Root surface temperature rises in vitro during root canal obturation using hybrid and microseal techniques

The aim of this in vitro study was to measure the temperature rise on the outer surface of roots during filling with hybrid technique and Microseal. Twenty extracted human maxillary and mandibular premolars with a single canal were randomly divided into two groups of 10 teeth each. In the first group, the teeth were filled with hybrid technique (thermomechanical compaction with Engine Plugger used following lateral condensation of the apical part of the canal), the second group was filled using Microseal. After root canal obturation the filling material was removed and the obturation procedure was repeated. A total of 20 obturations in each group were performed. Temperature changes were measured using a thermal imaging camera. The temperature of certain regions of the mesial surface was analyzed and the highest temperature values were recorded. Statistical analysis was performed using the Mann-Whitney U test. The mean increase of temperature during the hybrid technique with Engine Plugger was 23.8 degrees C, while during Microseal it was significantly lower (p = 0.000001) at 5.5 degrees C. The temperature rise generated by Microseal was below the critical level and should not damage supporting structures, however, the hybrid technique generated a relatively high temperature rise that may cause periodontal tissue damage.     

Root surface temperature rises in vitro during root canal obturation with thermoplasticized gutta-percha on a carrier or by injection

The aim of this in vitro study was to measure the temperature rise on the outer root surfaces of teeth during four different root canal obturation techniques. Sixty extracted human maxillary and mandibular premolars with a single canal were used. After root canal cleaning and shaping, the teeth were randomly divided into four groups of 15 teeth each and obturated with Thermafil obturators or Soft-Core obturators using Ultrafil or Trifecta low-temperature thermoplasticized gutta-percha techniques. Temperature changes on the external mesial root surfaces were measured using a thermal imaging camera. Lower temperature rises were found for Ultrafil and Trifecta techniques (2.14 degrees C and 2.03 degrees C, respectively) than for Thermafil and Soft-Core techniques (3.87 degrees C and 3.67 degrees C, respectively). These findings suggest that solid core gutta-percha combined with low-temperature injectable gutta-percha obturation techniques may impose less risk for thermal damage to the surrounding periradicular tissues.     

改进的连续波热牙胶根充法应用于老年人根管充填的临床评价

目的：评价老年人根管充填应用改进的连续波热牙胶根充法的充填质量和效率。方法：213名需要根管治疗的老年口腔患者,共计238颗患牙,按照根管充填方法的不同分为热牙胶组和冷侧压组,并对两组间根管充填恰填率、侧支根管充填情况、根充所用时间、术中疼痛四方面进行对比分析。结果：改进的连续波热牙胶组根管恰填率高达89．92％,而冷侧压组仅为79．82％,热牙胶组优势明显;另外在侧支根管充填情况和根充所用时间的对比中,热牙胶组依然强于冷牙胶组（P〈0．05）;两组术中疼痛并没有差别（胗0．05）。结论：改进的连续波热牙胶根管充填法应用于老年口腔患者优点突出,易于接受,能有效提高老年人根管治疗的质量和效率。     

高温注射式热牙胶充填根管时牙根表面温度的变化

目的:评估Obtura Ⅱ热牙胶系统牙胶加热温度在160、180、200 ℃进行根管充填时根管外表面温度的变化是否会对牙周组织造成热损伤,及使用封闭剂对温度变化的影响.方法:42颗离体单根管恒牙根管预备后,用Obtura Ⅱ热牙胶系统以不同温度加热牙胶及是否使用封闭剂分组充填根管.测定根管充填前后根管外表面温度的变化.结果:在3种温度设定下充填时,根管外表面温度的升高值平均都未超过10℃阈值.充填前使用封闭剂对根管外表面温度的升高无论是减少还是增加都未超过1℃,均无统计学意义(P＞0.05).结论:Obtura Ⅱ热牙胶系统在160、180℃的工作温度下进行根管充填时,不会对牙周组织造成热损伤,但200℃的温度设定需谨慎选择;使用封闭剂对抑制根管表面温度的升高无明显影响.     

In vitro infrared thermographic assessment of root surface temperature rises during thermafil retreatment using system B

The purpose of this in vitro study was to measure the temperature rise on the outer root surface during retreatment of Thermafil using the System B HeatSource. Twenty extracted human maxillary premolars were filled with Thermafil with plastic carriers and divided into two groups of 10 teeth each. In group 1, Thermafil obturators were retrieved using System B HeatSource fitted with a medium plugger at a temperature of 225 degrees C. The plugger was placed first on the buccal, then on the lingual of the plastic carrier for 5 s each. This melted the gutta-percha and softened the plastic carrier. In group 2, Thermafil obturators were retrieved in the same manner except that the heated plugger was placed for 8 s. The temperature changes on the outer root surfaces were recorded using a thermal imaging camera. Thermafil retreatment in vitro using a System B HeatSource causes temperature rises ranging from 26.7 degrees C to 46.0 degrees C. This finding could possibly have implications for creating injury of the periodontal tissues.     

Root canal obturation by ultrasonic condensation of gutta-percha. Part II: an in vitro investigation of the quality of obturation

AIM: To compare the quality of root canal obturation using ultrasonic or cold condensation of gutta-percha and to determine the effect of power setting and activation time on the quality of obturation using the former technique. METHODOLOGY: An extracted human maxillary canine was used in an in vitro split tooth model to allow repeated obturation of the same root canal system using an ultrasonic device to thermocompact gutta-percha without sealer. After each obturation, the root filling was removed from the tooth to allow evaluation of its quality and for the tooth to be re-obturated. The influence of combinations (n = 10 per combination) of power setting (1, 3, 5) and activation times (4, 10, 15 s) was tested on the quality of root filling, assessed by measuring the voids within the body of the root filling as well as at the surface. Image analysis was used to quantify the voids within the body of the root filling. Cold lateral condensation of gutta-percha served as a control. RESULTS: Both surface and cross-sectional analyses revealed that different power setting and activation time combinations produced significantly fewer voids than cold lateral condensation (P < 0.05) at the apical, mid-root and coronal levels. CONCLUSIONS: Taking surface and cross-sectional analysis together only power setting 5 and activation times of 10 and 15 s consistently produced ultrasonically thermocompacted root canal fillings with fewer voids than cold lateral condensation without sealer.     

Measurements of the root surface temperature during thermo-mechanical root canal filling in vitro

Summary. The temperature rise at the root surface during thermo-mechanical root canal obturation was studied in vitro in 15 human teeth. The mean temperature elevation at a point 5 mm coronal to the apex was found to be 35°C. The impact of the results on the periodontal tissues during conditions in vivo are discussed.     

A comparison of thermocouple and infrared thermographic analysis of temperature rise on the root surface during the continuous wave of condensation technique

AIM: This study was designed to use two methods of temperature measurement to analyse and quantify the in vitro root surface temperature changes during the initial stage of the continuous wave technique of obturation of 17 single-rooted premolar teeth with standard canal preparations. METHODOLOGY: A model was designed to allow simultaneous temperature measurement with both thermocouples and an infrared thermal imaging system. Two thermocouples were placed on the root surface, one coronally and the other near the root apex. A series of thermal images were recorded by an infrared thermal imaging camera during the downpack procedure. RESULTS: The mean temperature rises on the root surface, as measured by the two thermocouples, averaged 13.9 degrees C over the period of study, whilst the infrared thermal imaging system measured an average rise of 28.4 degrees C at the same sites. Temperatures at the more apical point were higher than those measured coronally. After the first wave of condensation, the second activation of the plugger in the canal prior to its removal always resulted in a secondary rise in temperature. The thermal imaging system detected areas of greater temperature change distant from the two selected thermocouple sites. CONCLUSIONS: The continuous wave technique of obturation may result in high temperatures on the external root surface. Infrared thermography is a useful device for mapping patterns of temperature change over a large area.     

Evaluation of temperature rise on the outer surface of teeth during root canal obturation techniques

The heat generated at the apical 2 mm of the outer root surface of extracted human canine teeth during three obturation procedures was measured. The rise in temperature was found to be less when a sealer was used in all obturation techniques. Temperatures as high as 44.02 degrees C were recorded with warm gutta-percha with no sealer, and the lowest temperature rise occurred with a thermoplasticized gutta-percha technique with a sealer. The thickness of the remaining dentin and cementum after cleaning and shaping were found to have no effect in reducing temperature rise. The results of this investigation indicated that temperature rise on the outer surface of the root as a result of heat-generating obturation procedures is negligible and will not have an effect on the supporting attachment apparatus.     

Changes in root surface temperatures with in vitro use of the system B HeatSource

The purpose of this study was to measure root surface temperatures while using the System B HeatSource at various temperature settings. A split-tooth model of a human maxillary central incisor was prepared with 10 thermocouples to record root surface temperatures at 1-mm increments from the root apex. A System B HeatSource model 1005 was used to warm and compact gutta-percha to within 3 mm of the working length using the Buchanan technique. Twenty obturations were recorded at each of the following temperature settings: 250 degrees, 300 degrees, 350 degrees, 400 degrees, 450 degrees, 500 degrees, 550 degrees, and 600 degrees C. Examination of the mean temperatures recorded for each position and at each temperature setting revealed that the thermocouple 5 mm from the apex (T5) detected the highest increases in root surface temperatures. Only this site exceeded the 10 degrees C rise in temperature for one full minute that could cause damage to the supporting structures. The range of instantaneous temperatures at this site was 8.85 to 12.06 degrees C, with a mean of 10.62 +/- 0.93 degrees C. The results of this in vitro study indicate that any temperature setting of the System B HeatSource at or above 250 degrees C has the potential to cause the root surface temperature to rise 10 degrees C. Whether this occurs in vivo or if it does is maintained long enough to cause any tissue damage remains to be determined.     

Heat transmission to the outer surface of the tooth during the thermo-mechanical compaction technique of root canal obturation

Summary. The heat generated at the outer surface of human canine teeth during the technique of obturation of the root canal by thermo-mechanical compaction of gutta-percha, both with and without a proprietary root sealer, was measured.
The rise in temperature was recorded at a point on the apical and central thirds of the outer surface of each specimen. The temperature rise was greater at the central area of the root than apically but the use of a sealer gave no statiscally significant difference in temperature. The thickness of dentine did not influence the results. Rises in temperature up to 27°C were recorde.
Three compactors fractured during use. The findings of this investigation would indicate the need for caution and further study before complete acceptance of the technique. The speed and efficacy of the procedure when used in straight canals with closed apices, however, is not in qustion.     

Comparison of the obturation density of cold lateral compaction versus warm vertical compaction using the continuous wave of condensation technique

The purpose of this in vitro study was to compare quantitatively the density of standard cold lateral gutta-percha compaction and warm vertical compaction by using the continuous wave of condensation technique. Forty transparent acrylic blocks with 30-degree, curved root canals were instrumented using Gates Glidden burs and Profile 0.06 taper rotary nickel-titanium files in a crown-down manner. The blocks were weighed and randomly assigned to two evenly distributed groups. Group A was obturated with the cold lateral-compaction technique using medium-fine, gutta-percha accessory points until the canal was completely filled. Group B was obturated with the continuous wave of condensation technique until the canal was completely filled. The blocks were weighed again after obturation. Data were analyzed using a two-sample t test at the 5% significance level. Results demonstrated that the continuous wave of condensation technique resulted in a significantly greater density compared with cold lateral compaction. Warm vertical compaction using the continuous wave of condensation technique in acrylic blocks resulted in a greater gutta-percha fill by weight compared with standard cold lateral compaction.     

Iatrogenic risks during the obturation of the root canal system

A hermetic seal is the main goal of obturation of the root canal system. For that purpose guttapercha still remains the filling material of choice. Most filling techniques use plasticized guttapercha and a condensation technique to fulfil the requirements of hermetic seal. The heat to plasticize and the forces applied to condense that material may have an influence on the periodontal ligament and/or the remaining tooth structure. Furthermore can overfilling of guttapercha and more likely the sealer, affect the periodontal tissue. Although rare, mandibular nerve damage and adverse effects on the sinus maxillaris can be the result of inadequate treatment.     

Outcome of root canal obturation by warm gutta-percha versus cold lateral condensation: a meta-analysis

The purpose of this study was to evaluate clinical outcome differences of root canal obturation by warm gutta-percha (GP) or cold lateral condensation (CLC) through a systematic review and meta-analysis. There were 10 clinical studies evaluated. Postoperative pain, long-term outcomes, obturation quality, and overextension were the characteristics investigated. The results suggest that the two obturation techniques are not significantly different except in overextention. The relative risk (RR) value of warm GP versus CLC and 95% confidence interval (CI) of the first three criteria were 1.10 (0.71, 1.71), 0.78 (0.58, 1.05), and 1.31 (0.98, 1.76), respectively. Overextension was more likely to occur in the warm GP obturation group in comparison with the CLC group. The RR value and 95% CI were 1.98 (1.33, 2.93). In conclusion, warm GP obturation demonstrated a higher rate of overextension than CLC. Postoperative pain prevalence, long-term outcomes, and obturation quality were similar between the two groups.     

AH plus和iRoot SP用于热牙胶充填的根尖封闭性能研究

目的 利用体外模型比较热牙胶充填时,2种根管封闭剂AH plus和iRoot SP的根尖微渗漏情况,评估两种材料的根尖封闭性能.方法 离体牙30颗,根管预备后,随机分为2个实验组A和B,1个阳性对照组(C)和1个阴性对照组(D).其中实验组每组10颗离体牙,对照组每组5颗离体牙.分别选用AH plus(A组)和iRoo...     

Three-dimensional obturation of the root canal using injection-molded, thermoplasticized dental gutta-percha.

The technique of injection-molding was applied to thermoplasticized dental gutta percha in vitro. Teeth were biochemically instrumented before obturation of the root canal space. Thermoplasticized gutta percha was injected, with and without the use of a sealer, using a pressure syringe. The quality of the seal was assessed by dye penetration studies. The findings showed that the injection-molding technique leads to a seal comparable to that of conventional approaches. The technique holds promise for in vivo use.     

System-B充填技术对模拟侧支根管充填效果的体外评价

目的:研究System-B连续波垂直加压充填技术对不同部位、不同直径侧支根管的充填情况.方法:选取人类单根管离体牙40颗,随机分为2组.根管预备后,在距根尖3mm、6mm、9mm处制备8#及15#K锉直径的人工侧支根管,分别用System-B连续波垂直加压充填技术和传统冷牙胶侧压充填法进行充填.制备成透明牙后,在体视显微镜下观察侧支根管的充填情况,采用SPSS13.0软件包对2组的充填效果进行比较.结果:System-B连续波垂直加压充填技术组和冷牙胶侧方加压充填技术组对侧支根管的充填率分别是85.00%和49.17%(P<0.05).System-B连续波垂直加压充填技术组对距根尖孔6mm、9mm处的侧支根管充填率及进入侧支根管充填物长度均优于3mm处(P<0.05),而6mm与9mm处的侧支充填,无论充填率或是充填长度,两者均无显著性差异(P>0.05);侧支根管充填的充填长度显示,直径较大的15#K锉组优于直径较小的8#K锉组(P<0.05).结论:System-B连续波垂直加压充填技术对侧支根管的充填效果优于冷牙胶侧压充填技术,其对不同部位及不同直径的侧支根管的充填效果也有差别.     

采用葡萄糖定量分析法评价连续波热牙胶充填技术的根管封闭性能的研究

目的采用葡萄糖定量法检测根管微渗漏模型评价连续波热牙胶充填技术的根管封闭性。方法选取30颗离体单直根管下颌前磨牙,机用镍钛ProTaper根管预备后随机分成连续波热牙胶充填组和冷牙胶侧方加压充填组(每组10例)和2个对照组(阳性对照和阴性对照各5例),根充后建立微渗漏葡萄糖定量分析法模型,通过在第1、4、7、20天用葡萄糖氧化酶法检测从冠方向根方渗出的葡萄糖的量,观察其微渗漏情况。结果第1天2组微渗漏值无显著性差异(P>0.05),第4、7天,连续波充填组的微渗漏小于冷侧压充填组(P<0.05),第20天时,2组无显著性差异(P>0.05)。结论尽管冷侧压充填发生微渗漏快于连续波充填,但是两者的根管封闭性无显著差异。     

In vitro infrared thermographic assessment of root surface temperatures generated by high-temperature thermoplasticized injectable gutta-percha obturation technique

The aim of this in vitro study was to measure the temperature rises on the outer surface of roots produced by high-temperature thermoplasticized injectable gutta-percha technique. Thirty extracted human teeth with a single canal (15 maxillary central incisors and 15 mandibular central incisors) were used in this study. After root canal cleaning and shaping, the teeth were obturated with the injected gutta-percha heated to 160 degrees C (Obtura II). Temperature changes on the whole mesial outer surface of the roots was measured using an infrared thermal imaging camera. It showed that the use of gutta-percha heated to 160 degrees C to fill the maxillary central incisors and mandibular central incisors resulted in the rises of the root surface temperature by 8.5 degrees C and 22.1 degrees C, respectively. In conclusion, the injection of the gutta-percha heated to 160 degrees C into the root canal of maxillary central incisors produces temperature on the outer root surfaces below the theoretical critical level and, therefore, should not cause damage to supporting periradicular tissues. The injection of gutta-percha into the root canal space of the mandibular central incisors in vitro, resulted in an elevation of the root surface temperature by more than 10 degrees C.