JOURNAL OF RESEARCH IN MEDICAL SCIENCES (JRMS)
Year:2002 | Volume:7 | Issue:3|Papers Count:18

Interoduction. Treatment of trumatized crown fractured teeth with open apex is a major problem in endodontic treatment. Long term stability of such teeth depends upon the maintainace of pulp vitality. The time period between the accident and the treatment affects the pulp vitality as well as the type of treatment and prognosis.The objective of this study was to provide a rough time table of pulpal inflammation and necrosis after the exposure of crow - fractured teeth to oral Environment.Methods. Fourty eight canine teeth in 12 young cats were used in this experiment. To make sure the teeth apecies were all open, they were checked by radiograph. The crown of all the teeth were cut 2mm from the CEJ and the pulps were left open to oral inviornment for periods of 1, 3, 7, 14, 28, 90 days. Animals were then sacrificed by vital perfusion fixation technique.Results. The mean depth of pulpal inflammation and necrosis for periods of 1, 3, 7, 14, 28 and 90 days were 1.98, 3.3, 2.39, 2.84, 3.92 and 8.57, respectively. There was no statistically significant difference between the time periods of 1, 7 and 14 days. Where as, time periods of 14 and 28 days showed significant difference. In 90 day time period, all the teeth showed total pulpal necrosis and was significantly different from all the other groups.Discussion. It appears that, trumatized open apex teeth exposed to oral Enviornment for less than 28 days could be well treated by apexogenesis. Considering the sufficient blood supply to open apex teeth in cases of deep inflammation and necrosis the teeth could be saved by partial pulpectomy. Only cases of total pulp necrosis should be treated by apexification technique.

Introduction. The effect of reformatory reduction on seal and retention of the cemented post with zinc phosphate cement considered in four different times.Methods. After tooth preparing, supply of molding post and cement, the reformatory reduction performed on samples except control group. The starting times are as follows: 1. Immediately after cementing; 2. Six minutes after cementing; 3. One hour after cementing; And 4. 24 hour after cementing. Thensamples are kept in normal saline, in 37c,moisture 100%. In order to close test qualificauon to normal condition of mouth, after reduction completion, the samples go under the termocyclic operation. Then dye penetration, sample incision and amount of leakage, considered by reflective microscope.Results. The dye penetration"s average in different groups has has meaningful difference. The group which has no meaningful difference with control group, is that on which reformatory reduction has performed 24 hour after post core cementing. The others have meaningful difference with control group. There is no meaningful difference between two consecutive groups on which reformatory reduction performed in different times.Discussion. We recommend cememted post-core after final setting of cement

Introduction. The purpose of this study was to compare shear bond strength of composite resins to etched dentin in both dry and wet dentin surface with active and inactive application of a single-bottle adhesive resin (Single Bond, 3M Dental products).Methods. Fourthy four intact human extracted molars and premolars teeth were selected. The facial surfaces of the teeth were grounded with diamond bur to expose dentin. Then specimens were divided into four groups of 11 numbers (9 Molars and 2 Premolars). All the samples were etched with Phosphoric Acid Gel 35% and then rinsed for 10 seconds. The following stages were carried out for each group: Group I (Active-Dry): After rinsing, air drying of dentin surface for 15 seconds, active priming of adhesive resin for 15 seconds, air drying for 5 seconds, the adhesive resin layer was light cured for 10 seconds. Group III (Inactive-Dry):After rinsing, air drying of dentin surface for 15 seconds, adhesive resin was applied and air dryied for 5 seconds, the adhesive layer was light cured for 10 seconds. Group III (Active-Wet):After rinsing, removal of excess water of dentin surface with a cotton roll, active priming of adhesive resin for 15 seconds and air drying for 5 seconds, the adhesive layer was light cured for 10 seconds. Group IV (Inactive-Wet):After rinsing, removal of excess water of dentin surface with a cotton roll, the adhesive resin was applied and air dryied for 5 seconds and then cured for 10 seconds. After adhesive resin application, composite resin (Z250, 3M Dental products) was applied on prepared surface with cylindrical molds (with internal diameter of 2.8mm, & height of 5mm) and light-cured for 100 seconds (5x20s). The samples were then thermocycled. They were located in 6±3c water .temperature for 10 seconds and then 15 seconds in inviromental temperature, 10s in 55±3c water temperature and then were located at room temperature for 15s. This test was repeated for 100s. All of the specimens were then mounted in acrylic molds. After thermocycling and mounting of the samples, shear forces were applied on the restorations by universal test machine (Dartec) with cross head speed of 5mm/min. The maximum shear bond strength (MPa) was calculated. Results. The mean shear bond strengths and standard deviations for group I (active-dry),II (nonactive - dry), III (active-wet) and IV (nonactive-wet) were 11.55±8.59, 11.02±4.1, 23.38±8.09 and 26.34±6.97MPa respectively.Discussion. Results indicated that there was a statistically significant difference between groups I,II and groups III,IV .In the other hand, groups III and IV have shown a good and sufficient mean shear bond strength which means the wettness of dentin surface, has a significant role on enhancement of shear bond strength of Single - Bond to etched dentin and the application of active or inactive priming dose not have a significant role on enhancement of the bond strength and can be deleted as an aditional stage. 93% of the total failure modes were adhesive, 4.5% were mixed (dentin-adhesive) and 2.5% were mixed (composite-adhesive).

Introduction. Because of advancements in dental restorative techniques and introduction of new materials, the patients demand for suitable restorations has been increased. Composite resin restorations are suitable restorations, because of conservative preparation and acceptable appearance. One of the basic stages of direct composite restoration is enamel acid etching to provide retention of restoration and eliminating microleakage.Methods. Different studies, have recommended use of phosphoric acid (30-40%) for 15s and rinsing time of 15-20s. It seems that this method leads to acceptable enamel bond strength. In this study, the enamel shear bond strength of composite resins with use of Kimia, Pish-Ro and 3M acids was investigated. Also, the pattern of enamel etching by these acids was investigated under SEM observation. After collection of 33 intact canines and premolars, the buccal surfaces were grinded. The teeth were divided into 3 groups and then etched with different acids for 20s, then rinsed for 15s. 2 Coats of Single Bond adhesive resin were applied on the surface and cured for 10s. Z100 composite resin was applied on the surface with cylindrical molds and cured for 100s (5x20s). After thermocycling and mounting of samples, shear forces were applied on the restoration with Dartek instron and the data were analyzed by 1-way variance analysis, Kruskal-wallis test and Duncan"s test. For SEM observation 10 human maxillary central incisors were selected with no lesion. After cleaning and storage in 0.2% thymol, the teeth were divided into 2 groups. The labial surface of the teeth were polished and divided into two mesial and distal portins. Mesial portion of each specimen was treated with 3M acid and the distal portion was treated with Kimia acid. The first group was etched for 45s and the second group for 20s. After rinsing for 20s and drying for 20s, the etching patterns were observed under SEM observation.Results. Mean shear bond strength of Kimia group was 24.57 MPa, 35.17MP a for Pish-Ro group and 36.93 MPa for 3M group. The difference of mean shear bond strength was not significant (P>0.05) but the difference of failure mode was significant (P<0.05, X2=16.3). It seems that the applied adhesive resin system is more important than type of phosphoric acid.Discussion. The main enamel etching pattern was type II in the middle and inciasl portions and type III in the cervial areas. Also, some evident morphologic differences were observed. First, the etching patterns gained by standard acid were more even in comparison with Kimia acid. Another difference was the recognition of more deposits on the surfaces etched with Kimai acid. lastly, Image Analyzer showed higher percent of area fraction surfaces created with standard acid.

Introduction. The aim of this study was to assess the sealing ability of three sealers (AH-26,Roth-801, Pure ZOE paste) using bacterial penetration method in static salivary system in the presence or absence of smear layer.Methods. The canals in 188 human extracted teeth were prepared and in half of the samples the smear layer was removed using EOTA- Naclo. Then, the samples were divided randomly and each experimental group was obturated with single cone gutta percha and of the mentioned sealers. Then the teeth were set up on vials which contained sterilled TSB cultural media. For 90 days the samples were exposed to artificial saliva bacterial suspension and the turbidity of the cultural media was checked twice a day.Results. The longest mean period of turbidity was seen in AH-26 smear layer absent group (59.21 days) and the shortest mean period of turbidity was seen in pure ZOE paste smear layer present group (18.35 days).Discussion. The results of this study shows that removal of smear layer enhances the sealing sealers and AH-26 has the best sealing ability amongst the three sealers considered in this experiment.

Introduction. Pain and the need for controlling it is a determinant factor in dental treatment procedures. One of the most common methods of local anesthesia in mandibular area is infra alveolar nerve block which has failure rate of 5% to 15%. The purpose of this study was to locate the optimal needle entrance point in order to achieve a fast, deep and durable anesthesia with minimal anesthetic consumption.Methods. This cross-sectional study has been performed on 38 cadavers of Iranian males with approximate age of more than 17 years. old. They had normal occlusion and at least 2 molars in each quadrant of the mandible if a sample was edentulous in one quadrant of the mandible or in the opposite jaw; or when a severe tilt in mandi bular dentition was present and in the case of mandibular or condylar fracture, the sample was excluded from the study. Distance between lingual and occlusal plane was measured by a device with two parallel plates. The precision of the measurment was 1mm. Data was analysed by the use of SPSS software.Results. On the right side, the average distance between lingual and occlusal plane was 2.4±4.4 (Mean±SD) and on the left side, was 2:r.4.4 which there was no significant difference between right and left sides (P value=0.9).Discussion. In this study the human body is used and the best point for entrance of the needle for inferior alveolar nerve block technique is located at 8mm above the occlusal plane. At this point the anesthetic solution will be evacuated in the nearest position to the inferior alveolar never.

Introduction. The treatment of furcation involvement is difficult due to the anatomic problems that interfere with the clinician"s accessibility in treating the area and the patient"s ability in maintanining adequate plaque control afterwards. The goal of traditional methods of treatment is to arrest the progression of the bone loss. the ratio of success with these methods has been poor, except for grade I involvements. Guided tissue regeneration has improved the long-term prognosis of many deep grade II lesions but has not always shown consistent predictability. The purpose of this study was to evaluate the clinical effectiveness of a resin modified glass ionomer as a barrier in the treatment of class 11furcation defect in mandibular molars.Methods. Twenty six (13 eperimental and 13 control) defects were treated in 13 patients that presenting matched pair defects. The following clinical measurments were taken at baseline (after phase I) and 6 month after surgery: plaque index bleeding index, gingival recession, probing pocket depth, probing attachment level. Healing was uneventhful in all cases and barrier remained in place.Results. No statistically singificant difference was found between the experiment group (use the resin modified glass ionomer) and control group (use the flap surgery alone) respectively. Plaque index reduction (1.38±0.65 VS 1.24±0.45) bleeding index reduction (0.6±0.48 VS 0.69±0.48) (Mean±SD) and gingival recession (0.3±0.48 VS 0.27±0.57) and reduction probing pocket depth (2.38±0.74 VS 2.92±0.38) were noted. but statistically significant difference in gain of probing attachment level (3.07±0.67 VS 1.96±1.07) were found.Discussion. The study offers another treatment plan in the treatment of futcation defect molars. More study may be necessary to evaluate efficacy and adverse effects of resin modified glass ionomer.

Introdaction. Microleakage has been recognized as a major clinical problem with direct filled dental restorations.The purpose of this study was to investigate and to compare the microleakage of four direct filled tooth-coloured materials, evaluation the effects of polishing time and thermocycling on the microleakage of these materials.Methods. Wedge-shaped class V cavities were prepared on buccal and lingual surfaces of 96 intact extracted human molar teeth. The teeth were randomly divided into three treatment groups and four subgroups. The cavities of each subgroup were filled using one of these materials: a conventional glass ionomer; a resin modified glass ionomer; a composite resin and a compomer. Polishing in the teeth of group 1 was done immediately after placement of restorations and in group 2 one week later. In group 3 delayed polishing and thermocycling (X100) was done. All of the teeth were stored in distilled water for one week and then stained with dye, sectioned, and scored for microleakage on occlusal and cervical edges. Results were statistically analyzed by Kruskal wallis and Mann whitney tests.Results. There was a statistically difference between the microleakage scores of four materials (P<0.001). Immediately polished glass ionomer and compomer groups have significantly more microleakage than delayed polished groups (P<0.001). Thermocycting could infulence the microleakage of composite on cervical edges (P<0.05).Discussion. The precense of differences between the nature of materials and also the surface treatment such as primer or etchant application could influence the microleakage. The prescence of differences in reaction rate between the materials and the time that they reach to their adequate mechanical strength and adhesive bond strength lead to presence of differences between the effect of polishing time on the microleakage scores of materials.

Introduction. One of the most common repairs in removable prostheses is, substitution debonded teeth in their places. In the other hand, with the incrased use of implants & the commensurate increase in force applied to prosthetic components, it is probable that tooth debonding will become an even greater clinical problem. Therefore in this study we are trying to select the strongest bond strength of Iranian denture teeth with respect to lvoclar denture teeth (Approved and recommended by ADA).Methods. In this study the upper anterior set of three Iranian denture teeth (called Berelian, Marjan and Supernevoclar) and lvoclar denture teeth were used. of each type of denture teeth, 21 specimens was selected and the denture teeth glaze was removed in each specimen. Then the laboratory procedures (removal of wax & resin packing) according to British Standard 3990 (BS 3990) or ISO 3336 was done. Each specimen was tested by an Instron machine. The tensile test used with the cross-head speed of 5mm/min until fracture occured.Results. The mean bond strength in Berelian teeth uppermost, afterward Marjan, Ivoclar and Super nevoclared in second, third and fourh rank respectively. But statistical analysis showed no significanrt difference among the mean bond strength in four groups of denture teeth. The percentage of cohesive fracture (sum of acrylic farcture and dental fracture) in Berelian specimens was uppermost, afterward Supernevoclar and Marjan were placed in second, third & fourth rank respectively. But statistical analysis showed no significant difference among the percentage of cohesive fracture in different groups of denture teeth.Discussion. The bond strength and the percentage of cohesive fracture of Iranian denture teeth is the same & competitive to lvoclar denture teeth (approved and recommended by ADA).

Introduction. Gingivitis is the most common periodontal disease in children and adolescents. Inspite of changing concepts on the etiology and caltural history of periodontal disease over the last few decades, plaque control by self care is still regarded as an essential step in the prevention and treatment of gingivitis. Since most individuals, especially children and adolescent seem to have difficulty in achiving perfect plaque control by mechanical means, investigations has been directed towards the development of safe and effective antiplaque dentifrices. Herbal components have been successfully used in dentistry as tooth cleaning and antiplaque agents. The objective of present study is to evaluate the clinical effects of a dentifrice containing the extracts of sages chiory and siwak on gingivitis and plaque control amongst a group of adolescents in Mashhad.Methods. A double-blind clinical trial was designed to evaluate the effects of a dentifrice containing Sage, Chicory and Siwak extracts on the control of plaque and gingival inflammation in 12-13 years old boys. Sixty students were divided into two groups. One group used test dentifrice and the other used placebo dentifrice daily. At the begining of the trial each subject was scored for plaque and gingival indices (PI and GI) clinical evaluation were examined after 28 days.Results. Analyzing the baseline data showed no significant defference between the PI and GI indices in the test and control groups. But at the end of the trial, there was highly significant difference (P<0.001) between the mean value of GI in two groups. The effect of test dentifrice on the reduction of GI versus the palcebo dentifrice was 54.21%. Also at the end of the trial there were significant difference (P<0.004) between the mean value of PI in two groups. The effect of test dentifrice on the reduction of PI compare to the placebo dentifrice was 2.3%. Discussion. It was concluded that the herbal dentifrice was effective in the control of plaque and gingivitis and it have not been associated with side effects.

Introduction. Enamel acid etching prior to repair dental caries and fractures with composites has been quite satisfactory and economic, however, etching on deciduous dentition has shown less effective due to its resistance to acids. The purpose of this study was to evaluate composite bond strength on decidious teeth treated with laser instead of being acid etched.Methods. Forty four deciduous molars without any restoration or buccal decay were chased and randomly divided in the four groups of 10. Four other teeth were prepared for SEM observation. Group 1: samples were treated with Nd: YA Glaser (20 pps, 1.6 w). Group 2: samples, treated with Nd: YA Glaser (10 pps, 0.8 w). Group 3: samples acid etched with 37% phosphoric acid. Group 4: samples in this group were taken as control with no treatment on enamel. Shear bond strength of the composite and teeth in all 4 groups were then measured with universal tast machine (Dartec).Data were analysed statistically using ANOVA test.Results. The least mean amount of bond strength was related to group 4 (control), which was significantly different from other groups (P<0.05). The most mean amount was related to group 3 (acid etched) with statistically significant difference from other groups (P<0.05). Among the samples treated with laser, group 1 has greater amount of mean strength comparing to group 2, however this difference was not significant (P>0.05).Discussion. In order to obtain optimum bond strength for composite restorations, enamel surface should be prepared. Use of Nd: YAG laser for enamel etching under the condition of our study is not recommended on deciduous dentition.

Introduction. Compoglass is a trade mark of dental compomers and because of its partially resinus structure, surface conditioning of dental surfaces is needed for a better bonding process. In this study, the effect of enamel and dentin conditioning procedure on shear bond strength (SBS) of compoglass to tooth surfaces was studied.Methods. four groups each one including 11 sound premolars were chosen and their surfaces were prepared as following groups: group1, unconitioned dentin; group 2, dentin conditioning with phosphoric acid 35%; group 3, dentin conditioning with polyacrylic acid 20% group 4, unconditioning enamel; group 5, enamel conditioning with phosphoric acid 35%; and group 6, enamel conditioning with polyacrylic acid 20%. Compoglass was bonded to prepared surfaces and after fixation of the samples in acrylic molds, all samples were tested under shear force of instron testing machine at a rate of 1 mm/min speed.Results. The mean SBS obtained in these 6 groups were 6.207, 8.057, 10.146, 25.939 and 11.827 mpa. the mode of fracture also studied using a streomicroscope. Statistical analysis of the results showed that the maximum SBS obtained in group 5 and the lowest SBS about 6.207 mpa obtained in group 1. Despite increase in SBS group 2 and 3, there was no statistical differncies between group 1, 2 and 3.Discussion. Based on results of this study, conditioning of enamel and dentin surface due to improve SBS is recommeneded.

In this study, knowledge, attitude and practice about mercury hygiene of dentist who have private offices in Isfahan were evaluated.This cross-sectional study was carried out in 2001-2002. One hundred and sixteen of dentists were selected by random sampling. Data were collected using a standard questionnaire. T-student test, Chi-square test, Fisher"s exact test and Spearman correlation test have been used to analyse data. It was shown that dentists knowledge about mercury hygiene was not acceptable. However the mean of their attitude score was more than scale mean and most of them had a positive attitude toward improvement of mercury hygiene in their offices. According to the results, dent ist"s practice, in this regard proved weak. There was no significant correlation between knowledge and practice and between attitude and practice (P>0.05).In order to improve dentists" knowledge, training them is supposed. Because of no significant correlation between their knowledge and practice, surveillance seems necessary.

Remained teeth and other lesions such as cysts, abcesses and tumors is one of the important problems in edentulous patients.In a cross-sectional study, 330 edentulous patients were evaluated radiographically. The radiographic evaluation of patients revealed the presence of 86 residual roots in 58 radiographs. 17.58% of patients had residual roots & 5.8% of patients had Impacted teeth. 58.1% of residual roots and 45% of impacted teeth were in the maxilla and others were in mandible. Maximum Percentage of residual roots (58.1%) and impacted teeth (70%) were found in molar region. In this study revealed 23.3% of examined patients had remaining dental fragments. From these patients, 5.76% had impacted teeth and 17.58% had residual roots, and maximum percentage of rooth fragments (58.1%) were found in molar region. In similar study by spyropoulus, maximum percentage of root fragments (45.6%) reported in molar region and maximum percentage of impacted teeth were found in molar and canine region (41.2% in molar and 41.2 in canine region). In this study, 58.1% of root fragments and 45% of impacted teeth were found in the maxilla but in spyropoulos" report, 71.9% of root fragments and 94.1% of impacted teeth were found in the maxilla.

In various studies it has been shown that major part of effective factors in root canal therapy failure is error during treatment. for example, in washington study nearly 76% of treatment failure factors are related to error during treatment. Considering that most of the errors are preventable, this study took palce for evaluating the errors during root canal therapy by students of Isfahan dental school and presenting suitable preventive strategies in order to increase the treatment success.In this study 1260 radiography of root canal treated teeth by students of semister 11 and 12 in years of 1999-7 were studied, and errors of each were diagnosed and registered in a checklist, at least with statistical analysis of collected informations, these results were obtained: In 1260 ispected cases,2752 errors were seen, that in average every tooth has 2.2 errors. Vertical gap with 430 cases was maximum and preparated but unfilled canal and middle root perforation with one case were seen rarely. Average error in each case in upper arch was 2.14 and in lower arch was 2.22 (P=0.35).Cosidering that incomplete obturation (include vertical gap and inadequate obturation) is the major treatment error in this study and taking in view that incomplete obturation in many studies such as Washington study is the major couse of treatment failure, so with regarding the correct treatment principle, should be prevented as far as possible.