Management of osteonecrosis of the jaws induced by radiotherapy in oncological patients: preliminary results.

OBJECTIVE: Osteoradionecrosis (ORN) is a bone aseptic necrosis which develops on post-irradiated bone tissue of patients who underwent radiotherapy for head-neck tumors. The mandible presents a higher risk to develop ORN, if compared to the maxillary bone, due to its lower vascularization. The aim of the present study is to clinically assess the regenerative ability by the epithelial and connective tissues, in response to ORN onset. PATIENTS AND METHODS: Authors have verified the importance of the surgical-pharmacological treatment, as an effective protocol for eliminating the exposed bone sequestration, as well as the teeth eventually damaged by the radiotherapy, assessing that the epithelium can regenerate only on healthy and vital tissues. RESULTS: The reported patient underwent resection of a portion of the left mandible with an incomplete healing after the surgery. A second curettage was scheduled in order to remove the bands of necrotic tissue and to obtain a clinical remission of symptoms. CONCLUSIONS: In patients undergoing radiotherapy, the dental surgeon should be able to give an early diagnosis of the dental and maxillofacial related pathologies; he should also detect all the possible infective sources and administer any possible treatment in a short time, before the beginning or the prosecution of radiotherapy.

Changes in the composition of human unstimulated whole saliva with age.

The aim of this study was to evaluate changes in the concentration of certain components of human unstimulated whole saliva during aging, in order to better understand the role played by aging in oral health. In particular, we studied total protein concentration, alpha-amylase activity, sialic acid content and calcium and phosphorus concentrations in 100 healthy subjects of both genders, aged between 10 and 80 years, who were subdivided into four groups according to their age: 10-25 years, 26-40 years, 41-65 years, and 66-80 years. Other than sialic acid, the concentrations of the components studied were not affected by age. There was a significant negative correlation between sialic acid content and age. Our data indicate the presence of a decreased submandibular/sublingual function with aging, thus suggesting the possibility of a concomitant reduction in the modulating action of unstimulated whole saliva on the oral flora.

Biochemical modifications of human whole saliva induced by pregnancy.

OBJECTIVE: To assess human unstimulated whole saliva components during pregnancy, to determine the relation, if any, between pregnancy and oral health, particularly total protein concentration, alpha-amylase activity, sialic acid content and calcium and phosphate concentrations were evaluated. DESIGN: Cross-sectional study. PARTICIPANTS: Forty-five healthy primigravid women; 15 nonpregnant women acted as controls. RESULTS: 1. A higher total protein content at 10 and 21 weeks of gestation with respect to the controls and to pregnant women at 40 weeks; 2. a higher alpha-amylase activity at 10 and 21 weeks of gestation compared with the controls and to pregnant women at 40 weeks; 3. an increased sialic acid content at 21 and 40 weeks; 4. decreased calcium and phosphorus concentrations at 21 and 40 weeks of gestation. CONCLUSIONS: Pregnancy modifies saliva composition. This could play a pivotal role in the incidence of pregnancy-induced dental caries.

Osteoconduction exerted by methylpyrrolidinone chitosan used in dental surgery.

Surgical wounds from wisdom tooth avulsions were medicated with freeze-dried methylpyrrolidinone chitosan, a gel-forming resorbable biopolymer obtained from crab chitosan by chemical modification. Methylpyrrolidinone chitosan promoted osteoconduction and the space left after avulsion was filled with newly formed bone tissue, which conferred desirable mechanical and physiological characteristics to the healed would site. Morphological evidence obtained from biopsies confirmed the radiographic data. Methylpyrrolidinone chitosan was progressively depolymerized by lysozyme and was no longer detected 6 months after surgery. None of the 10 patients reported adverse effects over one year of observation.

Evaluation of biocompatible osteoconductive polymer activity and biocompatibility for minor oral surgery in animals and humans.

The speed of recovery with and biocompatibility of biocompatible osteoconductive polymer used for minor oral surgery were investigated in animals and humans. Histological and radiological follow-up of graft sites and experimental mandibular bone loss was performed in 20 rabbits. Evaluation of X-rays showed no notable difference between the treated and control animals; however, biopsies 60 days after surgery showed that those animals treated with biocompatible osteoconductive polymer did not have any interposition of connective tissue between the polymer and the new bony tissue whereas the control samples did. Radiographic follow-up of the human patients at 30 and 60 days following molar extraction showed more bone regeneration in all patients treated with the polymer compared to the controls. The results showed that the use of biocompatible osteoconductive polymer to fill secondary surgical extraction cavities provided fast prosthetic rehabilitation for the patients.

The effect of membrane lipid molecular species on rat brain base-exchange reactions: an appraisal of phosphatidylserine and of polyunsaturated phosphatidylcholine.

Rat brain microsomal membranes were solubilized with octyl glucoside and reassembled by removing the detergent. The composition of reconstituted membranes was modified by adding exogenous lipid to the detergent-membrane mixtures. The base-exchange reactions were sensitive to these procedures. The inhibiting or activating capacity of added lipid was related to the charge of polar head groups; indeed, the addition of phosphatidylserine always resulted in inhibition and that of phosphatidylcholine very often in activation. The addition of phospholipid possessing unsaturated acyl chains inhibited less (or activated more) serine and choline base-exchange than the addition of saturated species. It is concluded that phosphatidylserine and polyunsaturated phosphatidylcholine have opposite effects on base-exchange.

[Disinfection of toothbrushes. Experimental research]. / Disinfezione degli spazzolini dentali. Ricerca sperimentale.

Aim of the present paper is to verify in a vitro study, the possible disinfection of the toothbrushes with an UV instrument (Dentec 4000). The modifications in microbic concentration after a contamination with microbial suspension of oral cavity have been estimated.

Fusion of liposomes and rat brain microsomes examined by two assays.

Liposomes are prepared from rat brain microsomal lipid and loaded with either Tb3+ or dipicolinic acid (DPA) to test fusion with the Tb-DPA assay. They are also loaded with octadecyl Rhodamine B chloride (R18) to test fusion with the R18 assay. The addition of either Ca2+ or Mg2+ to loaded liposomes develops fluorescence with both assays. The fluorescence elicited by Mg2+ is similar to that elicited by Ca2+ if assessed with R18, but much higher if determined by Tb-DPA. The Ca2(+)-dependent fluorescence of the Tb-DPA complex is not suppressed by the addition of EDTA, and therefore it is internal to vesicles. The contrary is true for the Mg2(+)-dependent fluorescence. Rat brain microsomes can be disrupted by adding octylgucoside and reconstituted by removing it by dialysis. We use this procedure to load microsomes with DPA. This allows the use of the Tb-DPA assay for testing the fusion of rat brain microsomes. Reconstituted microsomes fuse with liposomes. This fusion has characteristics similar to those of liposome-liposome fusion. However, no microsome-microsome fusion could be detected with either method. The two methods give different results, owing to the chemical properties of the assays. Indeed Tb-DPA implies the retention of vesicle content, whereas this is not required by the R18 assay.

Valproic acid and bicuculline affect the formation of glycerolipid in rat brain.

To ascertain the effects of bicuculline and of sodium valproate on the incorporation of glycerol into rat brain lipid, rats were divided into 5 groups: (a) controls; (b) treated with sodium valproate (400 mg/kg body wt); (c) treated with bicuculline (12.5 ?mol/kg body wt); (d) treated with sodium valproate as in (b) + bicuculline as in (c); and (e) treated with bicuculline (25 ?mol/kg body wt). Only rats of group (c) had seizures, which lasted until the end of the experiment. Each animal received 20 ?Ci of [2-(3)H]glycerol by intraventricular route and was sacrificed 12 min afterwards. Hippocampi and cerebella were taken and lipid extracted and separated by chromatography. The type of treatment influenced very much the fate of injected, labeled glycerol. Indeed, total recovered radioactivity increased following either convulsions or the administration of valproate, whereas both treatments decreased the amount of radioactivity incorporated into lipid. These effects were more evident in cerebella than in hippocampi. The distribution of radioactivity among lipid classes (diglyceride, triglyceride and total phospholipid) was also affected by seizures, which decreased the labeling ratio phospholipid/neutral lipid. The distribution of radioactivity among phospholipid classes was influenced by bicuculline (both at convulsant and non-convulsant doses) and these effects were sometimes antagonized by valproate. We conclude that some effects of bicuculline are exerted through the systemic modifications due to seizures and that other effects are probably connected to neuronal hyperfiring. The data reported in this paper are consistent with both mechanisms of action proposed for valproate, i.e. increased membrane permeability and modifications of GABAergic systems.