pain during injection were likely to be comfortable during successive procedures; 3) there was a high relationship between children behaving cooperatively and comfort during procedures; and 4) the quality of anesthesia was not significantly related to tooth location, age, or type of anesthetic agent.

A survey of sealant use by Canadian dental practitioners.

Although there are reports on the use of fissure sealants in the United States, little information is available about the extent to which this preventive measure is used in Canada. This study reports the results of a survey of sealant use. Based upon the responses from 589 Canadian dental practitioners, it was found that 84.8% used sealants in their practices. There was no statistically significant difference in sealant use between dentists in fluoridated and non-fluoridated areas. However, usage increased with the number of dental auxiliaries in the practice. There also was more use of sealants in patients covered by dental insurance. Sealant usage declined the longer dentists had been in practice. Light-cured, tinted sealants appeared to be the most popular types.

A comparison of S. mutans clinical assessment methods.

The purpose of this investigation was to compare the tongue blade/Rodac plate assessment method, the Cariescreen (APO Diagnostics Inc., Toronto, Ontario, Canada) method, and a modified Cariescreen method for S. mutans assessment. Ninety-one triple tests were done on 23 children 1 to 4 years of age, and the S. mutans counts were compared. When all 91 tests were compared, there was agreement 86.3% of the time between the tongue blade/Rodac plate assessment method and the modified Cariescreen method. When the Cariescreen method was compared to the tongue blade/Rodac (Becton Dickins Labware, New Jersey) plate technique, there was agreement 72.2% of the time. Agreement tended to be at the low and high infection levels. When the Cariescreen and modified Cariescreen methods were compared with the tongue blade/Rodac method, most discrepancies were in the moderate range of S. mutans counts. Averages and standard deviations were 80.1 vs 32.1 for the modified Cariescreen method, and 86.9 vs 90.2 for the tongue blade/Rodac method. The linear product moment correlation coefficient was +.69. Overall, the modified Cariescreen method compared more favorably to the tongue blade/Rodac plate assessment than the Cariescreen method did.

Variables influencing Streptococcus mutans testing.

When saliva is sampled to estimate S. mutans, variables may influence the results. The purpose of the present study was to assess the reliability of the tongue depressor for saliva sampling, and whether the sampling time during the day influences S. mutans counts. The study population consisted of 27 children, between 24 and 66 months of age. Samples of unstimulated saliva were gathered on tongue blades four times during the day for each subject. Paired samples representing both sides of the tongue blades were inoculated onto elevated agar plates containing a selective medium, and anaerobically incubated at 37 degrees C for 48 hr. After examining 76 paired samples of saliva, no significant differences in S. mutans counts were found between sides of the spatula, suggesting that the sampling technique was suitable. Analysis of variance showed significant differences within each subject over the four sampling times (P less than .01). A significant difference was found between subjects' daily averages (P less than .05).

Use of articaine local anesthesia in children under 4 years of age--a retrospective report.

A retrospective survey reports the use of articaine hydrochloride as an anesthetic in children under 4 years of age. Data was collected by a record audit in two pediatric dentistry offices. Articaine anesthetic was administered to 211 patients, 29 having additional administrations of the agent. In some instances, the dosages exceeded the recommended concentrations for older children. No adverse systemic adverse reactions were noted on the charts or known to the clinicians. The present report provides initial evidence for the use of articaine in children under 4 years of age.

A comparison of two systems for measuring water fluoride ion level.

The purpose of this study was to assess the reliability of measurements of fluoride ion concentrations as determined by the Orion fluoride meter and electrodes (Orion models SA 720 meter, 94-09, 90-01-00, and SA 720 meter, Orion Research Incorporated, Laboratory Products Group, Boston, MA) and to reference electrodes with a digital meter and the Hach colorimeter (DR100 colorimeter, Hach Company, Loveland, CO). Three groups of drinking water samples were collected simultaneously from each of 53 elementary schools in Oxford County, Ontario, Canada. Samples in Groups 1 and 2 were analyzed for fluoride at the University of Western Ontario using the colorimetric method and the specific ion electrode system respectively. Samples in Group 3 were analyzed at the Ontario Ministry of the Environment laboratories; these results were used as the "gold standard." The overall results of the study suggest that with proper calibration the colorimeter system may be a valid, reliable, and affordable tool for fluoride analysis in the dental office.

Correlating Streptococcus mutans with dental caries in young children using a clinically applicable microbiological method.

The present study used a clinically applicable microbiological method to correlate Streptococcus mutans counts and dental caries prevalence in young children. The study population consisted of 37 subjects, between 16 and 60 months of age. Using a sterile tongue depressor, samples of unstimulated saliva were obtained from subjects and inoculated onto elevated agar plates containing a selective medium. Plates were incubated anaerobically at 37 degrees C for 48 h. chi 2 and multiple regression analyses gave highly significant relationships (p less than 0.01) between dental caries prevalence and the number of S. mutans colonies.

The unpredictability of primary molar resorption following ectopic eruption of permanent molars.

Two case reports are given, demonstrating what appears to be two types of resorption associated with ectopic eruption. In both cases a progressive resorptive process occurred on one side and a stationary type on the other. Close follow-up is important; it resulted in a successful outcome for the patient in case 2 here, whereas the first patient required major orthodontic treatment because of the ectopic eruption.