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Biomedical subjects

L B Messer

Publications and source records attributed to L B Messer.

At least 37 records · Page 2Linked to original sources
PubMed1988

Microleakage in class II composite restorations bonded to dentin using thermal and load cycling.

The effectiveness of a dentin-bonding agent (DBA) and a glass-ionomer cement liner (GIC) in reducing the marginal microleakage at the cervical margin of Class II posterior composite restorations was examined. The effect of load cycling on microleakage of this type of restoration was evaluated. The Class II cavities were prepared in extracted human pre-molar teeth, with the cervical margins finished approximately 1 mm below the CEJ. Combinations of DBA, GIC, and control (no liner) were used as mediators between resin and dentin. All restorations were placed incrementally with a 40-second cure per increment and finished with high-speed diamond burs. Half the samples of each treatment group received cyclical axial loading and half did not. All samples were thermocycled at 5 degrees and 55 degrees C for 500 cycles of one min each, stained (four hr) in 50% AgNO3, and sectioned following stain development. Microleakage was scored linearly along the dentin-restoration interface. All restorations exhibited microleakage which was unaffected by load cycling. Both the DBA and the GIC significantly reduced microleakage independently. When GIC was present, the additional presence of the DBA did not provide a statistically significant additional reduction of microleakage.

Adhesives↗
PubMed1988

A genetic contribution to dental caries, occlusion, and morphology as demonstrated by twins reared apart.

The heritability of dental characteristics has been systematically studied in animals, human populations, families, and twins, but not in twins reared apart. Under the assumption that environmental factors are no different for monozygotic twins reared apart than for dizygotic twins reared apart, the present study measured the genetic variance of several dental characteristics in twins reared apart. Ninety-seven subjects (44 twin pairs, three triplet sets) of mean age 40.6 years (S.D. 11.7) were examined over a six-year period by means of clinical and radiographic examinations, study models, and dental history questionnaires. Characteristics assessed retrospectively were: dentate status, treatment status, treatment/caries status, tooth size, malalignment, occlusion, and morphology. Data were analyzed by two-way ANOVA, intraclass correlations, heritability estimates, and concordance. There was statistically significant resemblance within monozygotic but not dizygotic pairs in the number of teeth present (p less than 0.001), percentage of teeth and surfaces restored (p less than 0.001), percentage of teeth and surfaces restored or carious (p less than 0.001), tooth size (p less than 0.001), and malalignment (p less than 0.009). Intercanine and intermolar arch width showed significant resemblance within both monozygotic (p less than 0.001) and dizygotic (p less than 0.01, p less than 0.05) pairs, whereas overjet and overbite showed no significant resemblance within pairs. Morphological features (Carabelli's trait and mandibular first premolar groove configuration) were more highly concordant in monozygous than in dizygous twins. This study provides new evidence for a marked genetic component to dentate status and dental caries experience and confirms previous reports of acknowledged inherited contributions to tooth size, malalignment, occlusion, and morphology.

Adolescent↗
PubMed1982

Canine eruption into grafted bone in maxillary alveolar cleft defects.

Forty-six patients with clefts of the alveolus who had received alveolar bone grafts (secondary osteoplasties) at ages 7-14 years, were studied. A total of 64 affected canines from 18 bilateral and 28 unilateral alveolar cleft patients was available. Follow up orthopantomographs were examined to determine the state of root development and spontaneous canine movement through the grafted site. The postoperative observation period ranged from 2-8 years (mean 4.3 +/- 1.5). All test canines erupted through the graft. Spontaneous eruption occurred for 27% of test canines, 17% required surgical uncovering (either bony or soft tissue), and 56% required surgical uncovering and orthodontic assistance to accomplish eruption. All patients required orthodontic treatment to accomplish arch alignment. The prognosis for canine eruption through a graft site is most favorable if the graft is performed at 1/4-1/2 canine root formation and when the patient is aged 9-12 years. The post graft observation period is very important and requires complete cooperation between the orthodontist and the surgeon.

Adolescent↗
PubMed1981

The effect of enamel surface reduction in vitro on the bonding of composite resin to permanent human enamel.

The shear bond strength between composite resin and human permanent tooth enamel was measured on unabraded tooth surfaces and after mechanical reduction of 0.1 mm and 0.6 mm of the enamel surface. There was a higher bond strength following the reduction of 0.1 mm of the surface (p less than 0.05) and 0.6 mm of the surface (p less than 0.01). Mechanical surface reduction was associated with increased residual composite at the bond site after debonding.

Acid Etching, Dental↗
PubMed1980

Long term effects of primary molar pulpotomies on succedaneous bicuspids.

Forty-three bicuspids which replaced successfully pulpotomized vital or non-vital primary molars, and twenty bicuspids, which erupted following unsuccessful pulpotomies requiring extraction of the preceding teeth, were examined for defects of position and enamel. In comparison with contralateral control teeth, test teeth in both groups showed an increased prevalence of rotation and enamel surface defects.

Bicuspid↗
PubMed1979

Long term retention of sealants applied by inexperienced operators in Minneapolis.

A clinical trial of 4047 single applications of Nuva Seal placed on the occlusal surfaces of primary molars, permanent first and second molars and premolars by 250 dental students showed that the sealants were not well retained. The sealant was fully retained on 86% of all permanent posterior teeth at 3 months, on 76% at 6 months, 58% at 12 months, 52% at 24 months and 41% at 36 months. At 4 years, complete sealant coverage was shown by 14% of primary molars, 25% of permanent molars and 68% of premolars. Permanent mandibular molars and premolars were superior to permanent maxillary molars and premolars in fully retaining sealants. Following sealant failure, i.e. providing partial coverage or missing, permanent maxillary molars and premolars were more prone to occlusal caries than permanent mandibular molars and premolars. At 4 years, caries was diagnosed in 40% of applications to permanent molars and in 9% of applications to premolars. Twelve instances of caries under apparently intact sealants were seen.

Adolescent↗