The effect of cone beam computerized tomography voxel size and the presence of root filling on the assessment of middle mesial canals in mandibular molar teeth.

INTRODUCTION: The study aims to compare the detection of the middle mesial canal (MMC) in mandibular molar teeth using cone beam computed tomography (CBCT) with different voxel sizes when the mesiobuccal (MB) and mesiolingual (ML) canals have three distinct phases (unpreparation, preparation and obturation and the removal of the obturation and repreparation). METHODS: Two hundred forty-two extracted human mandibular molars were collected and kept in a physiological saline solution prior to use. 0.2-, 0.28- and 0.35-mm voxel sizes CBCT (n = 242) were performed in three phases (Ph): Ph1, no MB and ML canal preparation or obturation; Ph2, after MB and ML canals preparation and obturation; and Ph3, after the removal of the obturation of MB and ML canals and canals repreparation. Images were analyzed using OnDemand3D® software. After the CBCT acquisition in Ph3, all the samples were clarified to visualize the presence of the MMC directly. A blinded, previously calibrated examiner analyzed all the images. RESULTS: The MMC was detected in 15 of the 242 teeth after the clearing technique. The lowest MMC detection rate was observed at 0.35-mm voxel size regardless of the ML and MB canal condition, while the highest was observed at 0.2-mm voxel size (P < 0.05). There is no statistically significant difference between 0.2-mm and 0.28-mm voxel sizes (P > 0.05). In all voxel sizes, the highest rate of detectability of the MMC was seen in Phase 1, while the lowest was in Phase 2. CONCLUSIONS: It may be appropriate to take a 0.20-mm voxel size CBCT image, especially after the removal of root canal filling. CLINICAL RELEVANCE: An appropriate CBCT voxel size and the absence of root canal filling in the root canal system help to detect the missing MMC.

Fracture resistance of primary molars after pulpotomy procedure using mineral trioxide aggregate or Biodentine.

In this study, the effect of mineral trioxide aggregate (MTA) and Biodentine on the resistance to fracture of pulpotomized primary molars was evaluated. 75 primary molars were divided into 2 control groups (positive and negative) and 3 experimental groups with 15 teeth each. No treatment was applied to the teeth in the negative control group. In the teeth in the positive control group, pulpotomy cavities were performed, but not filled. In the teeth in the experimental group, pulpotomy cavities were performed, and filled as follows. Group 3: mineral trioxide aggregate + glass ionomer cement (GIC); Group 4: Biodentine + GIC and Group 5: zinc oxide-eugenol + GIC. Final restorations in teeth in all experimental groups were completed with composite filling material. 75 teeth were then subjected to fracture resistance testing. Obtained data were analyzed statistically. Sorting by fracture resistance; Group1 > Group 4 > Group 3 = Group 5 > Group 2 (p < 0.05). Restorable fracture type was predominant in experimental groups (p < 0.05). The use of Biodentine in teeth undergoing pulpotomy in primary teeth can be preferred as a suitable base material to increase resistance to fracture.

Effect of different final irrigation agitation techniques on root canal dentin tubule penetration of nanoparticle calcium hydroxide dressing.

This study is aimed to assess the efficacy of different final irrigation agitation techniques on dentin tubule penetration of nanoparticle calcium hydroxide (NCH) dressing. Ninety-six extracted upper incisors were shaped up to #40file. Then, Four experimental groups were formed according to the final irrigation procedure: conventional needle irrigation (CNI), manual dynamic agitation (MDA), sonic agitation (SA) and ultrasonic irrigant agitation (UIA). According to the intracanal drug used, these groups were divided into two subgroups: calcium hydroxide (CH) and NCH. Prepared CH preparations were labelled with Rhodamine B, and CH or NCH were placed in root canals. In the UIA group, both CH and NCH had the highest penetration depth and percentage compared to the other groups (p < 0.05). The penetration depth and percentage of NCH in the UIA and SA groups were significantly higher than in the CH groups (p < 0.05). UIA is more effective than other groups in increasing dentinal tubule penetration of CH and NCH.

Efficacy of different irrigation agitation systems in the removal of root canal sealers from artificial standardised grooves.

The present study aims to assess the efficacy of different irrigation agitation systems in removing calcium silicate-based sealers from artificial standardised apical grooves. After the root canal instrumentation of 96 teeth, artificial apical grooves were created in half of each root. The samples were divided into two main groups according to the sealer type (AH Plus Jet [APJ] and Sure-Seal Root™ [SSR]) (n = 48). The root halves were then reassembled and divided into four experimental groups based on the final irrigation technique used: Conventional Syringe Irrigation (CSI), Ultrasonic Irrigant Agitation (UIA), Sonic Agitation (SA) and Manual Dynamic Agitation (MDA). The roots were then dissembled to assess the amount of root canal sealer. UIA significantly removed more of SSR sealer than CSI, MDA and SA while there was no statistical difference between CSI, MDA, SA and UIA groups in the APJ group. None of the irrigation agitation systems used had completely removed the APJ and SSR sealers. However, UIA was more effective in removing SSR sealer from the standardised apical groove than were CSI, MDA and SA.

Effect of different coronal restorations on the fracture resistance of teeth with simulated regenerative endodontic treatment: An in vitro study.

This study investigated the effect of different coronal restorations on the fracture resistance (FR) of immature teeth with simulated regenerative endodontic treatment. A total of 120 lower premolars were divided into eight groups. Except for negative control, the root canals were instrumented with rotary files and Peeso reamers. Fifteen instrumented teeth were acted as positive control (unrestorated). In the remaining 90 teeth, regenerative endodontic treatment procedures were performed. Ninety teeth were randomly divided into 6 groups according to coronal restoration type; Filtek Z550, Filtek Bulk fill Restorative (FBR), SDR+Filtek Z550, EverX+Filtek Z550, Ribbond+FBR and Ribbond+SDR+Filtek Z550. After thermal ageing, the restorated teeth were subjected to vertical loading force. FR values was obtained as follows: Negative control > Ribbond+FBR = Ribbond+SDR+Filtek Z550 > Filtek Z550 = FBR =SDR+Filtek Z550 = EverX+Filtek Z550 > Positive control, (P < 0.05). The use of Ribbond in combination with composite resin enhanced the FR of teeth.

The effect of low-level laser therapy on the success rate of inferior alveolar nerve blocks in mandibular molars with symptomatic irreversible pulpitis: A randomized clinical trial.

AIM: To evaluate the effect of low-level laser therapy (LLLT) on the success rate of inferior alveolar nerve blocks (IANB) in mandibular molar teeth with symptomatic irreversible pulpitis (SIP). METHODOLOGY: Eighty-eight patients who were diagnosed with SIP were randomly divided into two groups: the group in which only IANB was applied and the group in which IANB + LLLT was applied. IANB was applied to patients in the control group with 4% articaine. LLLT was applied to the patients in the experimental group in addition to IANB. The pain experienced during the operation was evaluated using a visual analog scale. If the patients reported moderate or severe pain during the treatment, the IANB was defined as unsuccessful. Pearson's chi-square test was used to analyse anaesthetic success rates. RESULTS: Whilst the anaesthesia success rate was 34% in the group where only IANB was applied, it was 57% in the group in which LLLT was applied in addition to IANB. There was a significant difference between the groups (p = .032). CONCLUSIONS: The application of LLLT to support IANB in mandibular molar teeth with SIP increased the success of anaesthesia. However, it was insufficient for a complete pulpal anaesthesia.

Effect of calcium hydroxide mixed with lidocaine hydrochloride on postoperative pain in teeth with irreversible pulpitis and symptomatic apical periodontitis: a preliminary randomized controlled prospective clinical trial.

OBJECTIVES: To investigate the effect of calcium hydroxide mixed with lidocaine HCl on postoperative spontaneous pain. MATERIALS AND METHODS: Sixty patients having irreversible pulpitis and symptomatic apical periodontitis with a preoperative spontaneous pain and percussion pain which was more than 50 on a visual analogue scale (100 mm VAS) were included in this study. After the preparation of the root canals, the patients were randomly distributed into two groups according to the calcium hydroxide vehicle, control group (mixed with saline) and calcium hydroxide mixed with lidocaine HCl (n = 30). Postoperative spontaneous pain scores were recorded by a VAS every day for a week. Data were analysed using one-way analysis of variance, chi-squared test and Mann-Whitney U tests (p = 0.05). RESULTS: The calcium hydroxide mixed with lidocaine HCl group resulted in significantly less pain compared with the calcium hydroxide mixed with saline group during days 1 to 4 (p < 0.05). There were no significant differences between the groups in terms of postoperative percussion pain levels (p > 0.05). CONCLUSION: Within the limitations of this study, it can be concluded that the calcium hydroxide mixed with lidocaine HCl can be beneficial in reducing postoperative pain in teeth with irreversible pulpitis and symptomatic apical periodontitis. CLINICAL RELEVANCE: The calcium hydroxide mixed with lidocaine HCl can be beneficial in reducing postoperative pain in teeth with irreversible pulpitis and symptomatic apical periodontitis. CLINICAL REGISTRATION NUMBER: TCTR20181121003.

Evaluation of apically extruded debris during the canal preparation using new heat-treated nickel-titanium files in curved canals.

This study compared the amount of apically extruded debris associated with different heat-treated Ni-Ti rotary systems during the preparation of curved root canals of mandibular molars. Sixty extracted human mandibular molars were selected. EdgeFile, K3XF, OneCurve (OC) and ROTATE files were used to prepare both mesial canals of teeth. The initial weight of each Eppendorf tube to be used was calculated using an analytical balance prior to instrumentation. After instrumentation, the tubes were then stored for 5 days in an incubator at 70°C. Each tube was reweighed, and the weight of the dry extruded debris was established by subtracting the pre-instrumentation and post-instrumentation weight of the Eppendorf tubes for each group. All files caused apical extrusion of debris. There was no statistical difference between the ROTATE, EdgeFile, OC and K3XF systems (P > 0.05). All the heat-treated Ni-Ti rotary systems led to similar apical debris extrusion during the canal preparation.

The effect of two different irrigation needles on post-operative pain after pulpectomy in primary molar teeth: A randomized clinical study.

BACKGROUND: Post-operative pain (PP) following pulpectomy is of concern for endodontic patients and dentists. AIM: This study evaluated the intensity of PP following pulpectomy in primary maxillary molars, using two irrigation needles. DESIGN: One hundred patients in ages ranging from 6-9 years requiring pulpectomy for asymptomatic primary teeth with non-vital pulp were included in the study. The participants were randomly assigned to two groups of 50 patients each, according to the type of irrigation needle used, that is, a conventional open-ended needle and a double side-vented needle. The teeth were obturated and then permanently restored. The presence of PP was assessed after six, 12, 24, 48, and 72 hours, and finally after one week, using a four-point pain intensity scale. The PP scores were then statistically analysed. RESULTS: In 6, 12, and 24 hours time intervals, patients who had their teeth irrigated with the open-ended needle exhibited more intense PP than those who had their teeth irrigated with a double side-vented needle (P < .05). After 48 hours, 72 hours, and 1 week, however there was no significant difference between the groups (P > .05). CONCLUSIONS: Side-vented needles may be preferred in order to decrease PP at the first 24 hours after pulpectomy in primary molars.

Duration of ultrasonic activation causing secondary fractures during the removal of the separated instruments with different tapers.

OBJECTIVES: The aim of the present study was to determine the effect of taper (.08, .06, and .04) of separated K3XF instruments on duration taken for the secondary fracture formation during ultrasonic activation. MATERIALS AND METHODS: Ten 25/.08 K3XF (SybronEndo, Orange, CA, USA), ten 25/.06 K3XF, and ten 25/.04 K3XF instruments were used for the study. The apical 5 mm of the instruments was cut to simulate the fragments in root canals. Fragments of the instruments were sandwiched between two straight dentin blocks. An ultrasonic tip was used to cause a secondary fracture of the fragment. The time needed for the secondary fracture was recorded for each instrument. The data were statistically analyzed using the Kruskal-Wallis H test (alpha = 0.05). RESULTS: Secondary fractures occurred in all instruments. In the .08 taper group, secondary fractures took longer than in the case of the .06 and the .04 taper groups (P < 0.05). There were no significant differences between the .06 and the .04 taper groups in terms of the time required for the occurrence of a secondary fracture (P > 0.05). CONCLUSIONS: In the .08 taper group, secondary fracture took longer time than in the case of the .06 and the .04 taper groups due to its larger cross-sectional area involved. CLINICAL RELEVANCE: Typically, when removing separated instruments, a much lower power setting is chosen. The purpose of this in vitro study was to determine which tapered files were more resilient to secondary fracture, thus allowing a higher power setting to be chosen. Thus, the results of the present study cannot be used in clinical practice. If the clinician knows the taper of the broken file, the clinician should be very careful with regard to secondary fractures when using ultrasonics to remove the separated smaller tapered instruments.

Effect of two different temperatures on resistance to cyclic fatigue of one Curve, EdgeFile, HyFlex CM and ProTaper next files.

This study compared the cyclic fatigue resistance (CFR) of three controlled memory (CM) nickel-titanium rotary files (One Curve, EdgeFile and HyFlex CM) in comparison with a file (ProTaper Next) made from M-wire nickel-titanium alloy at two different temperatures (room and intracanal) in an s-shaped canal. One hundred and sixty files were tested to determine the CFR of OneCurve, EdgeFile, HyFlex CM and ProTaper Next in an artificial canal at room and at intracanal temperature. The number of cycles to failure was recorded, and data were analysed. At both temperatures, ProTaper Next exhibited the lowest CFR compared with the other files (P < 0.05). At room temperature, there was no difference among the three CM files regarding CFR (P > 0.05). At intracanal temperature, OneCurve and EdgeFile exhibited more CFR than the HyFlex CM (P < 0.05). Testing at intracanal temperature caused a significant decrease in CFR of all tested files compared with testing at room temperature.

Histologic Evaluation of Regenerated Tissues in the Pulp Spaces of Teeth with Mature Roots at the Time of the Regenerative Endodontic Procedures.

INTRODUCTION: Recently, regenerative endodontic procedures (REPs) have been used to treat mature permanent teeth with apical periodontitis. Although animal studies with regard to histopathological findings after REPs exist, there is a paucity of studies on mature human teeth. As yet, the nature of tissues formed in the root canal of such teeth has not been established. This report presents histologic findings with regard to regenerative tissues in the pulp spaces exposed after dental trauma in human mature maxillary incisor teeth successfully treated with REPs. METHODS: A 20-year-old girl was referred to our clinic for the treatment of her central incisors (#8 and #9). The incisors had apical periodontitis. REPs were performed on both maxillary central incisors. Three years 5 months after the initial treatment, the teeth had a horizontal crown fracture and needed a fiber post as well as root canal treatment. Mineral trioxide aggregate was carefully removed, and the tissue that had formed in the canal space was processed for routine histologic and immunohistochemical examination. RESULTS: Histologic findings of the present case showed that the vital tissue formed in the canal space was fibrous connective tissue that contains bonelike tissue, vascular structures, and inflammation. These histologic findings obtained from mature teeth were similar to the findings of previous reports relating to immature teeth. CONCLUSIONS: Based on the present case, the vital tissue formed in the canal space is fibrous connective tissue that contains bonelike tissue, vascular structures, and inflammation. These histologic findings with regard to mature teeth were similar to the findings of previous reports relating to immature teeth.

Success of maintaining apical patency in teeth with periapical lesion: a randomized clinical study.

OBJECTIVE: The aim of this study was to evaluate the effect of maintaining apical patency on periapical healing and postoperative pain levels in teeth with necrotic pulp and apical periodontitis. METHOD AND MATERIALS: Fifty mature teeth with periapical lesions were randomly distributed into two treatment groups: patency, and nonpatency (n = 25). Patients were followed up over a 12-month period using clinical and radiographic assessments. The data were statistically analyzed using independent-samples t test and chi-square tests at a 95% confidence level (P = .05). RESULTS: Seventeen teeth in the patency group (85.0%) and 19 teeth in the nonpatency group (86.4%) were classified as being successfully treated (P = .900). CONCLUSIONS: Within the limitations of the present study, maintaining apical patency did not affect endodontic treatment outcomes.

The Effect of Cryotherapy Application on the Success Rate of Inferior Alveolar Nerve Block in Patients with Symptomatic Irreversible Pulpitis.

INTRODUCTION: This randomized clinical trial assessed the effect of preoperative intraoral cryotherapy application on the success rate of inferior alveolar nerve blocks (IANBs) in patients with symptomatic irreversible pulpitis (SIP). METHODS: One hundred four patients with SIP were randomly distributed into 2 groups: control and cryotherapy groups. In the control group, patients received an IANB injection with 2% lidocaine. In the cryotherapy group, intraoral cryotherapy application was performed for 5 minutes after the IANB. Endodontic therapy was then conducted 15 minutes after the IANB injection. If the patients reported moderate or severe pain during the procedure, the IANB was defined as "unsuccessful," and a supplementary injection was administered. RESULTS: All patients reported profound lip numbness. The overall success rate for the IANBs was 43.3%. In the cryotherapy group, the success rate of the IANBs was 55.8%, whereas in the control group it was 30.8% (P < .05). CONCLUSIONS: Intraoral cryotherapy application increased the success rate of IANBs in mandibular molar teeth with SIP. However, supplemental anesthesia techniques may still be required to provide profound pulpal anesthesia in many cases.

The Effect of Different Cavity Designs and Temporary Filling Materials on the Fracture Resistance of Upper Premolars.

INTRODUCTION: The aim of this study was to compare the fracture resistance of upper premolars undergoing root canal treatment that had been temporarily restored with 4 different temporary filling materials. METHODS: This study was based on 120 extracted upper premolars. Eight teeth were left intact and served as the negative control group. Mesio-occluso-distal cavities with 2 different designs were prepared for the rest of the teeth (for group 1 a width of one third of the intercuspal distance and for group 2 a width of two thirds of the intercuspal distance). Then, the endodontic access cavities were prepared, and the root canals instrumented with Revo-S rotary files (MicroMega, Besancon, France). Thereafter, a total of 16 teeth consisting of 8 each from group 1 and group 2 served as the positive control group and did not have any temporary filling material. The teeth were randomly divided into 4 subgroups (n = 12) according to the temporary filling material: Cavit G (3M ESPE, St Paul, MN), Coltosol F (Coltène/Whaledent AG, Altstätten, Switzerland), Intermediate Restorative Material (Dentsply Sirona, Konstanz, Germany), or DiaTemp (DiaDent Europe BV, Almere, Netherlands). Each specimen was then subjected to a fracture resistance test using a universal testing machine until the fracture occurred. The force required to fracture each specimen was recorded, and the data were statistically analyzed. RESULTS: The negative control group showed the highest fracture resistance values compared with the other groups, whereas the positive control groups showed the lowest fracture resistance values. There were no statistically significant differences in the fracture resistance of upper premolar teeth undergoing root canal treatment among Cavit G, Intermediate Restorative Material, Coltosol F, and DiaTemp, regardless of the cavity width (P > .05). CONCLUSIONS: The cavity design was found to be an effective factor on the fracture resistance of upper premolar teeth undergoing root canal treatment. The temporary filling materials tested did not affect the fracture resistance.

The Effect of Different Irrigation Agitation Techniques on Postoperative Pain in Mandibular Molar Teeth with Symptomatic Irreversible Pulpitis: A Randomized Clinical Trial.

INTRODUCTION: This study compared the effect of several final irrigation agitation techniques (sonic agitation, passive ultrasonic irrigation, and manual dynamic agitation [MDA]) in comparison with needle irrigation on postoperative pain in mandibular molar teeth with symptomatic irreversible pulpitis. METHODS: One hundred sixty-eight patients with a single tooth diagnosed as symptomatic irreversible pulpitis were selected. Teeth were randomly assigned to 4 groups based on the final irrigation methods. In group 1 (needle irrigation), irrigation was conducted without agitation with a side-port needle; in group 2, sonic agitation was used; in group 3, passive ultrasonic irrigation was used; and in group 4, MDA was used. Teeth were then obturated with gutta-percha and a resin-based sealer using the cold lateral compaction technique. The presence of postoperative pain was assessed after 6, 24, 48, and 72 hours and 1 week. RESULTS: At the 6- and 24-hour time intervals, group 4 patients reported more intense postoperative pain than those patients in groups 1, 2, and 3 (P < .05). There was no significant difference among the groups at the other time intervals (P > .05), and in all groups the intensity of postoperative pain decreased over time. CONCLUSIONS: MDA caused greater postoperative pain after endodontic therapy in mandibular molar teeth with symptomatic irreversible pulpitis compared with the other methods in the first 24 hours.

Cyclic fatigue resistance of new reciprocating files (Reciproc Blue, WaveOne Gold, and SmartTrack) in two different curved canals.

AIM: In the present study, we compared the cyclic fatigue resistance (CFR) of Reciproc Blue, WaveOne Gold, and SmartTrack files in curved artificial canals. METHODS: Ninety new Reciproc Blue R25, WaveOne Gold Primary, and SmartTrack X1 files were tested in artificial canals with 45° and 60° angles of curvature. CFR was determined by recording the time to fracture in the artificial canals. Two-way analysis of variance was used to analyze the data. RESULTS: In the canal with a 45° angle of curvature, no significant differences were observed amongst Reciproc Blue, WaveOne Gold, and SmartTrack (P > .05). In the canal with a 60° angle of curvature, Reciproc Blue and SmartTrack had a greater CFR than WaveOne Gold (P < .05); there was no significant difference between the Reciproc Blue and SmartTrack files (P > .05). CONCLUSION: The results of the present study showed that Reciproc Blue and SmartTrack files exhibited greater CFR than WaveOne Gold only in canals with a 60° angle of curvature.

The Effect of Apical Positive and Negative Pressure Irrigation Methods on Postoperative Pain in Mandibular Molar Teeth with Symptomatic Irreversible Pulpitis: A Randomized Clinical Trial.

INTRODUCTION: This study compared the effect of conventional needle irrigation (positive pressure) and the EndoVac system (Discus Dental, Culver City, CA) (negative pressure) on postoperative pain in mandibular molar teeth with symptomatic irreversible pulpitis. METHODS: One hundred sixteen patients with symptomatic irreversible pulpitis were selected. Teeth were randomly assigned to 2 groups according to the irrigation methods performed during root canal preparation. In group 1, root canal irrigation was performed using a syringe and a 31-G side-port needle (NaviTip; Ultradent, South Jordan, UT). In group 2, the EndoVac system was used for irrigation. Teeth were then obturated with gutta-percha and a resin-based sealer using the cold lateral compaction technique. The presence of postoperative pain was assessed after 6, 24, 48, and 72 hours and 1 week. RESULTS: At 6-, 24-, and 48-hour time intervals, group 1 patients reported more intense postoperative pain than patients in group 2 (P < .05). There was no significant difference between the 2 groups at the other time intervals (P > .05), and in both groups the intensity of postoperative pain decreased over time. CONCLUSIONS: Apical positive pressure irrigation caused greater postoperative pain after endodontic therapy of mandibular molar teeth with symptomatic irreversible pulpitis compared with the apical negative pressure irrigation system.

Cyclic Fatigue Resistance of Reciproc Blue and Reciproc Files in an S-shaped Canal.

INTRODUCTION: This study evaluated the cyclic fatigue resistance (CFR) of Reciproc (R25 and R40; VDW, Munich, Germany) and Reciproc Blue (R25 and R40, VDW) instruments used in an artificial S-shaped canal. METHODS: A total of 80 files were tested in an S-shaped canal (n = 20 for each file, Reciproc R25 and R40 and Reciproc Blue R25 and R40). This study compared Reciproc R25 with Reciproc Blue R25 files and Reciproc R40 with Reciproc Blue R40 files. All files were rotated in an S-shaped artificial canal until fracture. CFR was determined by recording the time to fracture in the artificial canal. The length of each fractured fragment was measured in millimeters. An independent sample t test was used to analyze the data. RESULTS: Between the R25 files, Reciproc Blue instruments showed significantly greater CFR than the Reciproc files in the apical and coronal curves (P < .05). Between the R40 files, Reciproc Blue instruments exhibited greater CFR in the apical and coronal curves (P < .05). There was no difference in the fractured fragment lengths of the Reciproc Blue files compared with the Reciproc files (P > .05). CONCLUSIONS: The Reciproc Blue R25 and R40 files showed greater CFR than the Reciproc R25 and R40 files in an S-shaped canal.

Postoperative Pain After Root Canal Preparation with Hand and Rotary Files in Primary Molar Teeth.

PURPOSE: The purpose of this study was to evaluate the intensity and duration of postoperative pain after root canal preparation of primary maxillary molar teeth using two preparation techniques. METHODS: A total of 110 patients requiring pulpectomy for asymptomatic primary molar teeth with non-vital pulps were included in the study. The patients were randomly assigned to two groups of 55 patients each, according to the canal preparation method used. In Group one, teeth were prepared up to size 35 with hand files. In Group two, teeth were prepared up to size 35 with Revo-S rotary instruments. Following canal preparation, teeth were obturated with zinc-oxide eugenol paste and then permanently restored. The presence of postoperative pain was assessed after six, 12, 24, 48, and 72 hours and after one week, using a four-point pain-intensity scale. RESULTS: Except for those assessed after 72 hours and one week, patients who had their teeth prepared with hand files reported more intense postoperative pain than those who had their teeth prepared with Revo-S rotary files (P<0.05). In both groups, postoperative pain decreased over time. CONCLUSIONS: Hand files caused more postoperative pain after pulpectomy in primary maxillary molar teeth compared to the rotary system.