Root length in transplanted premolars

The objectives of the present prospective longitudinal study were to establish the survival and success rates for premolars with partly developed roots transplanted according to a set protocol, and to analyze the effect of varying pre‐surgery root development on final root length. Standardized periapical radiographs of 132 consecutively transplanted premolars were obtained at predetermined intervals over a 4‐year follow‐up period. Survival and success rates were calculated on the basis of presence of teeth and recording of defined radiological variables, respectively. Final root length was compared to normative metric data for root morphology. From the total sample, 54 patients with 68 transplanted premolars suitable for analysis of root growth relative to initial root length were identified, and divided into subsamples according to root length pre‐transplantation. Survival rates were 100% after 1, 2, and 3 years, and 98.6% 4 years post‐transplantation. The success rates were 92.9%, 92.8%, 89%, and 90.5% in subsamples collected 1, 2, 3, and 4 years after transplantation, respectively. The transplants obtained on average 78% of normative root length, and by dichotomizing the transplanted teeth in subsamples with ‘short’ and ‘long’ roots pre‐surgery, similar final root lengths were observed even if ‘short’ roots had the greatest increase. Very early transplantation (roots <7 mm), however, tended to result in short final root length. It is concluded that the success and survival rates were comparable to results obtained in similar studies. Initial root length was a significant predictor of root length increase. Transplanting teeth with short roots is to risk short final root length.     

Morphometric evaluation of changes in the alveolar bone and roots of the maxillary anterior teeth before and after en masse retraction using cone-beam computed tomography

Objective:To evaluate the morphometric changes in the alveolar bone and roots of the maxillary anterior teeth (MXAT) after en masse retraction with maximum anchorage (EMR-MA).Materials and Methods:The samples consisted of 37 female adult patients who had Class I dentoalveolar protrusion (CI-DAP) and were treated by extraction of the first premolars and EMR-MA. Using three-dimensional cone-beam computed tomography taken before treatment and after space closure, the maxillary central incisors (MXCI, N  =  66), lateral incisors (MXLI, N  =  69), and canines (MXC, N  =  69) were superimposed using individual reference planes. After alveolar bone area (ABA), vertical bone level (VBL), root length (RL), root area (RA), and prevalence of dehiscence (PD) were measured at the cervical, middle, and apical levels, statistical analyses were performed.Results:On the palatal side, ABA significantly decreased in all levels of MXAT (P < .001; middle of MXC, P < .01). MXCI and MXLI exhibited a greater decrease in the ratio of change in palatal ABA than did MXC (cervical, P < .01; middle and apical, P < .05; total, P < .001). Palatal/labial ABA ratios decreased in MXCI (cervical, middle, total, P < .001; apical, P < .05) and MXLI (cervical, P < .001; apical, P < .05). They showed greater amounts and ratios of change in VBL on the palatal side compared to the labial side (all P < .001). The palatal side showed more PD in the cervical area than did the labial side (MXCI and MXLI, P < .001; MXC, P < .01). Significant root resorption occurred in MXAT (RL and RA, all P < .001).Conclusions:During EMR-MA in cases with CI-DAP, ABA and VBL on the palatal side and RL and RA of MXCI and MXLI were significantly decreased.     

Apical root resorption due to orthodontic treatment detected by cone beam computed tomography

Objective:To determine the frequency of apical root resorption (ARR) due to orthodontic treatment using cone beam computed tomography (CBCT) in a sample of 1256 roots from 30 patients.Materials and Methods:All patients had Class I malocclusion with crowding. Of the 30 patients evaluated, 11 were boys and 19 were girls; their mean age was 13 years (11 to 16 years). Orthodontic treatment followed the nonextraction treatment. CBCT images were obtained before and after orthodontic treatment, and ARR was determined using Axial Guided Navigation of CBCT images.Results:All patients had ARR. No statistically significant association was found between resorption frequency, gender, and age. ARR was detected using CBCT in 46% of all roots that underwent orthodontic treatment.Conclusions:CBCT was effective for detecting in vivo even minimal degrees of ARR due to orthodontic treatment and allowed three-dimensional evaluation of dental roots and visualization of palatine roots of maxillary molars. The highest frequencies and the most significant ARR occurred in incisors and distal roots of first maxillary and mandibular molars.     

Anatomy of sodium hypochlorite accidents involving facial ecchymosis—A review

Objectives

Root canal treatment forms an essential part of general dental practice. Sodium hypochlorite (NaOCl) is the most commonly used irrigant in endodontics due to its ability to dissolve organic soft tissues in the root canal system and its action as a potent antimicrobial agent. Although NaOCl accidents created by extrusion of the irrigant through root apices are relatively rare and are seldom life-threatening, they do create substantial morbidity when they occur.

Methods

To date, NaOCl accidents have only been published as isolated case reports. Although previous studies have attempted to summarise the symptoms involved in these case reports, there was no endeavour to analyse the distribution of soft tissue distribution in those reports. In this review, the anatomy of a classical NaOCl accident that involves facial swelling and ecchymosis is discussed.

Results

By summarising the facial manifestations presented in previous case reports, a novel hypothesis that involves intravenous infusion of extruded NaOCl into the facial vein via non-collapsible venous sinusoids within the cancellous bone is presented.

Conclusions

Understanding the mechanism involved in precipitating a classic NaOCl accident will enable the profession to make the best decision regarding the choice of irrigant delivery techniques in root canal débridement, and for manufacturers to design and improve their irrigation systems to achieve maximum safety and efficient cleanliness of the root canal system.     

Repair processes of experimental root fractures in rat molars examined by histopathological techniques and 3D micro-CT imaging

AimsThe purpose of this study was to investigate the repair processes of experimental intra-alveolar root fractures of immature rat molars with histopathological techniques and 3-dimensional micro-computed X-ray tomography (3D micro-CT) imaging.MethodsTwelve left upper first molars of 4-week-old rats were dislocated toward the palate with modified Hoe's pliers at a load of 900 g for 20 s, and repositioned. After 1 or 2 weeks, the maxillae were dissected and scanned with micro CT for 3D micro-CT imaging. After standard histological preparation, buccolingual serial sections of the maxillae were stained with hematoxylin and eosin or Masson–Goldner stain and observed by light microscopy. Subsequently, we examined the identified root fracture lesions by 3D micro-CT imaging and histopathological sections.ResultsWe identified 6 intra-alveolar vertical incomplete fracture lines in the mesial roots. Histopathological findings showed that newly differentiated odontoblast-like cells had formed immature reparative dentin on the pulpal side of the fracture line at 1 postoperative week, and deposited reparative dentin with a tubular structure at 2 weeks. While surface resorption and granulation-tissue formation occurred on the periodontal side of the fracture line, the narrow fracture line remained unchanged, and the surface resorption lacunae were partly covered with cementum at postoperative 2 weeks.ConclusionsRoot-fracture investigation requires a combination of histopathological observation and 3D-CT imaging. Intra-alveolar fractured root repair accompanied by tubular reparative dentin formation at the pulpal side, and the deposition of cementum at the periodontal side, may occur when the fracture line is too narrow for the formation of granulation tissue.     

不同根管牙本质表面处理对树脂水门汀粘接强度的影响

目的 比较不同根管牙本质表面处理对树脂水门汀粘接强度的影响.方法 24颗单根管离体前磨牙在釉牙骨质界处截冠后行根管充填,实验随机分为四组:A组为对照组(无表面处理);B组为冲洗处理组(17％EDTA 10ml和5％NaClO10ml联合冲洗根管各30s);C组为酸蚀处理组(35％磷酸酸蚀根管30s);D组为冲洗+酸蚀处理组(先17％EDTA10ml和5％NaClO10ml联合冲洗根管各30s;后用35％磷酸酸蚀根管30s).用PULPDENT树脂水门汀进行粘接.自凝塑料包埋牙根,切割为1 mm厚的试件,并将其按照根管的深度分为根尖、根中、根冠3组,测试其粘接强度.记录数值并进行统计分析.结果 与A组相比,B组、C组和D组冲洗桩道后,三个区段的根管牙本质与树脂水门汀的粘接强度均明显增加,差异有统计学意义(P＜0.01),其中以D组的粘接强度最高,D组根尖段与其他两段间的粘接强度差异有统计学意义(P＜0.01);三组实验组的根中段和根冠段之间差异没有统计学意义(P＞0.05).无论是对照组还是实验组,根尖段牙本质与树脂水门汀的粘接强度均为最低,根冠段最高,且差异具有统计学意义(P＜0.01).结论 (1)采用冲洗处理、酸蚀处理和冲洗+酸蚀处理根管壁均能增强根管牙本质与树脂水门汀的剪切粘接强度;(2)根管部位对根管牙本质与树脂水门汀的剪切粘接强度有影响.     

牙周内窥镜下刮治与传统刮治对龈下牙石清除效果的比较

目的比较内窥镜下龈下刮治与传统龈下刮治清除龈下牙石的效果。方法收集16例患者26颗无保留价值的重度慢性牙周炎患牙,随机分为两组,每组8例13颗患牙,分别行牙周内窥镜下龈下刮治(A组)及传统龈下刮治(B组),每颗患牙均刮治10min后拔除,亚甲基蓝染色后,蓝色显示残留牙石,对每颗牙颊、舌、近中及远中面拍照并用Image Pro Plus图像分析软件检测、计算各牙面的牙石残留率。比较两组患牙治疗后的牙石残留率以及吸烟、牙周探诊出血位点数和牙周探诊深度对牙石清除效果的影响。结果 A组患牙平均牙石残留率为(8.34±1.70)%,B组患牙平均牙石残留率为(13.02±3.36)%,差异有统计学意义(P<0.05)。吸烟、探诊出血位点数、牙周探诊深度对治疗后的牙石残留率均有影响(P<0.05)。结论在牙周内窥镜下行龈下刮治,清除牙石的效果明显优于传统龈下刮治。吸烟、探诊出血、探诊深度对牙石残留率均有影响。     

Analisi della morfologia radicolare e canalare di molari superiori ed inferiori in una popolazione Caucasica: studio in vivo alla CBCT

AimTo investigate the root and canal morphology of maxillary and mandibular permanent molar teeth in a Caucasian population by using Cone Beam Computed Tomography (CBCT).MethodsA total of 596 permanent molars were included. The number of roots, the number of canals per root and the root canal configurations according to the method of Vertucci were recorded.ResultsAlmost all of maxillary first molars (95.7%) had three separate roots; however, 40.3% of mesiobuccal roots had two canals (MB2). Of 157 maxillary second molars, 88.5% had three roots. Among the mesiobuccal roots, 15.1% had two canals. The majority of mandibular molars (100% of first molars, 89.4% of second molars) had two separate roots. Most distal roots had a simple type I configuration, whereas mesial roots had more complex canal systems, with more than one canal.ConclusionsCBCT is an efficient method of studying root canal systems.     

超声器械与手用器械龈下刮治疗效比较的meta分析

目的：通过Meta分析评价超声器械与手用器械龈下刮治比较治疗成人慢性牙周炎的临床疗效。方法：计算机检索PubMed、CochraneLibrary、EMbase、CNKI、CBM、WanFangData等6个电子数据库,查找所有有关超声与手工龈下刮治比较治疗慢性牙周炎的随机对照试验（RCTs）。并追索所有纳入文献的参考文献,文献检索时限均从建库至2012年11月。由2名评价员按照纳入和排除标准独立进行文献筛选、资料提取和质量评价后,采用RevMan5．0软件进行Meta分析。结果：最终7个RCT、224例受试者纳入本系统评价。Meta分析结果显示,超声与手工龈下刮治术后3个月复查时探诊深度、附着水平的改变无统计学差异;术后6个月复查时探诊深度、附着水平的改变无统计学差异。结论：现有研究证据表明,在牙周基础治疗过程中,采用超声与手工两种方法进行龈下刮治疗效相似。