Adhesive resin induces apoptosis and cell-cycle arrest of pulp cells

The application of an adhesive resin near or directly over the pulp was shown to induce pulp inflammation and lack of dentin regeneration. We hypothesize that the absence of dentin bridging is due to adhesive-resin-induced apoptosis of cells responsible for pulp healing and dentin regeneration. Mouse odontoblast-like cells (MDPC-23), undifferentiated pulp cells (OD-21), or macrophages (RAW 264.7) were exposed to SingleBond polymerized for 0-40 seconds. Annexin V and propidium iodide assays demonstrated that SingleBond induced apoptosis of MDPC-23, OD-21, and macrophages. The proportion of apoptotic cells was dependent on the degree of adhesive resin polymerization. Adhesive-resin-induced death of pulp cells was associated with activation of the pro-apoptotic cysteine protease Caspase-3. Interestingly, most cells exposed to adhesive resin that did not undergo apoptosis showed cell-cycle arrest. We conclude that an adhesive resin induces apoptosis and cell-cycle arrest of cells involved in the regeneration of the dentin-pulp complex in vitro.     

Unilateral ligature-induced periodontitis influences the expression of neuropeptides in the ipsilateral and contralateral trigeminal ganglion in rats

OBJECTIVES: Expression of neuronal neuropeptides in inflammatory conditions is altered. The changes in expression of substance P (SP) and calcitonin gene-related peptide (CGRP) in ipsilateral and contralateral trigeminal ganglion (TG) neurons were investigated by immunohistochemistry one week after unilateral ligature-induced periodontitis in rats. DESIGN: A retrograde nerve tracer Fluorogold (FG) was applied into the gingival sulcus of the second maxillary molar to identify the neurons in TG that specifically innervate the inflamed gingivomucosa. In addition, neurons from the corresponding maxillary and the adjacent mandibular-ophthalmic regions in TG were analysed. RESULTS: Statistically significantly higher frequencies of CGRP-positive neurons, regardless of their size, were found in TG ipsilateral to the periodontitis (83% and 73% in FG-labelled and maxillary regions, respectively) than in the control group without periodontitis (52% and 42% in FG-labelled and maxillary regions, respectively). The frequency of small FG-labelled SP-positive neurons in the ipsilateral TG (60%) was significantly higher than in the control TG (25%). In the contralateral TG the frequency of CGRP-positive neurons in maxillary region (66%) was significantly higher than in the control group. Surprisingly, the number of SP-positive neurons in all regions of contralateral TG decreased when compared to control and ipsilateral TGs. CONCLUSIONS: Taken together, these results implicate a role of neurogenic component in the pathogenesis of periodontitis. The contralateral response in the TG could be mediated through the transmedian neurological pathways crossing in the trigeminal nuclear complex or through the systemic inflammatory reaction and the activation of the so called "neuro-immune axis".     

Short team implantation studies of periodontal dressings

A modified implantation technique was used to study the early tissue reactions to three periodontal dressings (Coe-pak, Peripac, and Wondrpak). The dressings were placed in contact with an intact non-epithelialized tissue surface for 15 minutes and 3 days. The tissue reactions were assessed by histochemical and histological techniques. After 15 minutes of tissue-material contact, the most severe tissue reactions were caused by Wondrpak. When the contact period was increased to 3 days, Peripac generally showed a more severe tissue response than Wondrpak. At both contact periods Coe-pak had caused the mildest reactions.     

Hereditary gingival fibromatosis and expression of Ki-67 antigen: a case report

BACKGROUND: Hereditary gingival fibromatosis (HGF) is a fibrotic enlargement of the gingiva. The mechanism that leads to the accumulation of abnormal amounts of gingival tissue in HGF is still unknown. The aim of this report was to present the clinical and histopathologic characteristics of a patient with gingival fibromatosis and to evaluate the proliferation of HGF fibroblasts. METHODS: We examined the proliferation rate of fibroblasts in this case by using Ki-67 immunohistochemical staining and compared the rate to fibroblasts of non-fibromatosis gingival tissues from 5 healthy patients serving as controls. RESULTS: There were no Ki-67-positive cells in the lesional tissue, and the control gingiva revealed no immunostaining. The number of Ki-67 antigen-positive epithelial cell nuclei was observed to be low in the basal cell layers of hyperplastic gingival epithelia, similar to the control group. CONCLUSIONS: In the present case, there was no increase in the proliferation rate of lesional fibroblasts observed by Ki-67 immunohistochemical staining as a proliferation marker; only the epithelium was stained. It seems likely that the underlying mechanism of HGF may be an increase in the biosynthesis of collagen and glycosaminoglycans rather than cell proliferation.     

Fracture resistance of teeth with Class II bonded amalgam and new tooth-colored restorations

This study compared the cuspal fracture resistance of posterior teeth restored with four different adhesive restorations. Fifty sound, maxillary human premolars were randomly divided into a control group and four experimental groups with 10 teeth in each. Specimens in the first group were intact teeth that were tested as unprepared. The remaining four groups received mesio-oclusodistal cavity preparations and were restored with a hybrid composite (Filtek Z250), a packable composite (Filtek P60), an ormocer (Definite) and an amalgam (SDI Permite) with an amalgam bonding agent (Amalgam Bond Plus). All groups were stored in water at 37 degrees C for 15 days and thermocycled 1000 times between 5 degrees-55 degrees C. The specimens were preloaded five times in compression to 10 kg using two metal rods that contacted only the teeth on the cuspal inclines. The teeth were then loaded occlusally in an Instron Universal Testing Machine until fracture occurred. The means of force required to fracture the teeth in each of the five groups was analyzed using one-way ANOVA and Tukey Test. The difference between the mean cuspal fracture resistance of the unprepared control teeth and those restored with amalgam groups was found to be statistically significant (p < 0.05). No significant differences in resistance to cuspal fracture were found among the restoration groups, the unprepared control group and those teeth restored with hybrid composite, packable composite and ormocer groups (p > 0.05).     

Histomorphometric and densitometric evaluation of the effects of platelet-rich plasma on the remodeling of beta-tricalcium phosphate in beagle dogs

Countless possibilities are available in maxillofacial surgery for the filling of bone defects. The best bone substitute known at present is osteogenic autogenous bone, but its use is accompanied by numerous disadvantages. The question has arisen of whether results attained with osteoconductive bone substitutes approach those achieved by the transplantation of autogenous bone. The aims of the investigation were to measure the effects in animal experiments of the growth factors to be found in the platelets on the rate of remodeling of beta-tricalcium phosphate, and on the quality of the new bone formed. Defects formed in the mandibles of 10 Beagle dogs were filled with beta-tricalcium phosphate or with a mixture of beta-tricalcium phosphate and platelet-rich plasma obtained from autogenous blood. The quality of the hard tissue formed and the effect of the platelet-rich plasma were examined by statistical analysis of the densitometric results obtained after 6 weeks and the histological and histomorphometric results obtained after 12 weeks. The densitometric study revealed that the bone formation was significantly more effective when platelet-rich plasma was used; at this stage, histomorphometric evaluation did not indicate a significant difference. After 12 weeks, however, the histomorphometric study demonstrated a significant difference in favor of the bone substitute used together with platelet-rich plasma. The results strongly suggest that use of the platelet-rich plasma suspension accelerates the remodeling of beta-tricalcium phosphate and leads to the formation of hard tissue with a quality similar to that of the autogenous bone.     

Effects of one versus two-layer applications of a self-etching adhesive to dentin of primary teeth: a SEM study

Resin composite is increasingly the material of choice for the restoration of primary teeth, and new materials with simplified procedures are increasingly being offered. Self-etching primers have been developed to simplify the bonding procedures. Some manufacturers recommend the application of these materials in two layers. However little is known about the application times. Therefore, this study evaluated the quality of the interfacial seal and the micromorphology of the hybrid layer in composite restorations bonded with one or two layer applications of a self-etching adhesive to the dentin of the primary teeth. The superfacial dentin (within 1-2 mm of dentinoenamel junction (DEJ)) on the occlusal surfaces of fourteen primary molars was exposed by a flat cut perpendicular to the long axis of the tooth. The occlusal surfaces were divided into two halves by a 1 mm deep groove in the labial-lingual orientation. The teeth were randomly divided into two groups: Group 1: Single Bond (control group) was applied according to the manufacturer's instructions on one half of the surface. On the other half of the same tooth, one layer of Prompt-L-Pop (experimental group) was applied according to the manufacturer's instructions. Group 2: the teeth received the same bonding regimes as group 1, but the experimental group had two layer application of Prompt-L-Pop. All samples were analyzed in SEM. Student's t-test was used to compare the width of the gap and hybrid layer thickness generated by experimental groups and control. There was a statistically significant difference between control (Single Bond) and the experimental groups (one or two layer application of Prompt-L-Pop) (p<0.05). Single Bond showed the best results. Two layer application of Prompt-L-Pop showed better sealing ability than one layer application of it (p<0.05). Only Single Bond presented a visible hybrid layer that had an average thickness of 3.7microm.     

Reactive oxygen species scavenging activity during periodontal mucoperiosteal healing: an experimental study in dogs

Excessive release of reactive oxygen species (ROS) in wounded tissue due to inflammation and ischaemia is a deleterious and destructive phenomenon for the healing process. Hence, scavenging of ROS is one of the essential steps in normal wound repair. In this study, we presented a profile of free radical scavenging enzyme (FRSE) activity of periodontal mucoperiosteal wounds in order to investigate ROS activity during periodontal wound healing. Mucoperiosteal periodontal flaps were elevated in the mandibular buccal region of seven dogs between the first premolar and first molar teeth, creating acute incisional wounds in the inner side of the flaps and they were replaced 30 min after elevation. Gingival samples taken from certain biopsy regions at baseline (before flap elevation), day 3, 12, 21 and 30 were processed for detection of active amounts of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPX). All enzyme activities had increased by more than 100% of their baseline levels by day 3. SOD activity decreased gradually from days 3 to 30 and reached a level lower than the baseline value. The increase in CAT activity continued until day 21, and decreased to a level higher than the baseline value by day 30. GPX also decreased from day 3, and reached a level less than its baseline value by day 30. Our results suggest that FRSEs may contribute to the detoxification of ROS during periodontal mucoperiosteal healing. This relationship may be utilized to facilitate soft tissue and/or flap management in periodontal or intra-oral treatments.     

Titanium mesh fracture in mandibular reconstruction

Mandibular reconstruction is important for providing good functional and cosmetic results after the resection of a mandibulary segment. Reconstruction plates and titanium meshes are usually used to reconstruct the bony defects in mandible. Although their complications are well known there is not a report on the fractures of a titanium mesh after mandible reconstruction in the literature. We reported a case of a broken titanium mesh after mandible reconstruction.     

Investigation of natural head posture in different head types

The aim of this study was to investigate natural head posture (NHP) in different head types. Lateral cephalograms of 99 adults (Mean age, 21.8 years +/- SD, 2.2 yrs, range between 19 and 29 yrs) were examined. Head types were determined as Hyperbrachycephal, Brachycephal, Mesocephal or Dolichocephal according to the cephalic index. Analysis of variance and the Duncan's test were performed to assess inter-group differences for the parameters. The findings revealed that, NHP was statistically not different between the head type groups. Thus, it was suggested that environmental factors during growth may alter NHP, as well as craniofacial morphology but in a different manner (i.e. degree and direction) in each head type.