Ari Rajasuo

Comparison of the clinical status of third molars in young men in 1949 and in 1990

We investigated the clinical status of third molars in 876 Finnish conscripts aged 19.9 years (SD, 1.1 years) and compared the findings with data on male students of the same age from 40 years before. Significantly more partially erupted and fewer totally erupted lower third molars were found in the present study than 40 years earlier: 29% (95% confidence interval +/- 3%) versus 19% were partially erupted (p > 0.001), and 13% (confidence interval +/- 3%) versus 23% were totally erupted (p < 0.001). Fifty-eight percent of the lower third molars in the present study were clinically missing, whereas 13% (confidence interval +/- 2%) were totally erupted. The respective percentages in the upper jaw were 56% (confidence interval +/- 3%) versus 38% (confidence interval +/- 3%). Thirty-eight percent (confidence interval +/- 3%) of our subjects had one or two partially erupted third molars in the mandible and 10% (confidence interval +/- 2%) in the maxilla.

Pericoronitis and tonsillitis : Clinical and darkfield microscopy findings

OBJECTIVE Upper respiratory tract infections and tonsillitis and pharyngitis in particular increase the risk of lower third molar pericoronitis. The study was made to investigate clinical and microbiologic associations between pericoronitis and tonsillitis. STUDY DESIGN The subjects were 20-year-old Finnish male conscripts. Thirty-eight patients had tonsillitis without and 33 patients had tonsillitis with a symptom-free erupting lower third molar; 27 patients had pericoronitis but healthy tonsils. All subjects were examined clinically. Bacterial samples were taken from healthy and diseased tonsils and from healthy and diseased third molar pericoronal pockets. The microbes were classified morphologically with the use of a darkfield microscope. RESULTS Eighty-two percent of infected tonsils had deep crypts and 52% of them exudated pus compared with 36% (p < 0.001) and 0% (p < 0.001) in healthy tonsils, respectively. Infected lower third molars were less than half erupted and had on average 8.8 mm deep pericoronal pockets compared with pockets 5.5 mm deep recorded in symptom-free cases (p < 0.001). Spirochetes were more common in infected pockets than in symptom-free cases comprising 8.2% versus 3.0% of the total bacterial count (p = 0.044). Rods were more common in infected tonsils than healthy ones (8.9% versus 4.8%, p = 0.041). CONCLUSION There were similarities in morphologic microbiota of pericoronitis and tonsillitis. However, clinical findings of tonsils did not appear to link with the findings of third molars.

Effect of extraction of partly erupted third molars on subgingival microorganisms

This study was made to investigate the effect of extraction of third molars on subgingival microbes in 39 generally and gingivally healthy men with an average age of 20.2 years (SD 0.9). Microbial samples were taken from the pericoronal space of symptom-free partly erupted lower third molars and from the adjacent gingival pockets of the second molars. The samples were cultivated anaerobically. All partly erupted third molars were extracted from 20 subjects. A control group of 19 subjects was left untreated. Microbe sampling was repeated 2 and 5 months postoperatively with highly significant results. It was shown that at baseline the number of black-pigmented gram-negative bacteria and Fusobacterium species was more frequent in third molar than in second molar sites. The total bacterial count decreased significantly at the second molar sites after extraction of the third molars when compared with the control group. Before the extractions, black-pigmented gram-negative bacteria were detected in 45% of the test subjects and Actinobacillus actinomycetemcomitans in 20%. The respective postoperative figures were 30% for black-pigmented gram-negative bacteria and 10% for Actinobacillus actinomycetemcomitans. Capnocytophaga species were not affected by the extractions. The findings suggest that erupting third molars may harbor harmful bacteria that can be reduced by eradicating the foci.

Effect of Extraction of Partly Erupted Third Molars on Salivary Microbial Counts in Conscripts

Viable counts of mutans streptococci, lactobacilli and yeasts in saliva were followed for 5 months after extraction of partly erupted third molars in 49 conscripts aged 19.9 +/- 0.8 years. For controls, 27 conscripts aged 19.7 +/- 1.2 years were studied who did not have indications for third molar extractions. The microbiological analyses were made from paraffin-wax-stimulated saliva using dip-slide techniques. The results showed a statistically significant reduction of the high counts of mutans streptococci (greater than or equal to 10(6) CFU/ml saliva) and lactobacilli (greater than or equal to 10(5) CFU/ml saliva), both 2 and 5 months after extraction, when compared with the baseline values and with the controls. The extraction of partly erupted third molars did not appear to affect salivary yeast counts. We suggest that partly erupted wisdom teeth act as reservoirs for mutans streptococci and lactobacilli, in particular, and that their state of eruption must be taken into account when interpreting salivary microbiological counts.

Radiographic findings on 3rd molars removed in 20-year-old men.

In this study we assess radiographic findings characteristic of mandibular 3rd molars that had required either routine or surgical extraction. X‐ray findings relating to acute pericoronitis were also examined. The material was collected by investigating patient records and rotational panoramic radiographs of 20‐year‐old Finnish male conscripts (n = 738) treated during military service because of 3rd‐molar‐related problems. The follicle around the crown of mandibular 3rd molars with acute pericoronitis was enlarged in 19% of cases and in 13% of chronic symptom‐free pericoronitis cases (not statistically significant difference). Mandibular 3rd molars extracted surgically were more often mesially inclined than those extracted routinely (61% vs. 23%; P < 0.001), partially or totally intrabony impacted (92% vs. 66%; P < 0.001) and deep situated (on average 4.2 mm vs. 2.5 mm under the occlusal plane). Surgical extraction was also associated with the roots completely developed [92% vs. 84% of the teeth routinely extracted, odds ratio (OR) 2.6, 95% confidence interval (CI) 1.2–5.5] and with the absence of radiographic pericoronitis [around 27% vs. 39% of the teeth routinely extracted (OR 0.5, 95% CI 0.3–0.8)]. In 86% of cases the space between 2nd molar and ramus of the mandible was narrower than the 3rd molar extracted surgically, whereas this was 62% in routine extraction cases (P < 0.001). We conclude that there are some typical 3rd‐molar findings in rotational panoramic radiographs that show a need for surgical extraction.