NO-cGMP signaling molecules in cells of the rat molar dentin-pulp complex

By the formation of cyclic guanosine 3',5'-monophosphate (cGMP), nitric oxide (NO)-sensitive enzyme-soluble guanylate cyclase (sGC) plays a receptor role for NO within the NO-cGMP signaling cascade, which is involved in vasodilatation and neurotransmission. The hypothesis that NO-cGMP signaling molecules modulate cells of the dentin-pulp complex was investigated in rat molars by histochemical, immunohistochemical, immuno-ultrastructural, and organ bath techniques. NO synthase (NOS) I-III, the sGC alpha(2)-subunit/beta(1)-subunit, and cGMP were detected in odontoblasts and blood vessels. NOS I, sGC alpha(2), and cGMP were identified in nerve fibers. Treatment of rat molars with the NO donor NONOate (10(-5) M) increased cGMP staining intensities in blood vessels and odontoblasts, while NO synthase inhibitor L-NAME (10(-4) M) attenuated intensity of the reaction products for cGMP, suggesting an effect of endogenous NO on sGC. These correlations of patterns and alterations of cGMP staining intensities after treatment with the NO donor or NO inhibitor might represent an NO-sGC-cGMP signaling-dependent modulation of odontoblasts, blood vessels, and nerve fibers in the dentin-pulp complex.     

Cementum and dentin in hypophosphatasia

Hypophosphatasia (HPP) often leads to premature loss of deciduous teeth, due to disturbed cementum formation. We addressed the question to what extent cementum and dentin are similarly affected. To this end, we compared teeth from children with HPP with those from matched controls and analyzed them microscopically and chemically. It was observed that both acellular and cellular cementum formation was affected. For dentin, however, no differences in mineral content were recorded. To explain the dissimilar effects on cementum and dentin in HPP, we assessed pyrophosphate (an inhibitor of mineralization) and the expression/activity of enzymes related to pyrophosphate metabolism in both the periodontal ligament and the pulp of normal teeth. Expression of nucleotide pyrophosphatase phosphodiesterase 1 (NPP1) in pulp proved to be significantly lower than in the periodontal ligament. Also, the activity of NPP1 was less in pulp, as was the concentration of pyrophosphate. Our findings suggest that mineralization of dentin is less likely to be under the influence of the inhibitory action of pyrophosphate than mineralization of cementum.     

Plunging or cervical ranula. Review of the literature and report of 4 cases.

A review of the literature pertaining to plunging ranula is presented with special emphasis on the historical development of the various aetiological theories and treatment recommendations. Also 4 cases of plunging ranula are presented; three were treated by extirpation of the sublingual gland and one was treated by exteriorization of the ranula into the oral cavity. The treatment methods used here are discussed in relationship to the accepted aetiological theory.     

Effect of reducing frequency of augmented feedback on manual dexterity training and its retention

OBJECTIVE: The study addressed the impact of the frequency of tutorial-enriched augmented visual feedback, provided by a virtual simulation system (DentSim), on the skill acquisition for a cavity preparation task in novice dental students. METHODS: Thirty-six subjects were assigned to two training groups and a control group. The task consisted of a geometrical cross preparation on the lower left first molar. All subjects performed a pre-test to assess their basic skill level. The training groups received simulation feedback, enriched with tutorial information, across acquisition. One group trained under continuous augmented feedback, while a second group trained under an intermittent (66% of the time) feedback. At both 1-day and 4-month interval, subjects performed a retention test to explore learning specific effects. Two transfer tests were added to assess the extrapolation of the learned skills to an adjacent molar. All tests were performed in the absence of feedback. A control group performed all the tests, without preceding training. All preparations were graded by the simulation system. RESULTS: The training groups performed similarly across acquisition and improved with practice (ANOVA, P<0.001). After 1 day and 4 months of no practice, the training groups outperformed the control group on a retention test (ANOVA, P<0.001) and transfer test (ANOVA, P<0.001). CONCLUSIONS: Performance and learning of a cavity preparation task on a simulation unit was independent of the frequency of tutorial-enriched augmented visual feedback within the range tested. Training sessions on a simulation unit could be alternated with training sessions in the traditional phantom head laboratory.     

Dental plaque, gingival inflammation, and elevated levels of interleukin-6 and cortisol in gingival crevicular fluid from women with stress-related depression and exhaustion

BACKGROUND: The aim of the present study was to investigate the importance of stress for the development of periodontitis by comparing oral health status, proinflammatory markers, and cortisol in gingival crevicular fluid (GCF) and saliva in patients with stress-related mental depression and controls. METHODS: The participants consisted of 43 women with stress-related depression and exhaustion (Diagnostic and Statistical Manual of Mental Disorders, 4th edition [DSM-IV], with a mean age of 42.0 (+/- 9.3 SD) years, and 29 controls, with a mean age of 54.5 (+/- 2.9 SD) years. Clinical examination included the assessment of dental plaque, gingival inflammation (GI), bleeding on probing (BOP), probing depth (PD), clinical attachment level (CAL), and number of teeth. GCF was collected with an intracrevicular washing technique from four sites in each subject. Interleukin (IL)-1beta, IL-6, and matrix metalloproteinase-9 were determined with enzyme-linked immunosorbent assay and cortisol with radioimmunoassay (125I RIA). Analysis of covariance (one-way covariance analyses) was used to remove the influence of age and smoking. RESULTS: The amount of plaque was significantly higher in patients compared to controls (P<0.003). The patients had an average GI of 1.53 (+/-0.13 SD) compared to 0.89 (+/- 0.10 SD) for the controls (P< 0.001). The levels of cortisol in GCF was significantly higher in patients than in controls, 3.46 nmol/l (+/- 3.25 SD) and 0.30 nmol/l (+/- 0.25 SD), respectively (P<0.001), whereas cortisol in saliva did not differ between groups. The levels of IL-6 in GCF were significantly higher in the patients than in controls (P<0.05). CONCLUSION: Women with stress-related depression and exhaustion had more plaque accumulation, GI and increased levels of IL-6 and cortisol in GCF compared to normal controls, suggesting that depression might affect immune function, which could lead to impaired periodontal health.     

Recurrent melanotic neuroectodermal tumor of infancy: a proposal for treatment protocol with surgery and adjuvant chemotherapy

The case of a 4-month-old male infant treated with combined surgery and chemotherapy for an aggressive recurrent melanotic neuroectodermal tumor of infancy (MNTI) on the top of the alveolar process of the mandible with a long-term follow-up is presented. Initial treatment comprised conservative local excision and curettage of the mandible. After several local recurrences and because radical surgical excision would give gross functional and aesthetic mutilation, finally complete, long-lasting remission was achieved with adjuvant chemotherapy, according to a neuroblastoma protocol (10-year follow-up). The reason for this protocol was because molecular genetic studies of this tumor showed loss of heterozygosity of chromosome 1p and gain of chromosome 7q analogue to neuroblastomas. A combination of surgery and chemotherapy should be the preferred treatment in case of a recurrence MNTI because optimal functional and aesthetic outcome.     

Oral lichen planus, amalgam and other restorative materials

Mucosal lesions in the oral cavity, identical to oral lichen planus (OLP), as a consequence of contact with in particular dental silver amalgam may be due to an allergic reaction to mercury or, possibly, a toxic effect on the oral mucosa. Substitution of amalgam preferably by gold--unless sensitisation to gold exists--often results in remission, which sustains a pathogenic role of amalgam in OLP. Substitution of amalgam should be considered if the mucosal lesions correspond topographically to the restorations and epicutaneous patch testing results in a positive reaction on mercury.