David W. Banting

Dental Flossing and Interproximal Caries: a Systematic Review

Our aim was to assess, systematically, the effect of flossing on interproximal caries risk. Six trials involving 808 subjects, ages 4 to 13 years, were identified. There were significant study-to-study differences and a moderate to large potential for bias. Professional flossing performed on school days for 1.7 years on predominantly primary teeth in children was associated with a 40% caries risk reduction (relative risk, 0.60; 95% confidence interval, 0.48–0.76; p-value, < 0.001). Both three-monthly professional flossing for 3 years (relative risk, 0.93; 95% confidence interval, 0.73–1.19; p-value, 0.32) and self-performed flossing in young adolescents for 2 years (relative risk, 1.01; 95% confidence interval, 0.85–1.20; p-value, 0.93) did not reduce caries risk. No flossing trials in adults or under unsupervised conditions could be identified. Professional flossing in children with low fluoride exposures is highly effective in reducing interproximal caries risk. These findings should be extrapolated to more typical floss-users with care, since self-flossing has failed to show an effect.

Streptococcus mutans and Lactobacillus Detection in the Assessment of Dental Root Surface Caries Risk

Forty-five subjects contributing 150 root surfaces with gingival recession were sampled seven times over a 32-month period. We calculated isolation frequencies of lactobacilli on selective Rogosa SL agar and S. mutans in a sensitive enrichment broth and on mitis salivarius agar. Both S. mutans and lactobacilli were isolated more frequently from surfaces which became carious than from those remaining caries-free. Isolation frequencies were also higher for caries-free surfaces in caries-active subjects than for caries-free surfaces in caries-inactive subjects. The presence or absence of S. mutans and lactobacilli in samples taken at baseline could discriminate between subjects who were to be root-caries-active and those who were to remain root-caries-inactive during the subsequent observation period. Moreover, if both bacteria were detected or only S. mutans was detected on a root surface at its entry into the study, that surface had a greater risk for developing a root lesion. However, the tests could not predict which root surfaces within the mouths of caries-active subjects were to become carious. Analysis of the data suggests that simple microbiological detection tests may be useful in identifying patients at high risk of root caries.

CLINICAL SCIENCE Longitudinal Microbiological Investigation of a Hospitalized Population of Older Adults with a High Root Surface Caries Risk

Intact root surfaces of chronically hospitalized subjects were sampled periodically to enumerate bacterial species believed to be associated with root caries. Bacteria were cultivated and enumerated using a series of selective and enriched media. Microbial counts, isolation frequencies, and percent cultivable flora data were analyzed for caries-active and caries-free surfaces and subjects. S. mutans, S. sanguis, A. viscosus, A. naeslundii, total lactobacilli, and Veillonella accounted for a mean of less than 20% of the cultivated flora, with mitis salivarius agar cultivable streptococci averaging less than 5%. The microbial count data were highly variable, precluding the finding of significant differences in caries association for either subjects or sites. Streptococci, especially S. mutans, correlated highly with lactobacilli in the samples.

Polymerization with the Argon Laser: Curing Time and Shear Bond Strength

The objective of this study was to determine the efficiency of an argon laser in polymerizing a light-cured orthodontic adhesive. Metal brackets were bonded to 185 premolars, divided into 5 different protocol groups of 37 each as follows: light 40-second buccal, light 40-second lingual, laser 5-second lingual, laser 10-second lingual, and laser 15-second lingual. All bonded specimens were placed in distilled water for 30 days at 37 degrees C followed by thermal cycling for 24 hours. Brackets were detached using a shearpeel load delivered by an Instron machine. The site of bond failure was examined under 10x magnification. The difference in the shear-peel bond strength between the light 40-second buccal (13.31 MPa) and the light 40-second lingual (11.95 MPa) groups was not statistically significant. The mean shear-peel bond strengths for the laser cured groups were quite similar for the 5-, 10- and 15-second laser groups (10.86, 11.32, and 10.80 MPa). The difference in mean lingual bond strength between the light 40-second and laser 5-second groups was not statistically significant (t = 1.26; P = .212). The adhesive remnant index analysis revealed principally cohesive bond failures. An increased frequency of enamel fractures at debond was noted in the lingual light-cured and 10-second laser-cured groups, at 35.1% (13/37) and 21.6% (8/ 37), respectively. All other groups displayed enamel fractures of 16.2% (6/37). A 5-second cure using an argon laser produced bond failure loads comparable to those obtained after 40 seconds of conventional light cure, with less than half the frequency of enamel fracture at debond.

Clinical Science A Longitudinal Study of Root Caries: Baseline and Incidence Data

A 34-month clinical investigation of root caries was conducted using a hospitalized, chronically-ill population. Forty-five subjects with 150 caries-free surfaces were observed for at least 12 consecutive months. Clinical measurements included diagnosis of new root and coronal caries, gingival inflammation, pocket depth, recession, and distance of new lesions from the gingival margin. The overall root caries attack rate was 1.90 lesions per 100 person-months at risk, with the greatest rate occurring during the first year of study. Mesial and facial surfaces accounted for 84% of all new lesions. Sixteen subjects accounted for 26 new lesions; nine subjects had two or more new lesions. Subjects with new root lesions were found to have lower enamel caries experience but higher root caries experience at baseline and higher scores for gingival inflammation, pocket depth, and recession compared with those who did not develop root caries.

Analysis of Site-specific Data in Dental Studies

Much attention has been given recently to issues in the statistical analysis of site data arising from clinical trials in periodontics. As pointed out by Imrey (1986) and Fleiss et al. (1987), it is unreasonable to expect sites within the same patient to respond independently, and thus conventional statistical methods are not directly applicable. In this paper we develop a procedure for comparing the percentage of sites showing a given characteristic across two or more groups of patients that accounts for this lack of independence. The procedure is a straightforward extension of the standard Pearson chi-square test. Two examples are given.

Adjustment of Frequently Used Chi-square Procedures for the Effect of Site-to-Site Dependencies in the Analysis of Dental Data

Donner and Banting (1988) presented a method of adjusting the standard chi-square test for the comparison of proportions when this procedure is applied to multiple-site dental data. The adjusted procedure allows for a comparison of two or more groups of subjects with respect to the prevalence over all sites of a specified characteristic, while taking site-to-site dependencies into account. In this paper, similar adjustments are presented for two other frequently used chi-square procedures, the chi-square test for linear trend and the Mantel-Haenszel test. Examples are given.

Examiner Training and Reliability in Two Randomized Clinical Trials of Adult Dental Caries

OBJECTIVES This report describes the training of dental examiners participating in two dental caries clinical trials and reports the inter- and intra-examiner reliability scores from the initial standardization sessions. METHODS Study examiners were trained to use a modified International Caries Detection and Assessment System II system to detect the visual signs of non-cavitated and cavitated dental caries in adult subjects. Dental caries was classified as no caries (S), non-cavitated caries (D1), enamel caries (D2), and dentine caries (D3). Three standardization sessions involving 60 subjects and 3,604 tooth surface calls were used to calculate several measures of examiner reliability. RESULTS The prevalence of dental caries observed in the standardization sessions ranged from 1.4 percent to 13.5 percent of the coronal tooth surfaces examined. Overall agreement between pairs of examiners ranged from 0.88 to 0.99. An intra-class coefficient threshold of 0.60 was surpassed for all but one examiner. Inter-examiner unweighted kappa values were low (0.23-0.35), but weighted kappas and the ratio of observed to maximum kappas were more encouraging (0.42-0.83). The highest kappa values occurred for the S/D1 versus D2/D3 two-level classification of dental caries, for which seven of the eight examiners achieved observed to maximum kappa values over 0.90. Intra-examiner reliability was notably higher than inter-examiner reliability for all measures and dental caries classifications employed. CONCLUSION The methods and results for the initial examiner training and standardization sessions for two large clinical trials are reported. Recommendations for others planning examiner training and standardization sessions are offered.

Bond strength of 4 orthodontic adhesives used with a caries-protective resin sealant

INTRODUCTION The purpose of this study was to investigate the shear peel bond strength (SPBS) and resin remnant retention after removal of orthodontic brackets bonded with 1 of 4 orthodontic adhesives (Transbond XT [3M/Unitek, Monrovia, Calif], Blugloo [Ormco Corp, Glendora, Calif], Light Bond [Reliance Orthodontic Products, Itasca, Ill], and APC Plus [3M/Unitek]) applied over a filled, resin sealant (ProSeal [Reliance Orthodontic Products]). METHODS Extracted premolars were first acid etched and then coated with the sealant used as a primer. This was followed by cementation of a stainless steel orthodontic bracket to the buccal surface with 1 of the 4 adhesive systems. Two adhesive systems (Transbond XT and Blugloo), without the filled sealant applied, were used as references. All specimens were stored in deionized water at 37 degrees C for 30 days, thermocycled for 24 hours at 30-second intervals between 10 degrees C and 50 degrees C water baths, and debonded with a universal testing machine. RESULTS AND CONCLUSIONS The 4 adhesive-sealant combination groups had mean SPBS values slightly lower than the 2 adhesive-only reference systems, but all were greater than 10 MPa (range, 10.1-15.9 MPa), which is considered a clinically acceptable bond strength. ANOVA showed a statistically significant difference (P <0.05) in mean SPBS among the 4 adhesive-sealant combinations. The most frequent site of bond failure at debonding for the adhesive-sealant combinations was within the adhesive.

Profile changes following extraction orthodontic treatment: A comparison of first versus second premolar extraction

OBJECTIVE To determine the change in the soft tissue profile following extraction orthodontic treatment with either first or second premolar extractions. METHODS This was a retrospective clinical study of 81 consecutive orthodontic patients treated with extraction of four premolars. Patients were divided into two treatment groups according to whether four first premolar teeth (PM1 treatment group, n=48) or four second premolar teeth were removed (PM2 treatment group, n=33) during treatment. Changes in the nasolabial angle and the distance of the upper and lower lips to E-plane were compared pre- and post-treatment. Age, sex, upper lip thickness, facial convexity, facial axis, upper and lower arch crowding at pre-treatment, use of molar anchorage and the amount of retrusion of the maxillary and mandibular incisor teeth during treatment were used as explanatory variables. RESULTS When facial convexity and facial axis at pre-treatment, the use of maxillary anchorage and the amount of retrusion of the maxillary and mandibular incisor teeth achieved as a consequence of treatment were taken into account, there was less than one degree (0.67°) difference between the change in the nasolabial angle in the PM1 treatment group compared to the PM2 treatment group (P>0.05). The mean change in the upper lip position relative to E-plane and the mean change in lower lip position relative to E-plane were also similar for the two groups. CONCLUSION The change in soft tissue profile following orthodontic treatment was similar regardless of whether first premolar or second premolar teeth were removed.