三种充填技术根管封闭能力的研究

目的:利用葡萄糖定量法检测根管微渗漏模型,评价侧向加压充填技术、垂直加压充填技术及固核载体充填技术对根管微渗漏的影响.方法:选取71颗直根管上前牙,根管预备后随机分为7组,A组(14颗)用热牙胶垂直加压加AH Plus充填;B组(8颗)仅用热牙胶垂直加压充填;C组(13颗)用侧方加压加AH Plus充填;D组(8颗)仅用侧方加压充填技术;E组(11颗)用Thermafil加AH Plus充填;F组(7颗)仅用Thermafil充填;G组(10颗)为阴性对照组,用粘蜡充填根管.牙根外表面、根管口及根尖孔处涂二层指甲油.于第7 d、14 d、21 d、28 d用葡萄糖氧化酶法检测从冠方向根方漏出的葡萄糖量.结果:采用重复测量方差分析,发现第7 d、14 d、21 d、28 d A、C组及C、E组微渗漏值有显著性差异(P＜0.001),但A、E组无显著性差异(P＞0.05).各时间点C、D组比较有显著性差异(P＜0.001),但A、B组与E、F组比较无显著性差异(P＞0.05).第7 d、14 d及第21 d、28 d各组内比较无显著性差异(P＞0.05),但各组第14 d与第21 d比较有显著性差异(P＜0.05).结论:侧方加压充填技术封闭根管的能力优于垂直加压充填技术及固核载体充填技术,而后两种充填技术封闭根管的能力相当.     

Leakage evaluation of three different root canal obturation techniques using electrochemical evaluation and dye penetration evaluation methods

The aim of this study was to compare the apical sealing ability of three different obturation techniques using an electrochemical evaluation and evaluating dye penetration. One hundred and thirty-two maxillary anterior teeth were randomly divided into six groups. There were 20 teeth in each group. The teeth were obturated as follows: Groups 1 and 4 with Thermafil, Groups 2 and 5 with System B, and Groups 3 and 6 with cold lateral condensation (CLC). The apical leakage in these groups was evaluated using an electrochemical method for Groups 1, 2, 3 and a dye penetration method for Groups 4, 5 and 6. In both methods, the lowest mean leakage values were observed for Thermafil and the highest were observed for the CLC groups. The difference between Thermafil and CLC was statistically significant (P < 0.05). In both groups, System B fillings showed moderate leakage and the difference was not significant with Thermafil and CLC groups.     

Subantimicrobial dose doxycycline as adjunctive treatment for periodontitis. A review

BACKGROUND: Subantimicrobial dose doxycycline (SDD--20 mg doxycycline twice daily) is indicated as an adjunctive treatment for periodontitis. Doxycycline downregulates the activity of matrix metalloproteinases (MMPs), key destructive enzymes in periodontal disease. Current understanding of periodontal pathogenesis suggests that MMPs play a major role in the destruction of periodontal tissues, leading to the clinical signs of periodontitis. Research supports that downregulation of MMPs by SDD confers benefit to patients with periodontitis. METHOD: We review the clinical, microbiological and safety data relating to the use of SDD in patients with periodontitis, and consider the historical events that led to the development of adjunctive SDD as a treatment for periodontitis. RESULTS: Studies have shown that SDD, when prescribed as an adjunct to scaling and root planing (SRP), results in statistically and clinically significant gains in clinical attachment levels and reductions in probing depths over and above those that are achieved by SRP alone. SRP must be thorough and performed to the highest standard to maximise the benefits of adjunctive SDD. SDD does not result in antibacterial effects, or lead to the development of resistant strains or the acquisition of multiantibiotic resistance. The frequency of adverse events is low, and does not differ significantly from placebo. CONCLUSIONS: Adjunctive SDD confers clinical benefit to patients with periodontitis. A comprehensive treatment strategy is suggested, involving patient education and motivation, reduction of the bacterial burden by SRP, host response modulation with SDD, and periodontal risk factor modification.     

新型纳米羟基磷灰石(n-HA)糊剂封闭根尖性能及其对病原菌抗菌活性的体外实验

目的：研究新型纳米羟基磷灰石根管充填糊剂（n-HA）、AH-Plus根管封闭剂的根尖封闭性能以及二者对感染根管优势菌牙龈卟啉单胞菌（Porphyromonas gingivalis,Pg）、具核梭杆菌（Fusobacteria nu-cleatum,Fn）、中间普氏菌（Prevotalla intermedius,Pi）生长的影响。方法：实验一34个离体单根管牙随机分为4组,用镍钛旋转器械Protaper预备根管,阳性对照（2个）、阴性对照（2个）、2个实验组（各15个）,分别用新型n-HA、AH-plus根充糊剂加牙胶尖以冷侧压法根充恰填,染料渗入法检查根尖微渗漏。实验二选用Pg、Fn、Pi作为实验菌株,常规打孔法测定新型纳米羟基磷灰石根管充填料、AH-Plus根管封闭剂的抑菌效果。结果：所有根充糊剂充填后根尖部位均有微渗漏,AH-plus组的微渗漏值低于n-HA组,2组结果间无统计学意义（P〉0.05）。n-HA与AH-Plus糊剂对Pg、Fn、Pi均有一定的抑菌作用,但n-HA的抑菌作用明显强于AH-Plus。结论：2种根充糊剂充填后都不能完全封闭根尖孔,AH-plus根充糊剂的根尖封闭性优于n-HA组。n-HA根充糊剂具有较理想的抑菌效果。     

Comparison of cold lateral condensation and a warm multiphase gutta-percha technique for obturating curved root canals

AIM: The aim of this project was to evaluate and compare the radiographic quality and sealability of root fillings in extracted human teeth using lateral condensation of gutta-percha or multiphase gutta-percha obturation (Alphaseal). METHODOLOGY: A total of 108 freshly extracted human, mature single-rooted teeth were divided into two identical groups of 54 teeth on the basis of root canal shape. The canals were prepared to a minimum 0.055 taper and enlarged to size 35 at the apex. All root canals were flushed with 17% EDTA solution and 2.5% NaOCl to remove the dentinal smear layer. The canals of one group were obturated using cold lateral condensation of gutta-percha and the canals of the other group were filled using a warm multiphase gutta-percha obturation technique. The extrusion of sealer and/or gutta-percha through the apex of the teeth was recorded using a simple yes/no scheme. The sealability of each technique was assessed by a dye penetration method. The radiographic quality of obturation was determined for each canal using a four-point scale. RESULTS: Root canals filled by multiphase obturation had significantly more extrusion of sealer (P < 0.001) and gutta-percha (P < 0.001) than canals filled by lateral condensation. Canals filled by multiphase gutta-percha obturation had significantly less apical dye leakage than those obturated by lateral condensation (P < 0.05). Lateral condensation achieved significantly better scores for radiographic quality than multiphase obturation from the bucco-lingual view (P < 0.01). CONCLUSIONS: Under laboratory conditions multiphase gutta-percha had better sealability but poorer radiographic quality than lateral condensation.     

Comparative study of retreatment of Thermafil and lateral condensation endodontic fillings

The aim of the present study was to evaluate the possibility of retreating teeth obturated with: (i) Thermafil with plastic carrier, (ii) Thermafil with metallic carrier and (iii) laterally condensed gutta-percha. The following aspects were analysed: removal of obturation, time required for removal, remaining filling material and apical extrusion during reinstrumentation. Thirty human teeth with a single canal were instrumented up to a size 45 K-type file, divided into three groups of 10 teeth each and obturated with Thermafil with plastic carrier (group 1), Thermafil with metallic carrier (group 2), and laterally condensed gutta-percha (group 3) with AH26 as the sealer. Reinstrumentation was performed manually after 30 days storage using Hedstroem files and xylene as a solvent. The average time needed to remove the obturation was 12 min 1 s for group 1, 14 min 36 s for group 2 and 11 min 26 s for group 3. Although no statistically significant differences were observed between groups 1 and 2, and 1 and 3 ( P > 0.05), the differences between groups 2 and 3 were significant ( P < 0.05). The amount of remaining filling material was significantly higher in group 2 when compared with groups 1 and 2 ( P < 0.01). Although the lowest incidence of apical extrusion during reinstrumentation was found in group 3, the differences among groups were not statistically significant.     

Determination of pH and calcium ion release provided by pure and calcium hydroxide-containing AHPlus

AIM: To compare in vitro the pH and calcium ion release provided by pure and calcium hydroxide-containing AHPlus. METHOD: Pure and modified AHPlus, the latter containing 5 and 10% (w/w) calcium hydroxide added during spatulation, were used. The material was spatulated and stored in 10 tubes that were 1 cm long and 1.5 mm in diameter, and then immersed in 20 mL deionized water before the materials had set. Ten tubes with zinc oxide and eugenol were used as controls. Four millilitres of water was removed from the flasks after 24 and 48 h, and after 7, 14 and 30 days, and pH and calcium release were measured with a pH meter and by atomic absorption spectrophotometry, respectively. The results obtained at each time point were compared statistically. RESULTS: A more alkaline pH for AHPlus supplemented with 5 and 10% calcium hydroxide was recorded when compared to pure AHPlus; there were significant differences at 14 and 30 days (P<0.05). The results of calcium ion release showed no significant difference between pure AHPlus and zinc oxide plus eugenol (P>0.05). The comparisons between the AHPlus containing 10% calcium hydroxide with AHPlus containing 5% calcium hydroxide, pure AHPlus, zinc oxide plus eugenol demonstrated significant differences (P<0.05) at all periods. The comparisons between AHPlus containing 5% calcium hydroxide with pure AHPlus and zinc oxide plus eugenol demonstrated significant differences (P<0.05) at all periods of evaluation. CONCLUSIONS: The addition of 5 and 10% calcium hydroxide to AHPlus cement favoured a more alkaline pH and greater calcium ion release.     

Resistance to fracture of restored endodontically treated teeth

Abstract Endodontically treated teeth were restored by 8 different methods. Copper rings were filled with commercial hard setting cement and the teeth were placed into the cement to the level of the cemento-enamel junction. The teeth were grouped according to restorative methods, mounted in an Instron T.T. machine and subjected to a slowly increasing compressive force until fracture occurred. The force of fracture for each tooth was recorded and the results in the various groups compared. All teeth fractured in a similar manner, irrespective of restorative method used. Preparation of a post space in the roots significantly weakened the teeth. Cementation of a steel parapost with zinc oxyphosphate cement did not significantly strengthen the teeth. Filling the post space and the access cavity with a composite resin following acid etching of the root canal and cavity walls strengthened the teeth more than other methods used to restore them. This finding may be of clinical importance, for instance in the restoration of endodontically treated young teeth with incomplete root formation and wide root canals.     

Prognosis of luxated non-vital maxillary incisors treated with calcium hydroxide and filled with gutta-percha. A retrospective clinical study

Abstract A material of 885 luxated, non-vital incisors was evaluated radiographically with respect to healing of periodontal tissues including inflammatory root resorption and occurrence of ankylosis and cervical root fractures. The results were assessed after completion of calcium hydroxide treatment and 4 years after filling of the root canal with gutta-percha. After treatment with calcium hydroxide, periapical healing occurred in 95% of the teeth. Four years after filling with gutta-percha, periapical healing was present in 91% of the teeth. In the remaining teeth, recurrent or persistent periapical radiolucency was more frequent in overfilled than adequately filled teeth (P = 0.0001). There was no difference between immature and mature teeth. Inflammatory root resorption healed in 192 of 197 teeth (97%); in 5 teeth it developed into ankylosis. Ankylosis occurred in 13 teeth, all of which were intruded into the alveolar bone at the time of injury. The frequency of cervical root fractures was markedly higher in immature than mature teeth (P>0.0001). Among immature teeth, the frequency of fractures was dependent on the stage of root development [x²= 31,6) and ranged from 77% in teeth with the least to 28% in teeth with the most developed roots. The frequency of fractures was also related to the defects after healing of inflammatory root resorption in the cervical area of the root, significant at P< 0.0001.