Effect of a fluoride varnish on demineralization adjacent to orthodontic brackets.

Home fluoride regimens have long been used to reduce the amount of demineralization adjacent to orthodontic appliances. In the absence of patient compliance, another method of applying the fluoride must be used. The purpose of this study was to evaluate, in vitro, the ability of a fluoride varnish, Duraflor, to directly inhibit demineralization of enamel surrounding orthodontic brackets. Brackets were bonded to 36 extracted human canines and premolars with a traditional composite resin and randomly assigned to three equal groups of twelve. Group 1 served as the control with no topical application after bonding. Group 2 was treated with a single application of a nonfluoridated placebo varnish. Group 3 was treated with a single application of Duraflor. All groups were cycled in an artificial caries challenge for 1 hour two times daily for 37 days and were brushed with a medium bristled toothbrush to simulate mechanical wear of the varnish. Demineralization of enamel was evaluated in longitudinal buccolingual tooth sections using polarized light microscopy. Both average depth and area of demineralization were measured with a sonic digitizer. ANOVA (P

Enamel demineralization adjacent to orthodontic brackets bonded with hybrid glass ionomer cements: an in vitro study.

Enamel demineralization is recognized as a possible side effect of bonding orthodontic brackets with composite resins. Fluoride-releasing restorative materials have been shown to inhibit tooth demineralization. The purpose of this study was to evaluate two fluoride-releasing hybrid glass ionomer bonding agents for inhibition of enamel demineralization surrounding orthodontic brackets under two experimental conditions. This in vitro study used 72 extracted human premolars. Twenty-four teeth were bonded with Advance resionomer, 24 were bonded with Fuji Ortho LC hybrid glass ionomer and 24 were bonded with Transbond XT composite resin as the control. The teeth were cycled in an artificial caries challenge three times daily for 30 days. Half of the teeth in each group were brushed twice daily with a fluoridated dentifrice, and the other half were not brushed. Demineralization of enamel surrounding orthodontic brackets was evaluated with polarized light microscopy. Enamel lesions were photographed under maximum illumination. Images were projected, and demineralized areas were traced. Both average depth and area were measured with a sonic digitizer. Analysis of variance (P <.0001) and Duncan's test (P <.05) indicated significant differences in depth and area of demineralized enamel such that lesion size was: Transbond XT no brush > Transbond XT brush > Advance no brush = Advance brush = Fuji Ortho LC no brush = Fuji Ortho brush. The promising results of this in vitro study warrant further clinical investigation of hybrid glass ionomer adhesives as orthodontic bonding agents to minimize enamel demineralization.

The effect of microetching on the bond strength of metal brackets when bonded to previously bonded teeth: an in vitro study.

The purpose of this in vitro study was to answer the following questions for three different metal brackets: (1) when rebonding a previously bonded tooth, how do shear bond strengths compare for new brackets, new microetched brackets, and debonded microetcher cleaned brackets? and (2) how do the different bracket types compare with respect to the time required to remove composite resin from their bonding pads with a microetcher? Ninety human premolars and canines previously debonded of metal brackets were randomly assigned to 9 groups of 10 teeth each. New, new etched, and debonded etched cleaned brackets of each type were bonded with composite resin onto teeth, and the bonds tested to failure for shear bond strength. An analysis of variance and Duncan's multiple range test were used to compare bracket/enamel bond strength. Within each bracket type no significant differences were found between mean bond strengths for new, new etched, and debonded etched conditions, a finding that supports the use of microetching to clean accidentally debonded brackets. Mean times for removal of resin from bonding pads with a microetcher varied from 9.3 seconds to 11.9 seconds, with bracket (M) requiring significantly less time for removal of resin.

In vitro study of 24-hour and 30-day shear bond strengths of three resin-glass ionomer cements used to bond orthodontic brackets.

Interest in using composite resin-glass ionomer hybrid cements as orthodontic bracket adhesives has grown because of their potential for fluoride release. The purpose of this pilot study was to compare shear bond strengths of three resin-glass ionomer cements (Advance, Fuji Duet, Fuji Ortho LC) used as bracket adhesives with a composite resin 24 hours and 30 days after bonding. The amount of adhesive remaining on the debonded enamel surface was scored for each adhesive. Mesh-backed stainless-steel brackets were bonded to 100 extracted human premolars, which were stored in artificial saliva at 37 degrees C until being tested to failure in a testing machine. The hybrid cements, with one exception, had bond strengths similar to those of the composite resin at 24 hours and 30 days. Fuji Ortho LC had significantly lower bond strengths (ANOVA p < or = 0.05) than the other adhesives at 24 hours and 30 days when it was bonded to unetched, water-moistened enamel. Adhesive-remnant scores were similar for all cements, except for cement Fuji Ortho LC when it was bonded to unetched enamel. The resin-glass ionomer cements we tested appear to have bond strengths suitable for routine use as orthodontic bracket-bonding adhesives.

Type II tooth cusp occurrence asymmetry in a human monozygotic twin pair.

A Type II tooth cusp occurrence asymmetry proposed for human twins in 1974 but not observed until recently was described in a female monozygotic twin pair.

Fluoride release and shear bond strengths of three light-cured glass ionomer cements.

Little is known about the release of fluoride from light-cured glass ionomer cements when used as orthodontic bonding agents. Fluoride release from three "hybrid" light-cured glass ionomer cements was measured during a 42-day period after initial curing in an in vitro test that simulated their use as orthodontic bonding agents. On day 48, the bonded teeth were exposed for 30 seconds to a stannous fluoride gel and checked for fluoride release during the following week. One cement (BL) released the most fluoride after initial cure and after an exposure to a stannous fluoride gel on day 48. The other two hybrid cements exhibited both significantly less fluoride release than material (BL) and resembled for most of the 55-day duration the composite resin control. After the 55-day duration, shear bond strengths of the composite resin control were significantly higher than the three light-cured glass ionomer cements. The light-cured glass ionomer cements in this study released fluoride after initial curing and after exposure to a topical fluoride gel. This property may help reduce or possibly even prevent enamel decalcifications seen around bracket bases. At present, the shear bond strengths of the light-cured glass ionomer cements tested appear to be too low for routine orthodontic bonding agents.

Dental health findings in a Native American settlement.

In 1951, A. Dahlberg took casts of 82 children aged 8-17 who lived in the Sac-Fox Settlement near Tama, Iowa. In 1990, the Indian Health Service supported a survey of 44 survivors from the 1951 study. All were contacted and 23 were examined. The findings from this study were compared with findings from similar aged Sac-Fox residents surveyed in 1982, and with the residents of Iowa of a similar age surveyed in 1980. The DMFS score of the 1990 Sac-Fox samples was larger (92.4) than that for the Iowa Survey (75.3). The periodontal findings were similar in the three samples, with one exception, the category 6+mm pockets were seen more frequently in the 1990 Sac-Fox sample (13.0%) than in the 1982 Sac-Fox (8.7%) and 1980 Iowa (2.9%) samples. Mucosal lesions were observed much more frequently in the Sac-Fox 1990 (69.6%) and 1982 (65.2%) samples, compared to the 1980 sample (8.6%). The frequency of totally edentulous persons was also much greater in the Sac-Fox samples, as compared to the Iowa Sample. It appears that the 1982 recommendations for making preventive procedures available to Sac-Fox adults is still appropriate in 1990.

Change in lip vermilion height during orthodontic treatment.

The extent that the height of the vertical aspect of the vermilion of the lips decreases during treatment may determine the ultimate esthetic results for a particular patient. Marked decrease in vertical height of the vermilion may prove to be esthetically pleasing for the patient with excessive vermilion; whereas it may prove esthetically disastrous for the patient exhibiting relatively small vermilion heights before treatment. Frontal esthetics should equal the profile in importance when treatment planning. The objectives of this study were (1) to quantify vermilion height changes when incisors are retracted, (2) to determine whether the pretreatment vertical position of the upper lip on the maxillary central incisor is associated with vermilion height changes, and (3) to relate vermilion height changes to incisor retraction. Cephalometric films from 40 adult female orthodontic patients (20 Class I and 20 Class II, Division 1) were measured with dial calipers. Significant decrease (paired t tests, P < 0.05) of the mean vermilion heights of both lips occurred during treatment in the patients with Class I relationships (upper 0.75 mm, lower 0.95 mm) and Class II, Division 1 relationships (upper 0.75 mm, lower 0.60 mm).(ABSTRACT TRUNCATED AT 250 WORDS)

Craniofacial development in myotonic dystrophy.

Anthropometric, cephalometric, and dental data from 23 subjects (12 males and 11 females) afflicted with myotonic dystrophy were compared to similar data from normal subjects who participated in the Iowa Facial Growth Study. A two by two analysis of variance showed that myotonic subjects differed from normal subjects in headlength, head breadth, cephalic index, bizygomatic face width, nosebreadth, maxillary arch widths, palatal depth, anterior and posterior face heights, cranial base lengths, cranial base angles, and other cephalometric measures. Sex differences were observed for many of the variables. It is hoped that these findings will assist clinicians who treat patients having this disorder.

Anatomy of cusps of posterior teeth and their fracture potential.

Fracture of cusps on posterior teeth, especially those carious or restored, is a major cause of tooth loss, Nonfunctional cusps fracture more often than the functional; mandibular cusps fracture more often than maxillary cusps. This study examined functional and nonfunctional cusps of the maxillary and mandibular posterior teeth in four different parameters; (1) buccolingual width, (2) angle of cuspal inclination, (3) thickness of enamel, and (4) angle of inclination of the dentinoenamel junction. Measurements of functional cusps, except those in maxillary premolars established differences that may explain the frequency of frequency of fracture. These parameters of functional and nonfunctional cusps suggest that the cuspal anatomy has a relationship to the fracture potential of cusps.

Maxillary expansion: clinical implications.

Clinicians frequently expand the maxilla to correct certain malocclusions. The effects of expansion on facial structures, dentition, and periodontium are reviewed. The implications of these findings for the treatment of patients who need maxillary expansion are discussed.

A comparison of arch widths in adults with normal occlusion and adults with class II, Division 1 malocclusion.

This study compares arch widths and other cast and cephalometric measurements of 36 normal-occlusion subjects (19 males, 17 females) with 39 Class II, Division 1 subjects (20 males, 19 females). None of the subjects had received orthodontic treatment. Analysis of variance demonstrated that subjects with normal occlusion had larger maxillary molar widths, maxillary canine widths, and maxillary alveolar widths than subjects with malocclusion; only male subjects with normal occlusion had larger mandibular molar widths and mandibular alveolar widths than the malocclusion subjects; the normal occlusion and malocclusion groups had similar mandibular canine widths; and when the lower molar and alveolar widths were subtracted from corresponding upper widths, the remainders of the Class II group were negative instead of positive, contrary to the normal group. This revealed a posterior crossbite tendency in the Class II group.

Mixed-dentition mandibular arch length analysis: a step-by-step approach using the revised Hixon-Oldfather prediction method.

Prediction of tooth size--arch length discrepancies in mixed-dentition patients is an important aspect of orthodontic diagnosis. The purpose of this article is to present the clinician with a step-by-step approach for a mandibular mixed-dentition tooth size--arch length space analysis using the revised Hixon-Oldfather prediction graph.

Prediction of the widths of unerupted canines and premolars.

The purpose of this study was to develop, with simple linear regression analysis, equations that could accurately predict the mesiodistal widths of unerupted canines and premolars in both arches of the mixed dentition patient. Clinically useful prediction equations were developed and tested on a sample of orthodontic patients. Performance of the equations in patients was satisfactory. Charts and suggestions for completing a tooth size-arch length analysis in the patient with a mixed dentition were discussed.

A revision of the Hixon and Oldfather mixed-dentition prediction method.

A revision of the Hixon and Oldfather prediction method was undertaken with measurements obtained from persons who participated in the Iowa Facial Growth Study, the same group of subjects used originally by Hixon and Oldfather to develop their prediction equation. A significantly improved prediction equation was developed. A graph was made for clinical use in the prediction of mandibular canine and premolar widths in mixed-dentition patients.

Prediction of lower canine and premolar widths in the mixed dentition.

The purpose of this investigation was to determine whether, with multiple regression analysis, a more accurate method than is now available for predicting the widths of unerupted mandibular canines and premolars of mixed-dentition patients could be developed. Regression analyses were performed on data derived from 83 Caucasian subjects (42 males and 41 females) who participated in the Iowa Growth Study. Measurements were taken on plaster casts of the mandibular incisors, canines, premolars, and first molars. Measurements of the mandibular canines, premolars, and first molars were obtained from periapical radiographs taken with a long-cone technique. Newly developed regression equations for each sex had the highest correlation coefficients and smallest absolute errors of estimate when compared to previously published methods. The new equations and previous prediction methods were tested on a sample of 55 orthodontic patients (23 males and 32 females). The newly developed equations were also the most accurate method of prediction in the orthodontic patient sample.

Prediction of the mesiodistal widths of maxillary permanent canines and premolars.

Multiple regression equations for prediction of the mesiodistal widths of the maxillary canines and premolars were developed for the right and left sides of the arches of males and females. The equations were developed from longitudinal data taken from ninety-two Caucasian children (forty-six boys and forty-six girls) who participated in the Iowa Growth Study. The multiple regression equations, when compared with three currently used methods of prediction, were the best predictors. The newly developed equations and other prediction methods currently in use were tested on longitudinal data taken from a sample of forty-three Caucasian orthodontic patients (sixteen males and twenty-seven females). Again, the multiple regression equations had the best performance.