• Journal of Dental Anesthesia and Pain Medicine
• /
• 제22권4호
• /
• pp.267-275
• /
• 2022

Background: Various instrument kinematics used in single-visit endodontics influence the occurrence of pain after endodontic therapy. This study aimed to evaluate the occurrence of pain after mechanical instrumentation with Hyflex EDM (HEDM) and WaveOne Gold (WOG) during single-visit endodontic therapy. Methods: Sixty patients diagnosed with asymptomatic irreversible pulpitis and normal apical tissues in mandibular premolar teeth were included in the study for single-visit root canal therapy. The patients were divided into two groups (n = 30) according to the rotary instrument used during root canal preparation (group A [HEDM] and group B [WOG]). Pain was evaluated after endodontic therapy at 8, 24, and 48 h intervals using the visual analog scale (VAS). Data obtained were analyzed using the chi-square test, independent t-test, MannWhitney U test, and Wilcoxon matched-pairs test. Results: Statistically significant differences were observed between the two groups (P < 0.001) at 8, 24, and 48 h, with WOG exhibiting less pain than HEDM files. Conclusion: Postoperative pain was lower in the WOG file system than in the HEDM file system after single-visit root canal therapy at 8, 24, and 48 h.

• Restorative Dentistry and Endodontics
• /
• 제19권1호
• /
• pp.97-105
• /
• 1994

The purpose of this study was to evaluate the smear layer removing efficiency of two root canal preparation techniques. Twelve single-rooted teeth were used in two groups of six each. Group 1 was biomechanically prepared by hand using a K-file with a high volume of normal saline irrigation. Group 2 was. prepared by using ultrasonically activated K-file with a constant high volume of normal saline irrigation. After the experimental procedures, each root was split saggitally. The removing efficiency of the preparation methods were assessed in terms of surface condition of the canal walls at three levels, those coronal, middle, and apical thirds. On the basis of remaining debris, presence of smear layer, and patency of dentinal tubules, each canal was evaluated according to a scale form 0 to 2. A statistical analysis was used to indicated any significant differences in surface condition between the two methods. There was no statistical significance between hand instrumentation and ultrasonic instrumentation at the cervical third but removing efficiency of ultrasonic instrumentation was superior. No statistically significant differences were obhserved for middle or apical third.

• Restorative Dentistry and Endodontics
• /
• 제14권2호
• /
• pp.103-110
• /
• 1989

The purpose of this study was to evaluate the cleansing effect of Glyoxide on the dentinal walls of the root canal. Fourty teeth were divided into four groups and the canals in each group were individually enlarged with K-file by step-back technic and irrigated with one of four irrigants. The four used irrigants were Glyoxide (Marion lab. U.S.A.) in combination with 3.5% sodium hypochlorite, 3.5% sodium hypochlorite, 3.5% sodium hypochlorite in combination with 3% hydrogen peroxide and normal saline solution. All the irrigants were used in conjunction with instrumentation as they would be during clinical conditions. After final irrigation, the canals were dried with paper points and the teeth were split longitudinally. The cleaness of canal walls according to the size and the level of canals were evaluated under steroscope by t analysed statistically The results were as follows. 1. The use of 3.5% sodium hyphochlorite in combination with 3.0% hydrogen peroxide revealed the most clean canal surface regardless of the size of canal at apical third of root canal (p < 0.05). 2. Glyoxide in combination with 3.5% sodium hyphchlorite showed no significant difference in cleaning effect of canal surface compared with 3.5% sodium hypochlorite and normal saline solution at the apical third of narrow canal. 3. Glyoxide in combination with 3.5% sodium hypochlorite revealed no significant difference in debridement of canal walls compared with 3.5% sodium hypochlorite in combination with 3% hydrogen peroxide and saline solution at the middle third of narrow and large canals.

• Restorative Dentistry and Endodontics
• /
• 제23권1호
• /
• pp.477-486
• /
• 1998

Recently the development of rotary instrument makes it possible that in root canal treatment operator saves much more time, maintans original curved canal shape and easily prepares continuous tapered root canal. The purpose of this experiment was to examine the smoothness of the internal surface of prepared root canal and the effectiveness of debridement in prepared root canal by SEM for the comparison of hand and Ni-Ti rotary instrument. 25 extracted human teeth were access opened and # 10 K-type file was introduced into canal until it was appeared at the apical foramen. The working length was established by subtracting 0.5mm from this measurement. Group 1. The root canal preparation was done to # 30 with working length and then step-back until # 45 with K-Flexofile (Maillefer, Swiss). Group 2. Root canal preparation was done by Naviflex Ni-Ti file (Brasseler, USA) as the same technique with group 1. Group 3. Canal was prepared by Profile .04 (Maillefer, Swiss) taper until #30. Group 4. With use of Quantec (Tycom, USA) root canal was prepared from file number 1 to 8. In group 1 and 2, the root canal irrigant was NaOCl and the other groups, NaOCl and RC-prep (Premine Dental Products, USA) was used. The prepared teeth were notched with high-speed bur as bucco-lingual direction and fractured with chisel and mallet, then examined with SEM. Group 1 showed smooth internal surface. There were scratches mainly to the axial direction. Group 2 showed similar characteristics to those in group 1. Group 3 showed more smoother and linear cutting surface with bised scratches. Group 4 has the almost same characteristics group 3 and there was no difference in the file design. Ni-Ti rotary root canal instrument prepare the dentinal wall more smoother than hand instrument. The effectiveness of debridement was not fully affected by file design. The isthmus area and accessory canals of the root canal system were not prepared in any group. According to the result, hand and rotary type instrumentation techniques were effective in removal of major amount of tissue from root canal but it was not complete. In the direction of cutting movement there was difference between them.

• Restorative Dentistry and Endodontics
• /
• 제19권1호
• /
• pp.85-96
• /
• 1994

In this study, 24 curved resin blocks were prepared by one of the following four methods: 1) Conventional technique using K-flexo files 2) Step-back technique using K-flexo files 3) Crown-down technique using K-flexo files 4) Canal Master instrumentation using Canal Master Resin blocks were sectioned, photographed, and evaluated the mean centering ratio and the mean area of dentin removed before and after the instrumentation. The results were as follows : I. the mean centering ratio 1. In the level 1 and level 3, there was no significant difference in the mean centering ratio. 2. In the level 2, Step-back technique showed the worst mean centering ratio among the tested groups(p<0.001) and there was no significant difference between the other three groups. 3. In the level 4, Canal Master instrumentation and Step-back technique showed better mean centering ratio than the other two techniques(p<0.001) and there was no significant difference between the two techniques. II. the mean area of dentin removed 1. In the level l and level 3, there was no significant difference in the mean area of dentin removed. 2. In the level 2, Canal Master instrumentation removed less dentin than the other three techniques(P<0.01). 3. In the level 4, Crown-down technique removed less dentin than the other three techniques(P<0.05).

• 대한치과보존학회:학술대회논문집
• /
• 대한치과보존학회 2002년도 추계학술대회
• /
• pp.720-720
• /
• 2002

A number of investigations have shown that the presence of bacteria is prerequisite for developing pulpal and/or periradicular pathosis. Depending on the stage of pulpal pathosis, various species of bacteria can be cultured from infected root canals. Kakehashi et al. showed that exposure of pulpal tissue in germ-free rats was characterized by minimal inflammation and dentinal bridging while exposure of pulpal tissue in conventional rats with normal oral flora was characterized by pulpal necrosis, chronic inflammation, and periapical lesions. Currently used methods of cleaning and shaping, especially rotary instrumentation techniques, produce a smear layer that covers root canal walls and the openings to the dentinal tubules. The smear layer contains inorganic and organic substances that include fragments of odontoblastic processes, microorganisms, their by products and necrotic materials. Because of its potential contamination and adverse effect on the outcome of root canal therapy, it seems reasonable to suggest removal of the smear layer for disinfection of the entire root canal system. Presence of this smear layer prevents penetration of intracanal medications into the irregularities of the root canal system and the dentinal tubules and also prevents complete adaptation of obturation materials to the prepared root canal surfaces. Removal of the smear layer by an intracanal irrigant and placement of an antibacterial agent in direct contact with the content of dentinal tubules should allow disinfection of this complex system and better outcome for the root canal therapy. A new solution, which was a mixture of a tetracycline, an acid, and a detergent(MTAD), was developed in the Department of Endodontics, Dental School. Lorna Linda University, USA. It has been demonstrated that MTAD was an effective solution for the removal of the smear layer and does not significantly change the structure of the dentinal tubules when used as a final irrigant in conjunction with 1 % NaOCl as a root canal irrigant. Studies are in progress to compare the anti- microbial properties of this newly developed solution with those of sodium hypochlorite and EDTA that are currently used to irrigate the root canals and remove the smear layer from the surfaces of instrumented root canals.canals.

• Restorative Dentistry and Endodontics
• /
• 제24권4호
• /
• pp.623-627
• /
• 1999

During canal instrumentation of a curved canal, restoring force of endodontic instrument remove more dentin from the inner wall of the curvature. This effect tends to straighten the canal and thus may significantly shorten the working length. This study was to determine the mean reduction in working length after instrumentation according to the curvature. The curvature of mandibular mesial root was determined before instrumentation. 30 canals were divided into 3 groups each 10 on the basis of degree of curvature. Experimental groups as follows. In group 1, canals having curvature from 15 to 20 degrees: in group 2, canals having curvature from 20 to 30degrees; in group 3, canals having curvature above 30 degrees. Experimental teeth in all groups were accessed, and their actual working length determined by passing a size 15 K-file(IAF) just through the minor apical foramen. The canals were sequentially enlarged to size 35 with ProFile .06 series. The change of working length was calculated by measuring the tip of IAF beyond apical foramen by using stereomicroscope. The change of canal curvature following instrumentation were measured using the Schneider technique. The results were as follows. 1. The greatest changes of curvature and working length were observed in the group 3 canals(P<0.05), next were group 2 canals and group 1 canals(P>0.05). 2. Group 1 canals showed a mean reduction in 1.61 degrees and length of 0.12m respectively(P>0.05). 3. Group 2 canals showed a mean reduction in 3.42 degrees(P<0.05) and length of 0.25mm(P>0.05) respectively. 4. Group 3 canals showed a mean reduction in 7.23 degrees(<0.05) and length of 0.64mm respectively(P<0.05).

• 대한치과보존학회:학술대회논문집
• /
• 대한치과보존학회 2003년도 제120회 추계학술대회 제 5차 한ㆍ일 치과보존학회 공동학술대회
• /
• pp.547-547
• /
• 2003

The aim of this study was to compare the effects of three Ni-Ti instruments on leaning ability by evaluating the volumetric and morphological changes in the apical 6mm of the root canals before and after preparation, using three-dimensionally reconstructed root canals of extracted human teeth. Forty-five teeth were used in this study. They were opened the chambers and removed the all pulp remnants ultrasonically. Subsequently, the canal wall was coated with silver paste and prepared using ProTaper, ProFile and GT rotary files according to the manufacturers instructions. Before and after root canal preparation, all the specimens were scanned with micro computed tomography and examined the differences in dentine volume removed, canal straightening, the proportion of the unchanged area and canal transportation. Quantitative analysis revealed that instrumentation increased in canal volume ranging between 0.081 and $1.866{\;}\textrm{mm}^3$. On average, the large apical preparation produced by ProTaper demonstrated smaller proportions of unchanged surface areas compared to the two other instruments in small canals. But in large canals like maxillary central incisor, the preparation of ProTaper instruments was not enough. ProTaper instrument was tended to increase more in canal volume as compared with the other two instruments but unchanged area was no significant difference. These results showed that three instruments had similar preparation ability and micro computed tomography in combination with the coated wall of root canal using silver paste is a nondestructive and valuable tool to study root canal geometry and changes after preparations in detail.

• Restorative Dentistry and Endodontics
• /
• 제16권1호
• /
• pp.167-180
• /
• 1991

The purpose of theis study was to evaluate the effectiveness of ultrasonic instrumentation in removing debris and smear layer from the root canal walls. 54 extracted, permanent single rooted teeth were randomly divided into 6 groups of 9 teeth. After canal preparation, the teeth were longitudinally sectioned. The sepcimens were then naturally dried for 2 days, given a maximun thickness gold coating, and examined under the SEM (JSM-35C type, JAPAN). Photographs of all specimens were then taken of the middle and the apical third of the root canal wall. The results were as follows: 1. In all groups, debris and the smear layer were not completely removed from the canal wall 2. There were no significant differences between at the apical third and at the middle third in removing debris and the smear layer in all groups. 3. There were no significant difference between the step - back group and the ultrasound group in removing debris and smear layer. 4. In general, the step - back/ultrasonund groups showed greater canal debridement than the step - back group or ultrasound group. 5. The step - back/ultrasound group with a No. 25 file for 3 min. showed significantly greater canal debridement than the step-back group (p<0.05), or the other step - back/ultrasound groups(p<0.05).

• Restorative Dentistry and Endodontics
• /
• 제24권3호
• /
• pp.503-510
• /
• 1999

The purpose of this study was to evaluate the amount of transportation of original canal, zip formation, permanent deformation and fracture of instruments after canal enlargement. In this study, the 60 resin blocks that have curved canals were randomly divided into 3 experimental groups with 20 teeth each according to instrument types and filling methods for canal enlargement. The curved canals of each experimental groups were enlarged to No 40 ISO size with the K-flexo stainless steel file (Group 1), Engine-driven Ni-Ti Profile new series(Group 2) and Engine-driven Ni-Ti Quantec 2000 series(Group 3) according to the manufacturer's recommendation. Pre- and postoperative X-rays were taken at same position and the films were scanned and the canal images were traced to determine the canal curvature according to the method of Schneider. The amount of reduction in canal curvature were calculated between pre- and postoperative X-rays. In addition to zip formation, permanent deformation and fracture of instruments were examined after canal enlargement. The results were as follows : 1. All experimental groups showed some loss of canal curvature after instrumentation. There was a significant change in curvature between before and after instrumentation in each group(p<0.001). 2. Engine-driven Ni-Ti instrumentations resulted in an average loss of curvature of 2.36 degrees for Profile new series, 3.43 degrees for Quantec series, and hand instrumentation showed an average loss of curvature of 6.48 degrees for K-flexo file. There was a statistical significant difference between hand instrumentation and engine-driven Ni-Ti instrumentations(p<0.05). But there was no statistical difference between Profile new series and Quantec series. 3. There were many apical zip formations in group 1(Hand instrumentation). But there were no apical zip formations in group 2,3(Engine-driven Ni-Ti instrumentation). 4. The instrument deformation occured 9 cases in group 1(K-flexo file), 2 cases in group 2(Profile new series) and 3 cases in group 3(Quantec) after instrumentation. And the instrument fracture occured 1 case in each group. The results showed that the engine-driven Ni-Ti instruments, if we use carefully according to manufacturer's recommendations, can be use effectively for instrumenting the curved root canals in case of the MAF was over size 40.