The effect of tooth extraction on periodontal ligament mechanoreceptors represented in the mesencephalic nucleus of the cat

When a force is applied to a tooth, mechanoreceptors in the periodontal ligament are stimulated. When teeth are extracted the remnants of the periodontal ligament break down and disappear, but it is not known what happens to the mechanoreceptor neurones that innervated it. The present study seeks to determine the effect of tooth extraction on the population of periodontal ligament mechanoreceptor neurones represented in the mesencephalic nucleus of the fifth cranial nerve. The incisor and canine teeth were extracted from adult cats; terminal experiments were performed between 7.5 months and 2 yr later. Recordings were made in the mesencephalic nucleus with microelectrodes, and neurones were identified in the inferior alveolar nerve that previously innervated the periodontal ligament of one of the extracted mandibular teeth. The majority of these neurones responded only to electrical stimuli applied to the edentulous ridge of the mandible in the area where the incisor or canine teeth had previously been. It was not possible to stimulate them mechanically, despite the use of large forces. A small number had reinnervated new soft-tissue sites. They could be mechanically stimulated and were found adjacent to the area in which the mandibular incisor and canine teeth had been. Thus the population of periodontal ligament mechanoreceptor neurones represented in the mesencephalic nucleus do not all degenerate after tooth extraction. As the majority of those still present do not appear to reinnervate new tissues in which they can be mechanically stimulated, it is unlikely that they have any functional role after tooth loss.     

Use of transcutaneous electroneurostimulation for enhancing the effectiveness of conduction anesthesia in dental polyclinic practice

The efficiency of mandibular conduction anesthesia was assessed in patients with inflammatory disorders in the area innervated by the mandibular nerve. In patients with conduction anesthesia induced after an electroneurostimulation session, the efficiency of anesthesia was considerably higher than in those operated on under mandibular anesthesia only.     

Comparative effectiveness of flossing and brushing in reducing interproximal bleeding

This study assesses the comparative effectiveness of three types of dental floss and toothbrushing in reducing interproximal bleeding sites, measured by stimulation with wooden interdental cleaners using the interdental bleeding index assessment method. The 119 adult subjects with gingival inflammation were randomly assigned to one of four groups at the beginning of a supervised 2 week clinical trial. The toothbrushing only group achieved a 35% reduction in bleeding sites and the three flossing groups all demonstrated dramatic reductions of about 67%. The three varieties of dental flosses were about equally effective in reducing interproximal bleeding and doubly effective as toothbrushing alone. Compared to probing, the interdental bleeding index method is considered a simplified method of assessing interproximal gingival inflammation.     

The effect of citric acid on retained plaque and calculus. A short communication

Five extracted human teeth with clinically demonstrable calculus were used. One proximal surface of each tooth was partly scaled, leaving a small amount of calculus. The crown was then cut off at the cementoenamel junction and the scaled proximal surface was divided vertically into two segments using a thin separating disk. One segment was treated by rubbing cotton pellets soaked in citric acid (pH1) over the surface for three minutes and then immersing the segment in saline to stop the reaction. The other (control) segment was treated by rubbing cotton pellets soaked in saline over the surface for three minutes. When viewed under a scanning electron microscope, the control sections displayed scaling striations, considerable surface debris, and large numbers of bacteria at the borders of the residual calculus. Citric acid-treated specimens displayed little debris on cementum or residual calculus and virtually no bacteria at the junction between calculus and cementum. The surface morphology of the citric acid-treated calculus varied from layered-like to honeycomb.     

Periodontal disease in heterosexuals with acquired immunodeficiency syndrome

We studied the prevalence and severity of periodontal disease among 181 heterosexual men and women with AIDS. Included were 167 (92%) intravenous drug users (IVDU) and 14 sexual partners of persons at risk for AIDS. Periodontal disease was seen in 71 of 78 (91%) women compared to 75 of 103 (73%) men. Gingivitis was the most severe form of periodontal disease in 7 (9%) women and 15 (15%) men. Increased severity of periodontal disease was seen in women as compared with men (P less than .001); among subjects with periodontitis, 48 (75%) of 64 women had moderate to advanced disease compared to 32 (53%) of 60 men. For individuals with periodontitis, the extent of involvement was associated with severity; 90% of subjects with advanced periodontitis had all 4 quadrants affected. Concurrent oral manifestations of AIDS, including candidiasis, hairy leukoplakia, ulcers and Kaposi's sarcoma were present in 167 (92%) subjects. We conclude that HIV-associated gingivitis and HIV-associated periodontitis are common in heterosexual men and women with AIDS and are often accompanied by other oral manifestations of AIDS. The reason periodontal disease is more severe in women is not known. Clinicians should be aware that these disorders occur in heterosexuals as well as in homosexual men. Further study will be necessary to delineate the pathogenesis of these disorders.     

A 5- and 8-year clinical evaluation of a posterior composite resin

Class I and II posterior composite resin (Ful-Fil) restorations were placed and were clinically evaluated, according to the US Public Health Service criteria, at baseline, 6 months, 5 years, and 8 years. At 5 years/8 years, alpha scores were assigned to the following percentages of restorations: 16%/31% for color match; 65%/62% for marginal discoloration; 74%/54% for cavosurface marginal discoloration; 100%/100% for axial contour; and 81%/65% for anatomic form. At 5 years/8 years, 56%/33% of Class II restorations had tight proximal contacts; 45%/44% had light contacts; and 0%/22% had no contacts. Transient postoperative sensitivity was reported in 6% of the restorations. Indirect evaluation indicated that there was an average of 64 +/- 35 microns of wear at baseline (because of overfinishing), 105 +/- 67 microns at 6 months, 217 +/- 76 microns at 5 years, and 253 +/- 82 microns at 8 years. At 5 years, three of the restorations, and at 8 years, four additional restorations, were clinically unacceptable because of recurrent caries and/or excessive wear. Final success rates of 90% and 77% at 5 and 8 years, respectively, were calculated.     

A posterior open bite

A case of bilateral posterior open bite, treated using the 'straight wire' appliance, is reported. The diagnostic problems, associated with this type of malocclusion, are discussed.     

Social class, parents' education and dental caries in 3- to 5-year-old children

The caries prevalence of 1273-, 4- and 5-y-old white children was determined with mirror and probe under natural light at mother and child clinics. The social class of the family, the educational level of the mother and that of the father were determined from a questionnaire filled in by the accompanying adult at the time of examination. Both social class and parent's education had a statistically significant influence on the caries prevalence: those in the lower social classes and with parents without tertiary education had a much higher prevalence of caries.     

A histochemical study of the effects of high doses of sodium fluoride on dipeptidyl peptidase II activity in the rat incisor ameloblast

Female Wistar rats, 3 weeks old, were given sodium fluoride in saline solution (isotonic) by intraperitoneal injection at a dose of either 0, 10 or 20 mg per kg body weight. This treatment was given 9 times over 4.5 days. After fixation by perfusion and demineralization in neutral EDTA, hemi-mandibles were sectioned in a cryostat. Sections were stained for dipeptidyl peptidase II activity, using the specific substrate Lys-Ala-MNA and the coupler Fast Blue B for histochemical localization. Staining indicative of dipeptidyl peptidase II was found in the enamel organ of the incisor, particularly in cells of the stratum intermedium and in both secretory and maturation ameloblasts. This staining was markedly reduced in ameloblasts of rats given either 10 or 20 mg sodium fluoride per kg body weight.