Optic neuritis in Singapore

INTRODUCTION

Optic neuritis (ON) is the commonest optic neuropathy encountered in the younger group of patients from the Singapore Neuro-Ophthalmology Study Group. Previous surveys in Asia and our study suggest that ON in Singapore differs from that in Western populations where the majority of cases are associated with multiple sclerosis (MS).

METHODS

Patients satisfying our entry criteria for ON seen between September 2002 and June 2004 were enrolled in the study. The data collected was recorded in a central database and analysed two years later.

RESULTS

The majority (60 percent) of our patients had anterior ON with optic disc swelling (papillitis), were idiopathic in 49.1 percent, and associated with MS in only 25.5 percent. Bilateral cases comprised 16.4 percent of our series and were usually of the anterior variety and mostly idiopathic, although it is still essential to rule out secondary causes. Recurrent ON is indicative of an underlying disease process.

CONCLUSION

The pattern of ON as seen in Singapore differs from that reported in Caucasian studies and from the seminal Optic Neuritis Treatment Trial. We found a higher incidence of optic disc swelling, i.e. anterior ON (papillitis), and a lesser association with MS; visual recovery is similarly good but our recurrence rate is lower.

Expression of p21 and p53 in rat gingival and human oral epithelial cells after cyclosporine A treatment

BACKGROUND AND OBJECTIVE

Expression of p21 and p53 were examined, at gene and protein levels, in edentulous gingival epithelial cells from rats and from a human oral epidermoid carcinoma cell line, OECM1, after cyclosporine A therapy.

MATERIAL AND METHODS

In vivo: 20 partially edentulous SD rats were assigned into cyclosporine A feeding and control groups. After the rats were killed, p21 and p53 in gingiva were evaluated by reverse transcription-polymerase chain reaction and immunohistochemistry. In vitro: after cyclosporine A treatment, p21 and p53 of OECM1 cells were evaluated by western blot and the luciferase assay. The distribution of OECM1 cells in each phase of the cell cycle was evaluated by flow cytometry.

RESULTS

The mRNA expression of p21 was significantly higher in the cyclosporine A group than in the control group. A greater number of positive anti-p21-stained cells were observed in the gingival epithelium of the cyclosporine A group than in the control group. Significantly higher levels of p21 protein and activity were observed in OECM1 cells after cyclosporine A treatment than in cells without treatment. A relative increase of cells in G0/G1 phases, and a decrease of cells in G2/M phases, were observed in OECM1 cells after cyclosporine A treatment.

CONCLUSION

In the present study, higher p21 mRNA and protein expressions were observed after cyclosporine A treatment. Thus, an up-regulation of p21 expression, via a p53-independent pathway, by cyclosporine A in gingival and oral epithelial cells was suggested.

Cyclosporin-A inhibits the expression of cyclooxygenase-2 in gingiva

BACKGROUND AND OBJECTIVE

Various inflammatory mediators are involved in the development of cyclosporine A-induced gingival overgrowth. In this study, the gingival expression of cyclooxygenase-2 after cyclosporine A therapy was examined in vivo and in vitro.

MATERIAL AND METHODS

After edentulous ridges on maxilla were established, 21 Sprague-Dawley rats received cyclosporine A daily for 4 wk, and a further 21 rats received solvent. After the rats were killed, the expression of cyclooxygenase-2 mRNA, interleukin-1beta mRNA, tumor necrosis factor-alpha mRNA, and interleukin-6 mRNA was examined in the edentulous gingiva. The expression of cyclooxygenase-2 protein and the production of prostaglandin E2 were also evaluated.

RESULTS

In cultured human gingival fibroblasts and epithelial cells, the expression of cyclooxygenase-2 mRNA was measured after treatment with cyclosporine A. Significantly lower expression of cyclooxygenase-2 and interleukin-1beta mRNA, but higher interleukin-6 expression, were observed in gingiva from cyclosporine A-treated rats than in those from the control rats. Significantly less prostaglandin E2 production was observed in cyclosporine A-treated rats. Immunohistochemistry revealed that fewer gingival stromal cells were positively stained for cyclooxygenase-2 in cyclosporine A-treated rats. In cultured cells, significantly less cyclooxygenase-2 mRNA was detected after treatment with cyclosporine A.

CONCLUSION

The expression of cyclooxygenase-2 was lower in the plaque nonretentive gingivae and the in vitro gingival cells upon treatment with cyclosporine A. Thus, we propose that cyclosporine A inhibits the expression of gingival cyclooxygenase-2.

Expression of fascin in oral and oropharyngeal squamous cell carcinomas has prognostic significance - a tissue microarray study of 129 cases

AIMS

To elucidate the role of fascin in oral and oropharyngeal squamous cell carcinoma (OSCC) by correlation with clinical parameters.

METHODS AND RESULTS

Paraffin sections using tissue microarrays of 129 patients with OSCC were investigated immunohistochemically. Fascin protein was overexpressed in OSCC cells compared with their non-neoplastic epithelial counterparts. For evaluating the intensity of fascin, 39 (30.2%) were classified as weakly immunoreactive, 76 (58.9%) as moderate reactive and 14 (10.9%) as intensely reactive. For evaluating the distribution of fascin, 64 (49.6%) were classified as < 55% and 65 (50.4%) were classified as >/= 55%. Fascin protein expression was correlated with size or extent of the tumour (P < 0.001), positive lymph node metastasis (P < 0.001), distant metastasis (P = 0.014) and clinical staging (P < 0.001). The immunoreactivity scores of fascin in OSCC were variable but showed significant correlation with histological grade, clinical TNM system and stage.

CONCLUSION

Expression of fascin protein may play an important role in progression of OSCC. Overexpression of fascin contributes to a more aggressive clinical course and suggests the potential of fascin as a new molecular target for therapeutic intervention.

Dynamic recording of irrigating fluid distribution in root canals using thermal image analysis

AIM

To investigate the influence of the size and the depth of insertion of irrigating needles, and the diameter of the master apical file on flow distribution during fluid irrigation in root canals.

METHODOLOGY

Stepback canal instrumentation was employed on seven extracted human single canal teeth. The size of the master apical files ranged from sizes 25, 30, 35, 40, 45, 50 to size 80 within the seven teeth, respectively. A thermal imaging system (ThermaCAM; National Instruments Co., Austin, TX, USA) was used to record the dynamic fluid distribution following root canal preparation. The dynamic fluid distribution was analysed during irrigation by insertion of different irrigating needle tips (23, 25 and 27 gauge) at various depths (3, 6 and 9 mm) from the root apex. The whole process of irrigation was recorded by a video camera and analysed by two observers separately. The success of the irrigation process was defined when the irrigant was able to flow into to the apical region immediately after injection.

RESULTS

The aqueous irrigant was flushed into the apical region when a size 27 gauge irrigating needle was placed into a size 30 canal at a point 3 mm from the apical stop. When the same needle tip was placed 6 mm from the root canal apex, successful irrigation was achieved only in the canals prepared to size 50 or larger. When a size 25 gauge irrigating needle was placed 3 mm from the working length, the canal size had to be no <45 to allow for successful irrigation. When a size 23 gauge needle was placed at the same position, the canal needed to be prepared to size 50 to allow thorough irrigation of the apex. At 9 mm from the apical stop, none of the irrigating needles could achieve successful irrigation of any canal size.

CONCLUSION

The flow distribution of root canal irrigation can be affected adversely by large diameter irrigating needles, by greater distances between the needle tip and the apical stop, and by narrow root canals.

Healing following tooth extraction in cyclosporine-fed rats

Healing after tooth extraction was studied in rats treated with cyclosporine-A (CSA) for four weeks. Sixty male Sprague-Dawley rats were assigned to one of three groups of 20 rats each. The maxillary right molars were extracted from two groups; the third group served as a non-extraction control. The non-extraction group and one extraction group (vehicle control) received the solvent mineral oil daily, and the other extraction group received 15 mg/kg CSA in mineral oil. Five rats from each group were killed 5, 10, 14 and 28 days after extraction and samples analyzed histologically. On days 5 and 10, bone volume was significantly lower and marrow volume significantly higher in both extraction groups than in the non-extraction group. The fractional-formation surfaces were significantly lower in the extraction groups than in the non-extraction group on day 5 only. Osteoid volume was significantly higher in the extraction vehicle control group than in the other two groups on days 10 and 14; however, the osteoid volume was higher in the CSA group than in the other two groups on day 28. On days 14 and 28, bone volume was lower and marrow volume higher in the CSA group than in the extraction vehicle control and non-extraction groups. On day 28, bony surface areas were significantly greater in the CSA group than in the extraction vehicle control and non-extraction groups. Soft-tissue evaluation showed significantly greater epithelial areas, connective tissue areas and total tissue areas in the CSA group than in the extraction vehicle control group on day 28, but not on day 14. These data suggest that CSA may influence healing of both the gingival tissue and the alveolar bony sockets in the tooth-extraction wound. Further detailed study is needed to identify the mechanisms responsible.

Mandibular second molar periodontal status after third molar extraction

BACKGROUND

Extraction and treatment of third molars have been cited as causing periodontal problems. To evaluate the long-term effects of third molar extraction on the periodontal health of the mandibular second molar, a comparison of the periodontal status was performed around 2 groups of mandibular second molars, with and without third molar extraction.

METHODS

A total of 312 sites in 57 adult periodontitis patients were examined and the buccal and lingual locations of the mesial and distal root surfaces around the second molars were recorded. Two-hundred and thirty-two sites were experimental teeth; i.e., third molars had been surgically removed more than 5 years ago, 80 sites served as control molars; i.e., congenitally missing third molars. Clinical periodontal parameters including probing depth, attachment loss, and gingival recession and radiographic intrabony level were measured. The effects of the surgery and the examination (buccal or lingual) locations on the measurements were statistically analyzed.

RESULTS

Neither extraction history nor examination location affected the probing depth on mesial surfaces. However, significant effects of the surgical history on the probing depth were observed on the distal surfaces. Similar results of greater attachment loss and radiographic alveolar bone loss were observed only at the distal sites of the experimental group. In addition, the increased radiographic bone loss was only found at the distal sites (adjacent to the surgical location) and not at the mesial sites (distant from the surgical location) on the experimental group.

CONCLUSIONS

In this study, greater periodontal breakdown, including probing depth, attachment loss, and radiographic alveolar bone loss, was found at the distal sites, but not at the mesial sites, of the experimental molars where the third molar was surgically extracted compared with the control teeth (no surgery). In the experimental molars, more radiographic bone loss was found at the sites adjacent to the surgical location than at the sites distant to the surgical location. Therefore, we suggest that the surgical removal of the mandibular third molar may lead to a periodontal breakdown on the distal surface of the second molar. Periodontal re-evaluation after the initial healing of third molar extraction is indicated.

A histomorphological investigation of the effect of cyclosporin on trabecular bone of the rat mandibular condyle

The effect of cyclosporin A (CSA) on the condylar trabecular bone was evaluated by microscopy. Twenty, 5-week-old male Sprague-Dawley rats were divided into a treated and a control group. Animals in the treated group received CSA, 15 mg/kg body weight, by gastric feeding daily for 4 weeks; controls received the vehicle only. Five animals from each group were killed at the end of weeks 2 and 4. After histological processing, 10 tissue sections from the mid-part of the mandibular condyle were examined. Generally, a histopathological osteopenia was observed around the condyle after CSA treatment, especially at the end of week 4. In the control animals, the trabecular bone volume steadily increased from weeks 2 to 4 (from 0.46+/-0.07 to 0.61+/-0.07 mm(3)/mm(3)). However, the bone volume was significantly less in the CSA group than in the control group at both times (0.33+/-0.02 vs 0.46+/-0.07 and 0.26+/-0.07 vs 0.61+/-0.07 mm(3)/mm(3) for CSA vs control group at the end of weeks 2 and 4, respectively). Conversely, an increased marrow volume was observed in the CSA group at both these times (0.60+/-0.02 vs 0.42+/-0.08 and 0.71+/-0.06 vs 0.31+/-0.06 mm(3)/mm(3) for CSA vs control group at the end of weeks 2 and 4, respectively). Decreases were also observed in trabecular thickness, osteoid seam width, osteoid volume and cortical bone width. Because trabecular bone mass, osteoid mass and cortical bone thickness all showed a decrease after CSA at both times, an inhibitory effect of CSA on trabecular bone formation in the mandibular condyle is proposed.

Cyclosporin-induced gingival overgrowth at the newly formed edentulous ridge in rats: a morphological and histometric evaluation

BACKGROUND

Since cyclosporin A (CsA)-induced overgrowth seldom occurs at sites distant from teeth, the periodontal ligament has been considered significant. The aim of this study was to examine overgrowth occurrence at the edentulous ridge--the sites without the ligament--after CsA therapy in rats.

METHODS

After extracting all right maxillary molars, 16 Sprague-Dawley rats underwent a 2-week healing period. The animals were separated into CsA and control groups. CsA rats received 15 mg/kg of CsA by gastric feeding for 4 weeks, while the control group received only mineral oil. At the end of study, all animals were sacrificed and stone models were immediately obtained by rubber-based impressions. The edentulous ridge morphology, including the bucco-lingual width and the vertical height, was measured on the models. For histometry, 10 sections were selected from the edentulous ridge of each animal after undecalcified tissue preparation. The soft tissue areas of the edentulous ridge and the trabecular bone morphology of the dental alveolus were measured.

RESULTS

CsA therapy produced a significant increase of the ridge width and height, measured from the stone models, when compared to the control group. Under histometry, CsA resulted in a significant increase of the epithelium, connective tissue, and total soft tissue areas. The measured trabecular bone volume was affected by both examining factors: the drug therapy and the location of the dental alveolus. CsA therapy produced a significant loss of bone volume but a significant increase of the bone-specific surface area. Although the mean osteoid volume was similar between CsA and control groups, a significant decrease of the fractional formation surface in the CsA group was revealed.

CONCLUSIONS

An enlarged edentulous ridge and an altered dental alveolar bone morphology were observed in CsA-treated animals at the end of the study; therefore, we suggest that CsA may induce not only a soft tissue overgrowth but also an alveolar bone alteration at the edentulous ridge. The hypothesis that tooth or periodontal ligament is an essential component for the overgrowth development is questioned.

Effects of cyclosporin A on dental alveolar bone: a histomorphometric study in rats

BACKGROUND

We have previously reported cyclosporin A (CA)-induced osteopenia around the dental alveoli of the mandibular incisors of rats. The drug-induced tooth displacement and the regional anatomical complexity around the mandibular incisors might complicate the local effects of CA. Therefore, the purpose of this study was to evaluate the dental alveolar bone histomorphology around maxillary secondary molars in CA-treated rats and to further elucidate the effects of CA on the dental alveolus.

METHODS

Twenty Sprague-Dawley rats were assigned to a CA and a control group. Animals in the CA group received CA (15 mg/kg) daily and the control rats received only mineral oil. At the end of weeks 2 and 4, five animals in each group were sacrificed. Dental alveoli around the maxillary second molar region were frontally sectioned and stained with toluidine blue by undecalcified histological processing. Ten serial tissue sections, 80 microm apart, were selected for histometric evaluation. Bone volume, bone-specific surface, and osteoid formation were measured at buccal, apical, and palatal locations in dental alveolus.

RESULTS

Overall bone mass in dental alveolus decreased more in the CA group than in the control group at both observation intervals. All histometric measurements, except the bone-specific surface, were significantly affected by the alveolar location (palatal, apical, and buccal) and CA therapy (P= 0.004 and <0.001, 0.001 and <0.001, 0.004 and <0.001 for drug therapy and location of the dental alveolus in bone volume, marrow volume, and the ratio of bone surface to volume, respectively). Decreased bone volume, but increased marrow volume, were noted in the CA group compared to the control group. Although the alveolar bone surface area did not differ between the CA group and the control group, greater alveolar surface-to-volume ratio was noted in the CA group. For osteoid, more decreased volume, seam width, and fractional formation surface were observed in the CA group compared to the control group (P <0.001, <0.001, and = 0.046 in osteoid volume, seam width volume, and formation surface, respectively).

CONCLUSIONS

Because the bone mass and the osteoid formation in the dental alveolus around the maxillary molar region showed a decrease after CA exposure, we conclude that this drug has inhibitory effects on the dental alveoli.

Does nifedipine aggravate cyclosporin--induced gingival overgrowth? An experiment in rats

BACKGROUND

Nifedipine (NIF) may aggravate cyclosporin A (CsA)-induced gingival overgrowth because the potentiated gingival overgrowth has been observed in the patients treated with CsA and NIF. The purpose of this study was to evaluate whether NIF could aggravate the CsA-induced gingival overgrowth in a rat model.

METHODS

Ninety male Sprague-Dawley rats were divided into 6 groups: the first group received 8 mg/kg of CsA daily by gastric feeding for 6 weeks; the second and third groups received NIF daily at a dosage of 10 or 50 mg/kg; the fourth and fifth groups received CsA (8 mg/kg) and NIF (10 or 50 mg/kg); and the sixth group received solvents as a negative control. Gingival dimensions (including bucco-lingual depth, mesio-distal width, and vertical height) were assessed bi-weekly from impressed stone models of the mandibular incisal region. At the end of the experiment, the animals were sacrificed. Following histopathological procedures, serial horizontal sections were obtained at the base of the central incisal papilla. Two tissue levels were selected for histometric analysis. Level 1 was defined as the point where the lingual gingiva embraced the bucco-lingual midpoint of the roots and the level 2 as the point where the lingual gingiva at the enamel-dentinal junction approximated the bucco-proximal angle of the roots. The bucco-lingual depth and the mesio-distal width of the papilla were recorded on 5 consecutive sections at the 2 levels, respectively.

RESULTS

At the 6-week observations, the gingival dimensions (including the depth, width, and height) significantly increased after CsA therapy and the increasing treatment duration; however, only the mesio-distal width increased after NIF therapy. For NIF therapy alone, a positive linear relation was noted by increased NIF treatment dosages in all gingival dimensions at week 6. But, this relationship was not found in the combined therapies. By histometry, tissue dimensions increased following single drug therapy, either CsA or NIF, at both levels. In animals with the combined therapies, the tissue dimensions decreased if the animals received 10 mg NIF, while they rebounded to control levels with the 50 mg dosage. A dose-dependent positive pattern by NIF was noted in tissue dimensions, but the pattern did not occur in animals that received combined therapy.

CONCLUSIONS

The gingival dimensions increased after CsA or NIF therapy, although they were more prevalent with CsA. But the augmenting pattern in gingival morphology observed with CsA therapy decreased when the animals received additional NIF. Therefore, we question whether NIF is a critical factor in aggravating the CsA-induced gingival overgrowth.

Ameliorated effect of L-arginine supplementation on gingival morphology in cyclosporin-treated rats

BACKGROUND

The role of nitric oxide (NO) in the pathogenesis of cyclosporin (CsA)-induced gingival overgrowth is unknown. The purpose of the present study was to evaluate the effect of NO substrate (L-arginine) and blockade (N-nitro-L-arginine methylester-hydrochloride, L-NAME) on the gingival morphology in CsA-fed rats.

METHODS

Sixty CsA-fed (10 mg/kg/day) male Sprague-Dawley rats were assigned to 3 groups. Animals in 2 experimental groups received L-arginine (1% weight/weight) in rat chowder or L-NAME (50 mg/l) in drinking water, respectively, for 4 weeks. Rats in the control group were fed a normal diet and water. At week 0, 2, and 4, dental stone models were made from the mandibular anterior region and the gingival dimensions (width, depth, and height) were measured. The tail cuff blood pressure and the plasma nitrate level were also measured at week 4 to monitor the effects of L-arginine and L-NAME treatment.

RESULTS

No significant difference in the gingival dimensions was noticed at week 0; however, significant differences were observed at weeks 2 and 4, except the buccolingual depth at week 2. While the magnitude of gingival dimensions was large, moderate, and small in control, L-NAME, and L-arginine groups, respectively, we found significantly reduced gingival dimensions in both L-arginine supplement and L-NAME groups. Nevertheless, the reduced gingival overgrowth in the L-NAME treatment group was far less than that in the exogenous NO treatment group. Plasma NO2-/NO3- concentrations were also significantly different; i.e., from the highest to the lowest levels were the L-arginine, CsA control, and L-NAME group, respectively. A significantly increased mean and diastolic blood pressure was found in the L-NAME group compared to the L-arginine group.

CONCLUSIONS

Gingival morphology in CsA-fed rats was evaluated after NO substrate (L-arginine) and blockade (L-NAME) treatment for 4 weeks. Significantly decreased dimensions were noted in the L-arginine group compared to the CsA group at weeks 2 and 4. Although an inhibitory effect on the gingival morphology was also observed in the L-NAME group, another unknown mechanism might be involved. Within the limitations of the study, we suggest that NO may have an important role in the mechanism of CsA-induced gingival overgrowth.

Effects of cyclosporin A on the mandibular condylar cartilage in rats

Twenty, 5-week-old, male, Sprague-Dawley rats were divided into a control and a cyclosporin A (CSA) group for evaluating effects of the drug on condylar cartilage. Animals in the treatment group daily received CSA (15 mg/kg body wt) in mineral oil by gastric feeding over a 4-week observation interval. Control animals received mineral oil only. Five animals from each group were killed at weeks 2 and 4 of study. After histological processing, five tissue sections from the mid-region of the condyle were selected and examined. Three compositional zones (articular fibrous, proliferative, and hypertrophic) of the superior, posteriosuperior and posterior regions of the condylar cartilage were evaluated by light microscopy. At week 2, total condylar cartilage thickness was similar in the CSA and control groups, but the thickness of each zone was altered in CSA-treated animals, including a decrease of the fibrous and proliferative zones and an increase in hypertrophic zone compared to control (P<0.05). At week 4, CSA-treated animals exhibited overall decreased cartilage thickness, including decreased thickness of each zone compared to control (P<0.05). The results suggest that CSA has an inhibitory effect on the maturation of the mandibular condyle in rats.

Alterations of gingival morphology in nifedipine-fed rats

BACKGROUND

Gingival enlargement induced by nifedipine (NIF), a calcium antagonist, has been reported in human and animal studies. However, three-dimensional morphologic measurements of gingivae have never been used to describe this type of enlargement. We previously established an animal model of cyclosporin-induced gingival enlargement. The present study used morphologic measurements to examine whether or not NIF-induced gingival enlargement occurs in the animal model.

METHODS

Eighty male Sprague-Dawley rats were divided into four groups. Rats in each group received daily NIF, at a dosage of 0, 10, 30 or 50 mg/kg body weight, by gastric feeding for nine weeks. Gingival dimensions (including buccolingual and mesiodistal widths, and vertical height) were assessed from stone models obtained from the mandibular incisor regions every three weeks.

RESULTS

Over the course of the nine-week experiments, significant dimensional changes of the gingivae were observed according to two main factors: 1) the dose or, 2) the treatment duration. Gingival dimensions (including buccolingual and mesiodistal widths, and vertical height) significantly increased with the duration of NIF treatment. Dimensional alterations of gingivae were noted among the different dosage groups, but significant differences were mainly observed in those groups compared to the 50 mg/kg group.

CONCLUSIONS

The finding of increased gingival morphology in NIF-treated rats in this study shows that gingival enlargement can be induced by NIF in rats.

Analysis of diagnostic metabolites by capillary electrophoresis-mass spectrometry

We describe here a procedure by capillary electrophoresis-mass spectrometry (CE-MS) for the direct analysis of urine samples on diagnostic metabolites, which are present in patient urine with metabolic disorders. The method was demonstrated using urine samples spiked with diagnostic metabolites, including glutathione for gamma-glutamyl transpeptidase deficiency, pyroglutamate for generalized glutathione deficiency, adenylosuccinate for adenylosuccinase deficiency, omithine for gyrate atrophy, histidine for histidinemia, and homogentisic acid for alcaptonuria, at concentrations similar to those found in patients' urine. A coaxial sheath liquid flow was used for coupling CE and MS in electrospray ionization mode. Identification of the metabolites is based on their molecular weights and fragmentation patterns. The CE-MS method is highly specific and sensitive comparing to the previously reported method using migration time and UV absorption for identification. It should find broad application in clinical and pharmaceutical research and development.

Effects of cyclosporin A on alveolar bone: an experimental study in the rat

BACKGROUND

There have been several investigations on the role of cyclosporin A (CSA) in gingival hyperplasia in both animals and humans. However, less attention has been given to the drug's effect on alveolar bone. This study used light microscopy to histologically and histometrically evaluate the effects of CSA on alveolar bone in the rat.

METHODS

Sixty, 6-week-old Sprague-Dawley rats were separated into test and control groups. Animals in the test group received CSA in mineral oil (30 mg/kg body weight) daily by gastric feeding over the 6-week study. Control animals received only mineral oil. Ten animals from each group were sacrificed at weeks 2, 4, and 6. After histologic processing, the labial crest of the alveolar bone in the anterior mandible was evaluated by light microscopy.

RESULTS

A distinct pattern of increased osteoclasia and reduced bone formation was observed in the CSA-exposed animals compared to the controls. Increased osteoclasia was observed in periodontal sites and decreased bone formation was observed in symphyseal sites.

CONCLUSIONS

The results suggest that CSA has distinct effects on alveolar bone.

Free radicals are involved in methylmethacrylate-induced neurotoxicity in human primary neocortical cell cultures

Methylmethacrylate monomer (MMA), a highly volatile material, has been extensively used for the construction of complete or partial dental prostheses. While previous studies have indicated a variety of complications and untoward side-effects associated with its use, the possible neurotoxicity induced by this monomer has not been addressed. In this study, we have investigated the MMA-produced neuronal injury in human neuron-enriched primary culture. Embryonic brain tissue (8-10 weeks postconception) was used for the primary neuron-enriched culture. Phase-contrast microscopy was used to evaluate morphological changes of cultured neurons. Extracellular concentrations of lactate dehydrogenase (LDH) and nitrite was measured from the culture medium to assess the magnitude of neuronal damage and nitric oxide formation, respectively. Neocortical neurons exposed to the monomer (1/200, Vmonomer/Vglycerol) for two days resulted in a significant increase in the LDH level but monomer (1/20000, 1/2000, or 1/200; Vmonomer/Vglycerol) failed to increase the nitrite level. Morphologically, the neurons subjected to monomer treatment exhibited irregular shrunken cell bodies with dystrophic and/or fragmented neurities, or even cell lysis. Moreover, superoxide dismutase plus catalase or vitamin C pretreatment protected against monomer-induced neurotoxicity. Our results suggest that this neurotoxicity can not likely be attributed to the cytotoxic effects of nitric oxide but may be mediated through the toxicity of superoxide and other free radicals. This is the first time, to our knowledge, that neurotoxicity induced by MMA has been demonstrated in human cortical neurons.

Carious lesions in the heroin addicted patient. A case report

Heroin abuse is destroying the health of many individuals in our society. Much of the information that has appeared in the literature has concerned itself with the general health of addicts; the oral health status of these individuals has not been studied to the same extent. This report will present and discuss the management of a case involving the effects of long-term heroin abuse on the dentition.

Nifedipine-induced gingival overgrowth in rats: brief review and experimental study

The first case report of gingival overgrowth induced by nifedipine (NIF), a calcium-beta blocker, was in 1984. However, the association between gingival alterations and the drug therapy of sodium diphenyl hydantoinate was initially described in 1939. The purpose of the experimental study was to examine the effect of NIF on gingival morphology in an animal model. Forty-five male Sprague-Dawley rats were randomly divided into 3 groups. Animals in each group daily received NIF in dimethyl sulfoxide by gastric feeding at a dosage of 0 (control), 30, or 50 mg/kg body weight for 9 weeks. Gingival gross morphology was assessed tri-weekly from stone models obtained from the mandibular incisal region. Animals were sacrificed at the end of study and tissue blocks were processed for histopathologic and histometric evaluation. Histometric analysis was performed at 5 selected tissue levels. Macro- and microscopic significantly increased gingival dimensions were demonstrated in NIF-treated animals compared to control. Although a fibrovascular tissue was observed in the tooth-gingiva interface for both NIF-treated and control animals, it was thicker and appeared earlier in NIF-treated animals. The results of the present study suggest that gingival overgrowth can be induced by NIF in rats and that the gingival overgrowth appears dose dependent.

Gingival overgrowth and dental alveolar alterations: possible mechanisms of cyclosporin-induced tooth migration. An experimental study in the rat

The inter-incisal distance and dimension of the interdental papilla between the mandibular incisors were examined in cyclosporin A (CSA) fed rats over 6 weeks. Rats in the test group received CSA daily in mineral oil by gastric feeding (30 mg/kg body weight); the control group received mineral oil only. The inter-incisal distance and gingival dimensions, including bucco-lingual width and vertical height, were assessed biweekly from alginate impressed stone models. Animals were sacrificed at the end of the study and tissue sections were obtained from the anterior region of the mandible for histopathological evaluation. Both the inter-incisal distance and the dimension of the interdental papilla were significantly greater in CSA-exposed animals compared to control. The significant alteration appeared earlier in the papillary dimensions than that in the interdental distance. Particular histopathological alterations of the soft and hard tissues of the periodontium were observed in CSA-exposed animals. Within limitations of the study, we suggest that the CSA-induced gingival overgrowth may offer an active force contributing to observed tooth movement, however, remarkable alveolar remodeling should be considered as an undetermined factor for the movement.

Bone morphogenetic protein-2 for peri-implant bone regeneration and osseointegration

Recombinant human bone morphogenetic protein-2 (rhBMP-2) induced bone regeneration and osseointegration was evaluated in supraalveolar peri-implant defects in 5 beagle dogs. Alveolar bone was reduced 5 mm in height in mandibular premolar areas and the premolars were extracted. Three 10 mm titanium fixtures were placed 5 mm into each reduced alveolar crest, leaving 5 mm in a supraalveolar position. Alternate quadrants in consecutive animals received a surgical implant consisting of 2 ml rhBMP-2 (0.43 mg/ml) in a type I bovine collagen carrier, or the carrier alone (control). Fixtures and surgical implants were submerged under the gingival flaps. The healing interval was 16 weeks. Histometric and radiographic evaluations were made. Defect height averaged (+/- SD) 5.3 +/- 0.2 and 5.1 +/- 0.2 mm for rhBMP-2 and control defects, respectively (P > 0.05, n = 5, paired, t-test) Bone regeneration (height) averaged 4.2 +/- 1.0 and 0.5 +/- 0.3 mm for rhBMP-2 and control defects, respectively (P < 0.05). Bone regeneration (area) averaged 6.1 +/- 6.3 and 0.2 +/- 0.2 mm2 for rhBMP-2 and control defects, respectively (P > 0.05). Osseointegration within the confines of the defect averaged 19.1 +/- 10.1% and 8.2 +/- 4.6% for rhBMP-2 and control defects, respectively (P > 0.05). Osseointegration within regenerated bone averaged 29.1 +/- 9.8% and 65.3 +/- 15.3% for rhBMP-2 and control defects, respectively (P < 0.05). Osseointegration within the retained alveolar bone averaged 67.1 +/- 4.6% and 68.1 +/- 3.6% for rhBMP-2 and control defects, respectively (P > 0.05). The results suggest that there is a potential for rhBMP-2 induced bone regeneration and osseointegration in surgical peri-implant defects.