Ultrasonic determination of gingival thickness. Subject variation and influence of tooth type and clinical features.

The objectives of the present study were (I) to determine the validity and reliability of measuring gingival thickness (GTH) with a recently developed, commercially available ultrasonic device; (II) to measure GTH in relation to tooth type and age of proband; (III) to correlate GTH with varying forms of premolars, canines and incisors. Ultrasonic measurements were performed in 200 periodontally healthy, male probands representing 3 different age groups (20-25, 40-45, 55-60 years). In the maxilla, mean GTH varied between 0.9 mm (canines, 1st molars) and 1.3 mm (2nd molars). In the mandible respective mean values ranged between 0.8 mm (canines) and 1.5 mm (2nd molars). No differences in means and standard deviations (0.36-0.39 mm) were observed in different age groups. In order to correlate GTH with other clinical parameters and form of tooth, in 42 probands of the youngest age group, presenting with no attrition or abrasion, no artificial crown restorations and (following prophylaxis) no overt gingivitis and no periodontal probing depth in excess of 3 mm, detailed clinical measurements and stone model cast analyses were performed. By stepwise multiple linear regression analysis, 24% (p < 0.0001) of the variation of GTH was explained by probing depth, recession, width of gingiva and tooth type. The ratio of the width of the crown to its length was not included into the model. When performing analysis of covariance with the subject as factor, the model was improved, now explaining 41% of the variation of GTH. In this model, the influence of periodontal probing depth was decreased, and recession was not included. It was concluded that there are individual differences in GTH (i.e., different biotypes). However, thickness mainly depends on tooth type and is correlated with width of gingiva. There appears to be no association with shape and form of the tooth. Validity and reliability of measuring GTH with the ultrasonic device was found to be excellent.

Effect of fluoride on autogenous iliac cancellous bone and marrow transplants in surgically created intrabony pockets in dogs.

The effect of the osteogenic capacity of fluoride on autogenous iliac cancellous bone and marrow transplants was studied in experimentally created periodontal defects. Eight dogs, 2 years old, weighing between 10 to 15 kg each, were used. The right side of the upper jaw served for creation of the experimental (fluoride-treated) pockets and the left side for the control (saline-treated) pockets. Fluoride treatment was carried out by a single topical application of a high concentration of fluoride in the periodontal defects and by application of a low concentration of fluoride to the bone marrow transplants. Intraoral periapical radiographs were taken immediately after implantation, and at time of sacrifice. Changes during bone healing were assessed histologically and by radioopacity measurements. The newly formed bone in the control and fluoride-treated areas did not differ in quality. Radioopacity in the experimental defects was significantly higher in comparison with that found in the control areas. The increase was probably due to greater bone formation in the fluoride-treated defects. The difference decreased with the duration of the healing intervals. Cementum was deposited in both control and experimental sites.

Radiographic assessment of proximal infrabony pocket topography.

A method for determining the topography of interproximal infrabony pocket lesions has been presented, utilizing three intraoral radiographys. Three periapical films for the urea to be examined should be taken in a standard manner, one with the central beam angulation horizontal, another at -20degrees and the third at +20degrees. Following processing, the dried films should be examined, commencing with the -0degrees film and comparing the width of the transitional zone with that of the -20degrees film and then the film exposed with the central beam angulation at +20degrees. Following this sequence, if the transitional zone decreases in width between the 0degree and -20degrees film, then the bony destruction is greater for the buccal plate. Should the transitional zone increase in width when the above sequence of examining the film is undertaken, the bone destruction is greater for the lingual plate of bone. In each case the third film will confirm the diagnosis. In the case of horizontal bone destruction in a buccolingual direction, the transitional zone will be absent or of minimal width on the 0degree film when compared with the film exposed at +20degrees and -20degrees.

Radiographs in clinical periodontal trials.

Fifty-eight patients were selected from an ongoing study of periodontal therapy at The University of Michigan. Pre-and post-treatment series of full mouth radiographs obtained by conventional paralleling long cone technique were available. Mesial and distal radiographic bone height was scored using the technique developed by Björn et al. A total of 1416 teeth were scored from the itial radiographs, and subsequently at one, two, three, and four years after the treatment. Radiographic bone height scores were compared with level of attachment and pocket depth scores for the same teeth at the same time. Statistical significance and correlation coefficients were derived using computer analysis of the data. The data were analyzed using three different data groupings: individual teeth, patient means, and half-mouth treatment methods. High positive correlations were found between initial measurements of radiographic bone height and attachment level as well as pocket depth. The correlations between changes in measurements of radiographic bone height and attachment level after treatment were markedly lower but are statistically significant. A highly significant correlation between radiographic bone heights and measurements of attachment level also appeared in follow-up data one to four years after treatment. The method of data grouping resulted in different correlation coefficients. Highest correlations were found if the data were pooled for patients. Lowest correlations were found if the data for individual teeth were analyzed. When the data were combined to produce patient scores, sample variation is reduced and correlations increase in magnitude. The generally high correlations between radiographic bone height and attachment level scores before and after treatment tend to confirm the fact that radiographic assessment of alveolar bone height using the method of Björn et al. can provide fairly accurate assessment of interproximal periodontal support.

Bone regeneration following damage by polysulphide impression material. A case report.

Two days after polysulphide rubber impressions had been taken of gold inlay cavities in 6 and 7, a 22-year-old female dental student developed a painful swelling between 5 and 6. A radiograph revealed the presence of an irregular radiopaque body within the cancellous bone of the interdental septum between 5 and 6. At operation, 1 month later, the interdental septum was seen to have been destroyed and its position occupied by impression material and inflammatory tissue. When the lesion was reopened 2 years later to correct slight recurrent pocketing, significant regeneration of bone was found to have occurred.