Gingival resistance to probing forces. I. Determination of optimal probe diameter.

This paper presents the results of a study designed to determine (1) if advancement of a periodontal probe under a given force against healthy gingiva differed from its advancement under a similar force, against inflamed gingiva, and (2) to select the diameter which best distinguishes healthy gingiva from that which is inflamed to varying degrees. The teeth of eight beagle dogs were cleaned three times per week for two months until a Gingival Index (GI) of 0 and gingival fluid flow (GFF) of 9 or less, as measured by the Periotron, were obtained. Probes of diameters 0.4, 0.6, 0.7, and 0.8 mm were advanced perpendicularly against the attached gingiva in the incisor, premolar, and molar regions by an electromechanical device which simultaneously plotted force versus displacement following initial contact of the probe tip with the gingiva. These forces ranged from 0.1 to 0.9N. This process was repeated in the same animals following cessation of plaque control measures when the GI reached a value of 1 and GFF reached levels of 10 to 19. It was repeated again following placement of an irritating ligature when GI reached 2 and GFF greater than 20. An analysis of covariance showed significant differences between all three levels of health and disease for all probe diameters. F values for the 0.6 mm probe were highest at all probing forces indicating that this diameter most consistently discriminated variation of gingival health status.

Cranial CT in children and adolescents with diabetic ketoacidosis.

To determine the effects of diabetic ketoacidosis on the brain, we studied nine consecutive patients between the ages of 6 and 17 years by performing cranial CT on three occasions: on admission, before treatment; 6-8 hr after beginning treatment; and 7 days after admission. Both the pretreatment scans and those at 6-8 hr showed significantly reduced size of the lateral and third ventricles in comparison with the 7-day scans. A comparison of the pretreatment scans with those done at 6-8 hr showed no statistically significant differences. We conclude that the cerebral swelling of diabetic ketoacidosis is usually present before treatment.

Clinical performance of sealed composite restorations placed over caries compared with sealed and unsealed amalgam restorations.

The 2-year clinical evaluations of paired occlusal restorations are presented. Each study participant received a sealed composite restoration placed over a carious lesion and either a traditional outline-form (unsealed) amalgam or an ultraconservative sealed amalgam restoration. Caries was removed before placement of both types of amalgam restorations. No important clinical differences developed among the three groups of restorations.

Gingival and bacterial plaque response to instrumentation, oral hygiene instruction and nutritional therapy.

Thirty-three male subjects participated in a study to examine the effect of supplements of multiple vitamins and minerals, local therapy (periodontal instrumentation and oral hygiene instruction) and a combination of both on gingival inflammation and bacterial plaque formation. Subjects were given either multivitamin and mineral supplements or placebos on a double-blind basis for 21 days. On Day 7, the mandibular incisors were instrumented, and each subject was instructed in brushing and flossing. Observations were taken at Days 0, 7 and 21. There was a significant (P = 0.004) effect from micronutrient supplementation at Day 7 on the gingival index but no significant effect on the plaque index. On Day 21 there was no statistical superiority noted for the supplemented group in respect to either the gingival or plaque index, although the gingival index approached significance (P = 0.062).

A practical evaluation system for preclinical restorative dentistry.

This paper describes an attempt to build a functional evaluation system incorporating several aspects of the evaluation process that have been advocated in educational research. The system--which employs performance criteria, analytical grading, rater calibration, student self-evaluation, mark-sense grading forms, and computer tabulation--has been in effect for six years at the Medical College of Georgia School of Dentistry. The main advantages of this approach are prompt, specific feedback to students concerning their performance on practical exams and diagnostic aids to course directors. In addition, rater calibration has resulted in interrater reliability usually around 0.80 or higher. The major disadvantages of the system are the faculty time required and dependence on a computer.

A thermal shock test for porcelain-metal systems.

Certain conclusions may be made on the basis of this study. 1) The effects of alloy, porcelain, and alloy-porcelain interaction on the temperature differential required to induce porcelain crazing are significant. 2) The effect of porcelain is the most significant determinant of delta T values. 3) Under thermal shock conditions, the crazing resistance of porcelains decreases in the order: V less than [C, N, W] greater than B, where C greater than W. 4) For the conditions used, the thermal shock test is a sensitive discriminator of the crazing resistance of porcelain-metal systems.

Centric relation: a comparison of muscle-determined position and operator guidance.

Fifteen subjects were used to determine direction and magnitudes of shifts in condylar position when interocclusal records were made by biting hard or easy on a leaf gauge or wax. Electromyographic recordings were made of the temporal and masseter muscles during interocclusal registrations to determine which muscles were most active in seating the condyle when the leaf gauge was used. Results indicated no significant difference in condylar position superoinferiorly between registrations. Biting hard on a leaf gauge caused a significantly more posterior position of the condyle. When this technique is used for obtaining interocclusal registrations, the temporal muscles are more active than the masseters.

Cephalometric analysis: comparisons between maximum intercuspation and centric relation.

Cephalometric analyses were made of forty-six preorthodontic patients with the mandibular teeth in maximum intercuspation. A Centric-Ceph was used and the analysis was repeated on these patients with the mandible in centric relation. The following conclusions are drawn: 1. No clinically useful prediction may be made from cephalometric radiographs concerning the amount of mandibular deflection from centric relation to maximum intercuspation of teeth. 2. There are differences in cephalometric measurements with the mandible in the two different positions. However, with the exception of a few cases, the differences are slight. 3. The individual cases that have the largest discrepancies tend to be Class II malocclusion cases. The orthodontist should be aware of those cases and be prepared to articulate them for diagnosis.

Peer review of a dental curriculum: how one school did it.

The Curriculum Committee of the Medical College of Georgia implemented a formal course-by-course review of their entire dental curriculum after first adopting positions with respect to faculty philosophical concerns. The strategy adopted was to evaluate the articulation of the various courses into a coherent whole by using reviewers who taught related courses but were outside the particular department or discipline. In general, findings indicated a satisfactory degree of articulation. Some reviewers reported serendipitous outcomes for themselves as a result of reviewing the courses of others.

Movement of abutments by removable partial denture frameworks with a hemimaxillectomy obturator.

A laboratory experiment was conducted to measure the amount of movement in each of two directions on each of seven teeth, induced by three common designs of retainer, under both splinted and unsplinted conditions. An analysis of variance on a four-way, completely crossed, fixed-effects model showed significant main effects for design, splintedness, and teeth involved. Also of significance were the interactions between the factors of splintedness and teeth and between design and splintedness. Most of the variability in tooth movement was due to differences among the seven teeth (49.3 per cent of variance) and to the interaction of splintedness and teeth (20.2 per cent of variance).