An evaluation of antimicrobial potential of irreversible hydrocolloid impression material incorporated with chitosan.

AIM: To evaluate the antimicrobial potential of irreversible hydrocolloid impression material manipulated using chitosan impregnated solution at various time intervals. SETTING AND DESIGN: Evaluative invivo study design. MATERIALS AND METHODS: Maxillary impressions made for 20 dentulous volunteers using irreversible hydrocolloid impression material manipulated using distilled water as control and using 1% chitosan impregnated solution as test group using stock metal trays with one-week interval. Bacterial samples were collected using dry sterile cotton swab in the mid-palatal region at the time intervals of 0, 10, 20 minutes. Bacterial swabs were inoculated on nutrient agar media and incubated at 37° C for 24 hours. Bacterial colonies were counted with the aid of colony counter. STATISTICAL ANALYSIS USED: The resultant data was subjected to statistical analysis using repeated measures ANOVA and independent t test. RESULTS: Adding water soluble chitosan to irreversible hydrocolloid impression material resulted in superior antimicrobial activity. With the passage of time there was a significant decrease in the microbial colony count upto 10min (p=0.016). However, the rate of decrease of microbial colony count was statistically insignificant between the samples collected at 10 and 20 min. CONCLUSION: Incorporation of water soluble chitosan to irreversible hydrocolloid impression material showed significant antimicrobial activity in 10 minutes.

Evaluation of the effect of silicone residue after different surface treatments on shear bond strength of glass ionomer cement to the dentin surface.

AIM: Use of silicone fit-checking material during cementation of fixed restoration has shown to leave residual silicone film after peeling off of fit checker (FC). This residual film reduced bond strength of cement to the inner surface of restoration. Silicone residue effect on tooth surface needs to be studied. The aim of this study was to evaluate the effect of residual silicone film on shear bond strength (SBS) of glass ionomer cement (GIC) to dentin surface and the efficacy of different surface treatments (STs) on dentin in the removal of silicone residue. MATERIALS AND METHODS: Fifty freshly extracted human molars were individually mounted on acrylic blocks and occlusal surfaces were ground flat until dentine surface was exposed. Specimens were divided into five groups as follows: Group I: without application of FC (n = 10) as control group; Group II: without any ST after peeling off FC (n = 10); Group III: ST using wet pumice after peeling off FC (n = 10); Group IV: ST with 37% phosphoric acid after peeling off FC (n = 10); and Group V: ST with 10% polyacrylic acid after peeling off FC (n = 10). GIC was placed on the dentinal surface using polyvinyl mold and subjected to SBS test using universal testing machine. The debonded specimens were observed under stereomicroscope for the mode of failure. Selected debonded dentinal surfaces from each group were examined under scanning electron microscope. One-way analysis of variance and Tukey's test. RESULTS: Group II (1.083 MPa) showed significantly lower SBS. Among the STs, Group III (2.047 MPa) was comparable to the control group whereas Group IV (1.376 MPa) and Group V (1.63 MPa) were significantly lower. There was no significant association between failures and groups at P = 0.257. CONCLUSION: The residue of silicone was demonstrable on dentin surface after peeling off FC and caused a significant reduction in SBS between GIC and dentin. ST with wet pumice is found to be beneficial in removing silicone residue and improving SBS, followed by phosphoric acid and polyacrylic acid.

A study of change in occlusal contacts and force dynamics after fixed prosthetic treatment and after equilibration - Using Tekscan III.

AIM: A study has been undertaken to evaluate the changes in occlusal force dynamics after conventional prosthetic rehabilitation. MATERIALS AND METHODS: In Phase I, the preprosthetic phase, force distribution of 50% ± 10% on either sides of arch in maximum intercuspation and disclusion time (DT) <1 s during mandibular excursions was attained in all patients using Tekscan before starting prosthetic treatment. Conventional procedures to replace missing tooth by fixed dental prosthesis were carried out. Occlusal corrections were performed using articulating paper to the satisfaction of operator and patient. In Phase II, postprosthetic phase, 1 week after cementation of the fixed partial dentures, the occlusal force dynamics were rerecorded and evaluated using Tekscan. Any corrections required were done to restore the equilibrium. Occlusal perception of patient before and after equilibration was recorded by means of a standard questionnaire both in pre- and postprosthetic phase. Twenty patients requiring replacement of a single posterior missing tooth were selected. The obtained values were statistically analyzed using Student's t-test. RESULTS: Subsequent to rehabilitation, the right-left balance of occlusal load was lost and DT was significantly increased. However, the subjective evaluation revealed no significant decline in occlusal comfort. CONCLUSION: Null hypothesis was rejected. Operator's assessment of articulating paper marks and patient's occlusal perception is not reliable in restoring occlusal equilibrium.

Correlation of Condylar Guidance Determined by Panoramic Radiographs to One Determined by Conventional Methods.

BACKGROUND: To evaluate the feasibility of using panoramic radiographs as an alternative to an interocclusal recording method for determining the condylar guidance in dentate and edentulous conditions. MATERIALS AND METHODS: 20 dentulous individuals with an age range of 20-30 years and 20 edentulous patients of 40-65 years were selected. An interocclusal bite registration was done in protrusive position for all the subjects. Orthopantomographs were made for all patients in open mouth position. Hanau articulator was modified to record the angulations to the accuracy of 1°. Tracing of glenoid fossa on radiograph was done to measure the condylar guidance angles. Readings were recorded and analyzed by Freidman's test and t-test. RESULTS: Condylar guidance values obtained by the interocclusal method and radiographic method in dentate individuals on the right side and left side 40.55°, and 37.1°, and 40.15°, and 34.75°, respectively. In the edentulous individuals, the values on the right side and left side was 36.7° and 36.1° and 35.95° and 33.6,° respectively. The difference was statistically significant (P = < 0.001) in dentate group and was not statistically significant (P = 0.6493) in edentulous group. CONCLUSION: Panoramic radiograph can be used as an alternative to interocclusal technique only in edentulous patients. Further studies comparing panoramic radiograph to jaw tracking devices would substantiate the results of this study.

Immune response to an indigenously developed r-hepatitis B vaccine in mixed population: study of an accelerated vaccination schedule.

AIM: To establish the safety and efficacy of an indigenously developed r-hepatitis B vaccine using an accelerated schedule and to highlight the social awareness and commitment in preventing the spreading of hepatitis B virus infection. METHODS: The study was a multicentric, double blind, randomized (3:1) study using three doses of vaccine immunization schedule (20 mug for those above 10 years old and 10 mug for those below 10 years old) on d 0, 30 and 60. One hundred and sixty-six subjects were enrolled (87 males and 76 females aged 5-35 years). The main outcome measure was assessment of immunogenicity and safety. RESULTS: A 100% seroconversion response was observed on the 30(th) d after the 1(st) injection in both the experimental groups. The sero-protection data reported a 41.2-65.6% response on the 30(th) d after the 1(st) injection and reached 100% on the 60(th) d. Descriptive statistical analysis showed a geometric mean titer value of 13.77 mIU/mL in the test (BEVAC) group and 10.95 mIU/mL in the commercial control (ENGERIX-B) group on the 30(th) d after the 1(st) injection. The response on the 60(th) d showed a geometric mean titre value (GMT) of 519.84 mIU/mL in the BEVAC group and 475.46 mIU/mL in the ENGERIX-B group. On the 90(th) d, the antibody titer response was observed to be 2627.58 mIU/mL in the BEVAC group and 2272.72 mIU/mL in the ENGERIX-B group. Two subjects in each group experienced pains at injection site after the first vaccination. A total of six subjects in both groups experienced a solicited adverse reaction, which included pains, swelling and redness at the injection site, three subjects in the group-B had a pain at the injection site after the third dose. No other serious adverse events occurred and no dose-related local or general symptoms were observed during the study. CONCLUSION: The vaccine is safe, efficacious and immunogenic in comparison with the well documented ENGERIX-B.

Intensive care in rabies therapy. Clinical observations.

Seven patients in India with dog-bite rabies were treated by intensive therapy. Hypoxia was prevented by intermittent positive-pressure ventilation facilitated by muscle relaxants and sedatives. Other measures, included maintenance of nutrition, correction of fluid/electrolyte and acid/base balances, antiviral agents, immunological stimulation, and intensive nursing care by immunised volunteer staff. The patients survived for from 1 to 17 days after the onset of clinical disease. When survival was prolonged (i.e., more than 2-4 days) by intensive care, the disease had diverse and serious effects, including fluctuations in temperature and blood-pressure, cardiac arrhythmia, and diabetes insipidus. Although none of the patients survived, advances in the use of this technique raised hopes that it may eventually be possible to save some patients.