Effect of access cavity location and design on degree and distribution of instrumented root canal surface in maxillary anterior teeth

AIM: The null hypothesis tested in this study was that in single-rooted anterior teeth with simple root canal anatomy, different access cavity designs ('lingual cingulum', 'lingual conventional', 'incisal straight-line') do not influence the ability of endodontic files to plane the walls of the root canals. METHODOLOGY: Thirty extracted human maxillary anterior teeth were divided randomly into three groups for each access cavity. The access cavities were prepared according to predefined criteria and the roots embedded in individual polyvinyl-siloxane putty matrices. The matrices allowed these teeth to be split into buccal and palatal halves and to be reassembled. The split teeth enabled removal of pulpal remnants from the root canal system and the walls to be stained with an even layer of permanent black ink. Once dried, the split roots were reassembled in the putty matrices and a step-back filing technique was used to prepare the canals with water irrigation. The canal walls were examined for residual ink staining and scored by three independent assessors using an index devised for the purpose. RESULTS: There was good agreement between the assessors. None of the access cavities allowed file contact with the entire root canal wall. The overall (palatal and buccal sections) scores showed significant differences (P < 0.01) between the access cavity groups in the extent to which the canal walls could be filed. The straight-line incisal access cavity had the greatest proportion of instrumented root canal surface. The lingual cingulum access cavity was the worst in this respect. The differences in residual ink scores between the access cavity types were significant for the buccal halves (P < 0.01) but not for the palatal halves (P > 0.05). CONCLUSIONS: The null hypothesis was proven. Regardless of access cavity design, mechanical preparation did not allow instrumentation of the entire root canal wall. Straight-line access allowed the greatest proportion of the root canal wall to be instrumented and the lingual cingulum access the least.     

Sealing ability of thermoplasticized gutta-percha in root canal obturation using a sectional vs. a single-phase technique

Abstract Properly prepared straight root canals of freshly extracted maxillary canines and central incisors were used to evaluate the sealing ability of the sectional thermoplasticized gutta-percha obturation technique, with or without sealer and the single-phase thermoplasticized gutta-percha filling technique. The teeth were divided into 3 groups (A, B, C) of 20 teeth and were obturated using the 3 thermoplasticized gutta-percha techniques. Group A: single phase with sealer; group B: sectional technique without sealer; and group C: sectional technique with sealer. The obturated teeth were immersed in India ink for 3 days followed by clearing procedures. The teeth were then examined under a stereo microscope and the linear leakage was recorded. Statistical unpaired Student's t-tests showed significantly less dye penetration in teeth obturated using the sectional technique with sealer (group C) than in teeth obturated with the single-phase technique with sealer (group A) or the sectional technique without sealer (group B).     

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.     

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.     

产前应用地塞米松促胎肺成熟对先兆早产孕妇血糖的影响研究

背景　早产是一种严重而常见的妊娠并发症,早产儿因身体各系统器官发育不成熟而存活率低,会造成沉重的家庭社会负担。产前使用糖皮质激素是国际公认的促胎肺成熟、使新生儿获益的标准措施,但地塞米松的治疗对母体血糖有一定的不良影响,且母体血糖随地塞米松血药浓度峰值变化的机制尚不清楚。目的　探究产前应用地塞米松促胎肺成熟对先兆早产孕妇血糖的影响。方法　选取2018年10月-2020年2月佛山市妇幼保健院收治的因先兆早产需住院行地塞米松促胎肺成熟治疗且符合纳入标准的63例孕妇为研究对象,根据孕24~28周的口服葡萄糖耐量试验（OGTT）结果分为妊娠期糖尿病（GDM）组和非GDM组。两组孕妇入院后均接受统一的促胎肺成熟方案：地塞米松肌肉注射,6 mg/次,1次/12 h,共4次。使用美敦力MINIMED动态血糖监测系统监测两组孕妇每次注射地塞米松前1 h和注射后3 h的血糖。比较两组孕妇第1、2、3、4次地塞米松注射前1 h和注射后3 h血糖,4次地塞米松注射后血药浓度峰值前后1 h血糖,并绘制相应的血糖随时间变化趋势图。结果　最终完成研究55例,其中GDM组16例,非GDM组39例。GDM组和非GDM组孕妇第1、2、3、4次地塞米松注射前1 h和注射后3 h血糖比较,差异均无统计学意义（P>0.05）。GDM组孕妇第2、3、4次地塞米松注射前1 h血糖均高于第1次（P<0.05）;GDM组孕妇第1、2、3、4次地塞米松注射后3 h血糖比较,差异无统计学意义（P>0.05）。非GDM组孕妇第2、3次地塞米松注射前1 h血糖均高于第1次（P<0.05）;非GDM组孕妇第2、3、4次地塞米松注射后3 h血糖均高于第1次（P<0.05）。GDM组与非GDM组孕妇第1、2、3、4次地塞米松注射后血药浓度峰值前后1 h血糖比较,差异均无统计学意义（P>0.05）。接受地塞米松注射后3 h内,非GDM孕妇血糖均在参考范围内波动,无明显规律趋势;GDM组孕妇血糖波动范围较大,且4次地塞米松注射120 min后血糖逐渐升高。结论　单胎孕妇注射地塞米松2 h内,其血糖可能不受地塞米松血药浓度峰值影响;地塞米松升高血糖的作用时间是在注射后3 h,4次地塞米松注射对血糖的升高无累积效应。接受地塞米松注射后3 h内,非GDM孕妇血糖均在参考范围内波动,无明显规律趋势;GDM组孕妇血糖波动范围较大,且4次地塞米松注射120 min后血糖逐渐升高。     

导泻排毒液清除化道毒物治疗急性中毒的实验研究

目的：探讨导泻排毒液通过清除消化道残留毒物而治疗急性中毒的机制。方法：观察导泻排毒液对小白鼠胃排空的影响;对小鼠白鼠肠功能的;对家兔离体肠平滑肌的影响。对大白鼠口服苯巴比妥血药浓度的影响。结果：导泻降低小白鼠胃中甲基残留率,有促进胃排空作用,能提高小白鼠肠道炎末推进率,有增强肠道推进功能作用。能使家兔离体肠客收缩幅度增大,蠕皮明显加深,肠管肌张力明显增加,能降低大白鼠口服苯巴比妥血药浓度。与对照组     

Conservative surgical and microsurgical techniques for the management of dental implants that impinge on the inferior alveolar nerve

Loss of sensation in the lip after insertion of an implant is annoying. The aim of this paper was to describe two techniques for management of osseointegrated dental implants that impinge on the mandibular nerve, the purpose of which is to improve sensation without unscrewing the dental implant.     

The Effect of Photodynamic Therapy in Root Canal Disinfection: A Systematic Review

Introduction

Effective root canal disinfection is a fundamental component of successful root canal treatment. Photodynamic therapy (PDT) has been proposed as a new adjunctive method for additional disinfection of the root canal system with the possibility of improved treatment outcomes. The aim of this systematic review was to investigate the effect of PDT on bacterial load reduction during root canal disinfection.

Methods

Two reviewers independently conducted a comprehensive literature search using a combination of medical subject heading terms and key words to identify studies relevant to the Population Intervention Control Outcome question. The selection of articles for inclusion was performed in 2 phases based on predetermined eligibility criteria according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Inter-reviewer agreement for each phase was recorded. The effect of PDT on bacterial load reduction during root canal disinfection was evaluated as the primary outcome variable during data extraction.

Results

The literature search provided 57 titles and abstracts. Three articles met the inclusion criteria and were selected for this systematic review. The reasons for study exclusion in each phase were recorded. Because of the heterogeneity in clinical indications and PDT protocols among the included studies, a meta-analysis could not be performed. All included studies showed a positive effect of PDT in the reduction of microbial load in root canal treatment ranging from 91.3%–100%.

Conclusions

Limited clinical information is currently available on the use of PDT in root canal disinfection. If supported by future clinical research, PDT may have efficacy for additional root canal disinfection, especially in the presence of multi–drug-resistant bacteria.     

The Radix Entomolaris and Paramolaris: A Micro–Computed Tomographic Study of 3-rooted Mandibular First Molars

Introduction

The morphology of the supernumerary third root (radix) in mandibular first molars was examined by micro–computed tomography (μCT) scanning.

Methods

Nineteen permanent mandibular first molars with radix were scanned in a μCT device to evaluate their morphology with respect to root length, root curvature direction, location of radix, apical foramen, accessory canals and apical deltas, and distance between canal orifices as well as 2- and 3-dimensional parameters of the canals (number, area, roundness, major/minor diameter, volume, surface area, and structure model index). Quantitative data were analyzed by 1-way analysis of variance and the Tukey test (α = 0.05).

Results

The mean length of the mesial, distal, and radix roots was 20.36 ± 1.73 mm, 20.0 ± 1.83 mm, and 18.09 ± 1.68 mm, respectively. The radix was located distolingually (n = 16), mesiolingually (n = 1), and distobuccally (n = 2). In a proximal view, most radix roots had a severe curvature with buccal orientation and a buccally displaced apical foramen. The spatial configuration of the canal orifices on the pulp chamber floor was mostly in a trapezoidal shape. The radix root canal orifice was usually covered by a dentinal projection. The radix differed significantly from the mesial and distal roots for all evaluated 3-dimensional parameters (P < .05). The radix canal had a more circular shape in the apical third, and the mean size of the minor diameter 1 mm short of the foramen was 0.25 ± 0.10 mm.

Conclusions

The radix root is an important and challenging anatomic variation of mandibular first molars, which usually has a severe curvature with a predominantly distolingual location, and a narrow root canal with difficult access.