فهرست مطالب safoora sahebi

Statement of the Problem: 

Although various kinds of research have been conducted to compare the physical and chemical properties of dentin and enamel in animal and human samples, proving the ability of animal dentin material as a good substitute for human specimens is always a challenge for experimental studies.

The aim of the present study is to investigate whether the changes in the dentin microhardness of animal samples are similar to those of human samples or not.

In this in vitro study, sixty single-rooted human, bovine, and ovine teeth (n=20 in each group) were decoronated at CEJ. The remaining roots were embedded in acrylic resin and a cross-section cut was made in the middle of the samples in order to achieve dentin disks. All of the 120 samples were randomly assigned to three control (n=20 for each group) and three experimental groups (n=20 for each group). In the experimental groups, calcium hydroxide with a creamy consistency was prepared and the disks were embedded in dishes containing calcium hydroxide. Control groups were embedded in physiological saline. The samples were incubated for seven days at the 37oC and Vickers microhardness test was performed immediately. The average of three yielded values was considered as the final value of microhardness. Data were analyzed using two-way ANOVA, one-way ANOVA, and Tukey’s post hoc tests.

In the control group, the human samples showed the highest microhardness value, while the bovine teeth had the lowest microhardness value (p< 0.001). In the calcium hydroxide group, the human samples showed the highest microhardness value in comparison to bovine and ovine to teeth. However, no significant difference was observed between the bovine and ovine samples in microhardness value.

Based on our research, substituting bovine and ovine samples with human samples in experimental studies is not recommended. Nevertheless, more studies are needed in this regard.

Statement of the Problem:

 Developmental anomalies such as dilacerations can affect the eruption pattern of permanent anterior teeth. They are characterized by a curvature in the crown and roots of the teeth relative to their normal axis. This anomaly can cause some complexities in routine dental treatments such as root canal treatment, orthodontics, and surgery.

The purpose of this study was to assess the prevalence of dilaceration in maxillary and mandibular anterior and canine teeth in Shiraz, Iran using cone-beam computed tomography (CBCT).

In this retrospective study, a total of 1537 encompassed 400 CBCT images collected from 4 private radiology clinics in Shiraz were assessed. Each tooth was radiographically examined in order to diagnose root dilacerations considering their location (apical, middle, coronal), position in the jaw (maxillary or mandibular), direction (mesial, distal buccal and palatal/lingual), and severity of dilaceration (mild, moderate, and severe). The obtained data were analyzed by Chi-square statistical test and Fisher’s exact test. 

In this study, out of 1537 studied teeth, 5.98% had dilaceration. The maxillary and mandibular canine teeth (9.8% and 9.7%, respectively) were significantly the most common teeth involved in this anomaly (p< 0.001). The distal direction with mild severity in the apical third of the root was also the most common result obtained from this study (p<0.001). In addition, there was no statistically significant relationship between gender and type of jaw regarding the prevalence of dilaceration in the studied dental groups (p=0.670 and p=0.231, respectively).

In the current research, it was demonstrated through CBCT records that the prevalence of dilaceration in maxillary and mandibular anterior and canine teeth is relatively uncommon. The most prevalent dilaceration was found to be distal direction with mild severity in the apical third of the root.

 The goal of this paper was to determine the impact of calcium hydroxide (CH) and nano-calcium hydroxide (NCH) on the push-out bond strength of an epoxy resin-based sealer. 

 A total of 48 mandibular premolars were decoronated in vitro and instrumented by a ProTaper rotary system up to F4. The specimens then were randomly allocated into 3 groups (n=16). The two intervention groups were treated with either CH or NCH and one control group which did not receive any intracanal medicament. After one week of medicament placement, the specimens were irrigated by 10 mL 17% EDTA, followed by 10 mL 2.5% NaOCl and an ultimate flushing by 5 mL sterile saline. The samples were obturated using AH-Plus Jet sealer and gutta-percha by lateral condensation technique. Push-out test was done by a universal test machine to evaluate the bond strength among the sealer and the root canal dentin. Repeated measurement analysis followed by Tukey’s HSD and Bonferroni post-hoc tests were used for data analysis. 

 The control group showed a higher push-out bond strength in comparison to the specimens in the CH and NCH groups (P<0.05). In spite of the greater push-out bond strength of the samples treated with NCH in comparison to those in CH group, no statistically notable difference was found among them (P>0.05). Additionally, irrespective of the kind of medicament, the bonding at the apical level of the root canal was stronger compared to the coronal third (P<0.001). 

 According to the present in vitro study, application of CH and NCH resulted in a significant reduction of the bond strength between the epoxy resin-based sealer and dentinal walls. Although, application of these medicaments resulted in reduction of bonding of epoxy resin-based sealers root canal dentin significantly.

Statement of the Problem: 

One of the annoying problems related to almost all root canal preparation systems, which may cause flare-ups and impairment in the healing process is the extrusion of intracanal debris.

This study was conducted to evaluate the amount of apically-extruded debris during root canal preparation using Medin (MEDIN Co., Czech Republic) rotary system compared with two common rotary systems, including Protaper (Dentsply Maillefer., Switzerland) and RaCe (FKG Dentaire, Switzerland).

Sixty mandibular premolars with single canal were randomly assigned to three groups (n=20). The root canals were prepared with Medin, Protaper and RaCe rotary instruments based on their manufacturers’ instructions. The debris were collected into pre-weighted Eppendorf tubes. The weight of the extruded debris was calculated by subtracting the pretreatment weight of the vials. Data were analyzed using the Kruskal-Wallis test at a 5% significance level.

Medin instrument caused significantly less debris extrusion in comparison with Protaper and Race (p < 0.05). The differences between the Protaper and Race rotary systems were not statistically significant (p = 0.752).

Within the limitations of this in vitro study, Medin rotary system produced less apical extrusion than Protaper and Race.

Statement of the Problem: 

Tooth color changes followed by treatment with bioceramic materials is always a matter of concern. In this article ,NFC as a new ceramic base material assessed for its ability to change the color of teeth.

The aim of the present in vitro study was to compare tooth discoloration that occurs in human teeth filled with ProRoot WMTA (DENTSPLY Tulsa Dental Specialties, Tulsa, OK) or NFC over the course of 3 months.

Thirty human intact premolars obtained and the root of all teeth was removed by horizontally cutting them about 2 mm below the cementoenamel junction, the pulp tissue was removed afterwards using a barbed broach (Mani, Tokyo, Japan).The teeth were randomly divided to 3 groups (n= 10 teeth per group);control (no material), ProRootWMTA and NFC. The experimental materials were condensed into the crowns and the tooth end sealed with light-cure glass ionomer cement (GC Corporation, Tokyo, Japan).Color was assessed at TBL: baseline (after preparation of the cavities but before placement of the materials), TPO: immediately after placement of the filling material and provisional restoration, T4: after 4 weeks of storage, and T12: after 12 weeks (3 months) of storage.

Discoloration was evident in all teeth, immediately (TPO) after applying MTA and NFC. The highest ΔΕ was noted in WMTA at 3 months, followed by NFC, but there was no significant difference between thediscolorations induced by these two materials.

There was a similar level of clinically observable tooth discoloration detected using either WMTA or NFC.

 Preventing recontamination of the obturated root canal is important for successful root canal treatment (RCT). The main purpose of this study was assessing the histological health of periradicular tissue in obturated root canals with or without coronal seal between two and six months.

Sixty roots from five dogs with vital pulps were randomly assigned to one of the following five groups (n=12): Group 1, RCT and six months oral exposure; Group 2, RCT and immediate amalgam restoration; Group 3, RCT and amalgam restoration after two months exposure to the oral cavity; Group 4, RCT and amalgam restoration after four months exposure to the oral cavity; Group 5, RCT with two months exposure to oral cavity. The teeth were prepared and filled with gutta-percha and sealer using lateral condensation technique. Two intact root canals of each animal were regarded as the negative control group (n=10), and the two root canals exposed to the oral cavity constituted the positive one (n=10). After six months the animals were euthanized. The upper and lower jaws were removed and submitted for histological processing. Longitudinal sections were obtained from each root. After staining the sections, periradicular regions were examined histologically under light microscope. The Kruskal-Wallis and Mann-Whitney tests was used to analyze the data (P<0.05). 

 The results showed a significant difference between all groups (P<0.05). The negative control group was free of any inflammation. Two-by-two comparison revealed that the positive control group, Group 1 and Group 4 displayed the most intense inflammation. Groups 2, 3 and 5 showed similar results without developing any significant inflammation. 

Based upon the findings of this animal study, it can be recommended that the obturated root canals which are exposed to oral cavity for around four months or more should be retreated before crown restoration.

The goal of apical surgery is to eliminate the root apex, apical lesions and promote tissue repair. In apical surgery, the root is resected at an angle of 45, 60 or 90 degree. In many cases, it is not possible to resect the root at 90-degree bevel and prepare a root-end cavity with 4-mm depth. The aim of this study was to evaluate the simultaneous effect of apical resection angle and depth of the retrograde filling with mineral trioxide aggregate (MTA) on apical microleakage. Methods and Materials: Root ends were resected at 45 degree, 60 degree and 90 degree bevels in 110 extracted human single root permanent teeth. For each apical surgery, root-end cavities were filled with MTA to depths of 2 mm, 3 mm and 4 mm. Root end-filled teeth were mounted in fluid filtration device. The evaluation was conducted after 24-h, 1 week, 1 month, 2 months and 3 months. Each group included 10 samples. Also 20 roots were used as positive and negative control samples, in the negatives the entire root surface was coated with 2 layers of nail varnish and positives were unfilled root-end preparation. Statistical analysis consisted of the Kruskal-Wallis test and Pairwise comparison.

There were no significant differences in apical microleakage after 24 h and 1 week in the experimental groups. In the 3rd month, samples with 90° bevel and 4-mm-thick MTA showed significant statistical differences with all samples with 45° and 60° bevels and depths of 2- and 3-mm-thick MTA (P<0.05).

This in vitro study showed that when the resection angle is 90°, retrograde depth does not affect microleakage, but resection angles other than 90°, require 4 mm-retrograde depth to be sealed.

Statement of the Problem: The endodontically treated teeth usually suffer from the discoloration induced by endodontic materials, which can adversely affect the esthetical outcome of a treatment. This study aimed to compare the discoloration caused by the silver nanoparticles coated with imidazolium as an irrigant, sodium hypochlorite (NaOCl), and chlorhexidine gluconate (CHX). The root tips of 65 single-rooted human teeth were resected and root canal systems were chemomechanically prepared from the apical aspect. The specimens were randomly divided into three experimental (n=15) and two control groups (n=10). In the experimental groups, the substance was placed in the root canal for 30 minutes, and then washed with normal saline. Saline or blood alone was used in the control groups. The discoloration was assessed spectrophotometrically right after substance placement (T1), 1 week (T2), and 1 (T3) and 3 months (T4) after and color change values were calculated. Statistical analysis was performed using multi-sample repeated measures analysis of variance, Tukey's HSD, and Sidak tests. In T1, there was no significant difference in color change between silver nano particle, blood and CHX (p> 0.05); but these three groups had significantly more ∆E value than NaOCl and Normal Saline (p< 0.05). NaOCl and normal saline had no significant difference in T1 (p> 0.05). In T2, T3 and T4 results were the same and showed blood and silver nano particle had significantly higher color change in comparison with NaOCl, CHX and normal saline (p< 0.05). There was no significant difference between NaOCl, CHX, and normal saline in tooth discoloration (p> 0.05). There was no significant difference between silver nano particle and blood in ability of tooth discoloration (p> 0.05). Within the limitation of this study, silver nano particle material could not be suggested as an intra-canal irrigant regarding its unfavourable tooth discoloration.

The aim of this in vitro study was to evaluate the effect of various irrigants on the push-out bond strength of calcium-enriched mixture (CEM) cement and mineral trioxide aggregate (MTA).
Methods and Materials: A total of 140 dentin disks with a thickness of 1.5±0.2 mm and lumen size of 1.3 mm, were randomly divided into 12 groups (n=10) and 4 control groups (n=5). The lumen of disks in groups 1, 2, 3, 7, 8, 9 were filled with CEM and groups 4, 5, 6, 10, 11, 12 were filled with MTA. Control groups were filled with CEM and MTA. Specimens were incubated at 37°C for one day in groups 1 to 6 and seven days in groups 7 to 12. After incubation the samples were divided into three subgroups (n=10) that were either immersed for 30 min in 5.5% sodium hypochlorite (NaOCl), 2% chlorhexidine (CHX) or saline solution. The push-out bond strength values were measured by using a universal testing machine. The nature of the failures were determined by light microscope. Data was analyzed using the three-way ANOVA to evaluate the effect of material type, different irrigants and time intervals. Post hoc Tukey’s test was used for two-by-two comparison of the groups.
CEM cement significantly showed a higher push-out bond strength in comparison with MTA (P=0.001). The elapse of time significantly increased the bond strength (P=0.001). There was no significant difference between the irrigants used in this study (P=0.441). Bond failure was predominantly of mixed type in MTA and of cohesive type in CEM samples.
Based on this study, endodontic irrigants did not influence the push-out bond strength of MTA and CEM cement.

Statement of the Problem: Insolubility is an important criterion for an ideal root-end filling material to both prevent any microleakage between the root canal and the periradicular space and provide sealing ability. Many recent studies have shown that mineral trioxide aggregate (MTA) and calcium-enriched mixture (CEM) have acceptable sealing ability. The purpose of this in vitro study was to evaluate the solubility of these root-end filling materials. Forty stainless steel ring moulds with an internal diameter of 10±1 mm and a height of 2±0.1 mm were selected. Samples of MTA and CEM were mixed according to the manufacturer’s instructions and inserted into the moulds. The specimens were divided into 4 experimental groups and kept in synthetic tissue fluid (STF) for 2 different time periods (7 and 28 days). The control group contained 8 empty rings. The moulds’ weights were recorded before and after immersion in STF. The changes in the weight of the samples were measured and compared using a two- way ANOVA test at a significance level of 5%. Specimens were evaluated with scanning electron microscopy (SEM) at a magnification of 500×. There was no significant difference in weight changes between MTA and CEM samples (p> 0.05).

The aim of this experimental laboratory study was to evaluate the effect of different mixing and placement techniques on compressive strength (CS) of calcium-enriched mixture (CEM) cement. Methods and Materials: CEM powder was mixed with its liquid either by hand mixing or amalgamator mixing. The mixture was loaded to cylindrical acrylic molds with 6.0±0.1 mm height and 4.0±1 mm diameter. Half of the specimens in each group were selected randomly and ultrasonic energy was applied to them for 30 sec. All samples were incubated for 7 days at 37°C. The CS test was performed by means of a universal testing machine. The data were analyzed by the two-way analysis of variance (ANOVA) and Tukey’s post hoc tests. The level of significance was set at 0.05. The maximum CS was seen in the amalgamator-mixed samples that did not receive ultrasonic agitation. The CS value of amalgamator-mixed samples was significantly higher than manually-mixed ones (P=0.003). Ultrasonic vibration did not change the CS of specimens. According to the results, mixing with amalgamator increases the CS of CEM cement, while ultrasonic vibration had no positive effect.

The aim of this study was to evaluate the compressive strength of calcium-enriched mixture (CEM) cement in contact with acidic, neutral and alkaline pH values. Methods and Materials: The cement was mixed according to the manufacturer’s instructions, it was then condensed into fourteen split molds with five 4×6 mm holes. The specimens were randomly divided into 7 groups (n=10) and were then exposed to environments with pH values of 4.4, 5.4, 6.4, 7.4, 8.4, 9.4 and 10.4 in an incubator at 37° C for 4 days. After removing the samples from the molds, cement pellets were compressed in a universal testing machine. The exact forces required for breaking of the samples were recorded. The data were analyzed with the Kruskal-Wallis and Dunn tests for individual and pairwise comparisons, respectively. The level of significance was set at 0.05. The greatest (48.59±10.36) and the lowest (9.67±3.16) mean compressive strength values were observed after exposure to pH value of 9.4 and 7.4, respectively. Alkaline environment significantly increased the compressive strength of CEM cement compared to the control group. There was no significant difference between the pH values of 9.4 and 10.4 but significant differences were found between pH values of 9.4, 8.4 and 7.4. The acidic environment showed better results than the neutral environment, although the difference was not significant for the pH value of 6.4. Alkaline pH also showed significantly better results than acidic and neutral pH. The compressive strength of CEM cement improved in the presence of acidic and alkaline environments but alkaline environment showed the best results.

This laboratory study was performed to evaluate the effect of different acidic pH values on the push-out bond strength of calcium-enriched mixture (CEM) cement. Methods and Materials: Forty-eight root dentin slices were obtained from freshly extracted single rooted human teeth and their lumen were instrumented to achieve a diameter of 1.3 mm. Then, CEM cement was mixed according to manufacturers’ instruction and placed in the lumens with minimal pressure. The specimens were randomly divided into four groups (n=12) which were wrapped in pieces of gauze soaked in either synthetic tissue fluid (STF) (pH=7.4) or butyric acid which was buffered at pH values of 4.4, 5.4 and 6.4. They were then incubated for 4 days at 37°C. The push-out test was performed by means of the universal testing machine. Specimens were then examined under a digital light microscope at 20× magnification to determine the nature of the bond failure. The data were analyzed using the Kruskal-Wallis test followed by Dunn’s test for pair-wise comparisons. The highest push-out bond strength (10.19±4.39) was seen in the pH level of 6.4, which was significantly different from the other groups (P<0.05). The values decreased to 2.42±2.25 MPa after exposure to pH value of 4.4. Lower pH value of highly acidic environments (pH=4.4), adversely affects the force needed for displacement of CEM cement; while in higher pH values (pH=6.4) the bond-strength was not affected. CEM cement is recommended in clinical situations where exposure to acidic environment is unavoidable.

Many of highly-alkaline dental materials have some adverse effects on physical properties of dentin. As basic substances, mineral trioxide aggregate (MTA), calcium hydroxide (CH) and the new endodontic material, calcium-enriched mixture (CEM) cement, may adversely affect dentin. The purpose of this in vitro study was to evaluate the effect of long-term application of CEM cement, MTA and CH on flexural strength of bovine dentin. Three hundred and twenty bovine dentin samples were divided into 4 groups, which were either exposed to CEM cement, CH, MTA or normal saline (control group). Samples of each group were divided into 4 subgroups which were tested by means of Instron Universal Testing Machine for periods of 7, 30, 180 and 365 days after exposure to the test materials. The required force for sample breakage was recorded. The data were analyzed by the two-way ANOVA and Tukey tests. The mean value of forces to break the samples in CEM cement and CH groups was significantly lower than the control group after 1 month (P<0.05). After 180 days, the samples of CEM cement group retrieved their strength but in MTA and CH groups the time interval weakened the samples. After one year of exposure to CH and MTA, flexural strength of the dentin reduced to 72% and 38.7%, respectively (P<0.05). Yet the flexural strength of samples in CEM cement group did not change significantly compared to control group. Following 365 days of application of experimental materials to bovine dentin, the CEM cement showed an interesting result and the samples in this group reached their initial strength during the first week of the study but the other materials caused a reduction in dentin strength at the end of the study.

Epidemiological considerations indicate the importance of prevention، diagnosis and treatment planning. The aim of this study was to assess the prevalence of different types of traumatic dental injuries (TDI) and their etiology in patients referred to Shiraz Dental School in order to find a reliable preventive pattern for TDI. This descriptive‒analytical study examined the files of 314 patients، who referred to Shiraz Dental School (2008‒2012)، with 554 traumatized teeth. The variables investigated included age، sex، type of the involved tooth، type of TDI، place of occurrence، reason for injury and intervals between injuries and the time of referral to Shiraz Dental School. Kruskal-Wallis and Mann-Whitney tests were used for statistical analysis and comparison of TDIs based on demographic data using SPSS 16 (α=0. 05). Of all the patients، men and women accounted for 65. 9% and 34. 1%، respectively. The mean age was 17. 37 years. In average، the number of traumatized teeth in all the files was more than 1 tooth. The most frequent traumatized teeth were permanent maxillary first incisors (64. 4%). Falls were the most frequently cited etiological factors in TDI (33. 7%)، followed by car accidents (25. 2%) and complicated crown fracture was the most common TDI (20. 2%); 64. 9% of patients had referred to Shiraz Dental School less than one month after trauma. No significant differences were observed between males and females in the frequency and mean age of the trauma types (p value > 0. 005). Based on the results of the present study، falls (33. 8%) and car accidents (25. 2%) were the most frequent etiologic factors for TDI، respectively، with the streets as the most frequent place of accidents (44. 9%).

Some studies in dental literature have proposed that short term and long term exposure of root dentin to calcium hydroxide predisposes it to fracture. Mineral trioxide aggregate (MTA) and a recently introduced endodontic material, calcium-enriched mixture (CEM) cement may be used instead of calcium hydroxide and might have an effect on the strength of root dentin. Therefore, the aim of this in vitro study was to compare the short-term effect of calcium hydroxide, MTA and CEM cement on the strength of bovine root dentin. In this experimental study, 15 freshly extracted intact bovine incisors were selected. A cylinder with uniform wall thickness (internal diameter of 2.5 and external diameter of 5.5) was prepared. The cylinders were cut longitudinally into 4 symmetrical pieces. The 60 prepared samples were divided into four groups (n =15). The samples were placed in 4 petri-dishes containing calcium hydroxide, MTA, CEM cement and normal saline as the control group. They were then subjected to flexural forces applied by Instron universal machine. Data was analyzed using ANOVA and Tukey test. The mean flexural force in the calcium hydroxide, MTA and CEM cement groups was significantly lower than that in the control teeth (77.9 N, 90.66 N, 94.40 N, compared to 125.12 N respectively, P=0.001). There were no significant differences between calcium hydroxide, MTA and CEM cement group. MTA and CEM cement decreased the flexural strength of bovine root dentin, like their counterpart calcium hydroxide. Further studies are required to determine the effect of these materials on human root dentin clinically.

The crown-root fracture is a common tooth injury which compromises the biological width and need proper endodontic and prosthodontic treatment to achieve acceptable clinical outcome. This case report describes clinical management of crown-root fracture in maxillary central incisors which was successfully treated by forceps eruption with 180˚ rotation to restore the biological width. The patient was followed-up for 18 months. Clinical and radiographic evaluation showed acceptable results, the replanted teeth have normal function and no obvious inflammatory root resorption was seen on radiographic examination.

Bacterial infection of tooth pulp can progress into periapical diseases. Root canal treatment has been established as the best treatment. In cases of failure, nonsurgical retreatment of teeth is preferred to surgical procedure and extraction. In this historical cohort study, 104 permanent teeth with apical lesion were treated during 2002-2008. All teeth showed radiographic evidence of periapical lesion varying in size from 1 to >10mm. A total of 55 teeth were treated with initial root canal treatment and 49 teeth required retreatment. Patients were recalled up to ≈7 years. All radiographs were taken by RSV MAC digital imaging set and long cone technique. The presence/absence of signs and symptoms and periapical index scores (PAI) were used for measuring outcome. Teeth were classified as healed (clinical/radiographic absence of signs and symptoms) or diseased (clinical/radiographic presence of signs and symptoms). The data were statistically analyzed using student t-test and Pearson chi-square or fisher’s exact test. The rate of complete healing for teeth with initial treatment was 89.7%, and for retreatment group was 85.7%; there was no significant difference. Size of lesions did not significantly affect the treatment outcomes. Success of tooth treatment did not reveal significant correlation with gender and number of roots. Orthograde endodontic treatment/retreatment demonstrates favorable outcomes. Thus, nonsurgical endodontic treatment/retreatment should be considered as the first choice in teeth with large periapical lesion.

Background and aims. Trauma is one of the major factors associated with temporomandibular joint disorders (TMD). These disorders result from macro-trauma or micro-trauma. Macro-trauma might be iatrogenic; for example, from intubation procedures, third molar extraction procedures, and lengthy dental appointments. The aim of this study was to evaluate the effect of lengthy root canal therapy (more than 2 hours) on TMJ and its supporting structures.Materials and methods. Eighty patients whose root canal therapy session lasted more than 2 hours were examined for the status of TMJ and masticatory muscles. After one week the second part of the examination was carried out for TMJ problems and pain and tenderness levels of masticatory muscles. Data was analyzed using Wilcoxon statistical test.Results. Women showed more pain compared to men. There was a significant increase in pain in the external acoustic meatus examination one week after root canal therapy. Patients who were treated for their posterior teeth suffered more pain than those who were treated for the anteriors and premolars. Other aspects of the examination were not affected significantly by lengthy root canal therapy.Conclusion. Lengthy dental treatments can harm TMJ and masticatory muscles and wide opening of the mouth during such appointments can worsen the situation. Therefore, it is wise to break the appointment into shorter intervals and let the patients rest during treatment to close their mouth to prevent iatrogenic damage to TMJ.

Diseases of the dental pulp and periapical tissues are chiefly caused by microorganisms. Antibiotics are used in some endodontic cases; however, successful cases can predominantly be achieved by mechanical and chemical cleaning of the canal or surgical intervention. The aim of this study was to determine the knowledge of General Dental Practitioners (GDPs) in Shiraz in respect to antibiotic prescriptions during and after endodontic treatment. A one-page questionnaire was sent to 200 active general dentists. Of the 120 surveys returned, 93 were accepted. The data were analyzed using t-test, Chi-square, ANOVA and Fisher’s Exact Test. Only 29% of dentists had full knowledge (correct answers to all questions) of antibiotic prescription protocols in pulpal and periapical disease. Amoxicillin 500 mg capsule was the drug of choice of dentists. Total of 42% of GDPs had full knowledge of antibiotic prescription protocols for persistent or systemic infections cases. GDPs more recently qualified had slightly greater knowledge compared to GDPs with experience; however, this difference was not significant. Also, there was no significant difference between genders. General practitioners’ knowledge about antibiotics seems inadequate and further education is recommended to update the practitioners.

Preparation techniques and instruments produce and push debris out of canals. This can induce inflammation within the periapical area. Therefore, instrumentation that causes less extrusion of debris is more desirable. The purpose of this in vitro study was to evaluate the quantity of debris extruded from the apical foramen during root canal preparation by using one hand and two rotary instrumentation techniques. Three different groups each with 12 mesiobuccal roots of human maxillary first molar were instrumented using either step-back technique with hand instruments, FlexMaster or Mtwo rotary system. Debris extruded from the apical foramen during canal preparation was collected. The mean dry weights of debris were compared using one-way ANOVA. Step-back group had a significantly greater mean weight of debris compared to the other two groups (P<0.05). Mtwo group had the lowest mean weight of debris, though it was not significantly different from FlexMaster group. According to this study, the engine driven techniques were associated with less apical debris extrusion.