BeeFill^TM2in1热牙胶根充系统根充时牙根表面温度变化

目的：研究用红外成像仪监测BeeFill^TM2in1热牙胶根管充填系统根充时牙根表面温度的变化。方法：选取因牙周炎拔除的上下颌单根管中切牙22颗用BeeFill^TM2in1热牙胶根充系统进行根管充填。用红外成像仪跟踪监测从根充开始到完成这一过程中牙根表面温度的变化。结果：牙根表面温度根充后比根充前上颌中切牙平均升高8.2℃,低于引起周围组织损伤的理论阈值温度;下颌中切牙平均升高11.6℃,高于引起周围组织损伤的理论阈值温度。结论：本研究表明BeeFill^TM2in1热牙胶根充系统根充时会引起上、下颌中切牙牙根表面温度升高,但下颌中切牙牙根表面温度升高可能会造成牙周组织损伤,在临床上要谨慎使用。     

Root surface temperature rises during root canal obturation, in vitro, by the continuous wave of condensation technique using System B HeatSource

OBJECTIVES: This in vitro study evaluated increases in root surface temperature during the continuous wave of condensation technique using a System B HeatSource. STUDY DESIGN: Forty-five extracted human teeth (15 maxillary central incisors, 15 mandibular central incisors, and 15 maxillary canines) were used. After root canal cleaning and shaping, the teeth were filled with the continuous wave of condensation technique using a System B HeatSource. Temperature changes on the whole mesial and vestibular outer surfaces of the roots were measured using an infrared thermal imaging camera. RESULTS: The results of this in vitro study showed that the use of the continuous wave of condensation technique to fill the maxillary central incisors and maxillary canines produced temperature rises below the critical level. In the mandibular central incisors the use of a System B HeatSource resulted in elevation of the root surface temperature by more than 10 degrees C. CONCLUSION: The continuous wave of condensation technique using the System B HeatSource produces temperature changes on the outer root surfaces, which, in the case of teeth with relatively thin dentinal walls, can reach relatively high values.     

Distribution of developmental defects of tooth enamel by tooth-type in 11–12-year-old children in South Wales

The distribution of enamel developmental defects in 759 11-12-yr-old children from South Wales is described. Overall, 8% of maxillary teeth were affected compared to 3.6% of mandibular teeth. Most teeth were affected equally on right and left sides of the mouth except for maxillary lateral incisors, which had significantly more defects on the right (P less than 0.05) and maxillary first molars, which had significantly more defects on the left (P less than 0.025). Maxillary central incisors (18.7%) were affected by enamel defects most often followed by maxillary first molars (8.1%) and maxillary lateral incisors (7.2%). The ranking order of the teeth varied when the prevalence of the different types of defects was assessed. White demarcated opacities were seen most often in maxillary central incisors (10.8%), yellow demarcated opacities in maxillary first molars (1.8%), diffuse opacities in maxillary central incisors (6.6%) and hypoplasias in mandibular first premolars (1.5%). Defects of all types occurred most frequently on the buccal surfaces of the teeth. In premolar and molar teeth more defects occurred on the occlusal surface than on the lingual.     

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.     

Distribution of incisor caries in 11- and 12-year old English children.

The prevalence of clinical caries at each approximal site of maxillary and mandibular incisor teeth was determined for 1432 11–12-yr old children. Caries was diagnosed in 12.2 per cent of these children in at least one maxillary incisor approximal site; there was a mean of 2.3 affected teeth in each affected child. The corresponding figures for mandibular incisors were 2.9 per cent and 2.1 affected teeth per affected child. The observed distributions were highly non-random, supporting the findings of Jackson and Burch (1968) and Jackson, Sutcliffe and Burch (1967). However, the patterns of attack in approximal incisor surfaces described in the present study were different from those obtained by Jackson and co-workers. In our investigation, more double attacks at adjacent and homologous surfaces were recorded, so that the single:double ratios were markedly lower than previously reported.     

Morphometric study of length and grooves of maxillary lateral incisor roots

OBJECTIVE: Root grooves are considered a risk factor for periodontal disease. The purpose of this study was to measure the length of the root of maxillary lateral incisors (MLI), as well as the width and depth of the concavities of their proximal surfaces, and also to determine the prevalence of palato-gingival grooves. METHODS: the width and depth of root concavities, as well as root length were evaluated in 73 MLI. All teeth were measured using a digital contour measuring instrument for the root grooves and a caliper for evaluating root length. RESULTS: After statistical analysis (p<0.05) it was possible to confirm: the mean root length on its mesial surface was (15.47+/-1.72 mm), on its distal surface (14.99+/-1.70 mm), on its buccal surface (13.10+/-1.69 mm) and on its lingual surface (12.71+/-1.53 mm); concavities were present in 100% of the samples; concavities were found 2mm, coronally from the CEJ, at the CEJ, and apically up to 8mm; the concavities were wider than deeper; on the mesial surface, the greatest width was (1.05 mm) and the greatest depth was (0.06 mm) both at the CEJ; 5) on the distal surface the greatest width was (0.73 mm) at 6mm apically from the CEJ and the greatest depth was (0.003 mm); the palato-gingival groove was observed in 9.58% of the samples. CONCLUSIONS: The mesial surface of the maxillary lateral incisor is the longest. The root concavities on the proximal surfaces are present in 100%. One must get acquainted to the morphological variations of roots to enhance diagnosis and treatment.     

Differential rates of enamel formation on human tooth surfaces deduced from the striae of retzius

Ten permanent maxillary central and mandibular lateral incisor teeth were sectioned in labio-lingual or mesio-distal planes, and the amount of enamel between two striae of Retzius was measured in the vicinity of the dentine-enamel junction. In the initial third of crown formation of central incisors, both the thickness of enamel and the amount of cervical extension of enamel were always greater on the labial than on the lingual surface; the same applied to the thickness of enamel, but not to the amount of cervical extension of enamel, in the lateral incisors. The thickness of enamel together with its cervical extension was greater on the mesial than on the distal surface in the lateral, but not the central, incisors. In the cervical third of the crown, there was a general tendency for the thickness of enamel and its cervical extension to be greater on the lingual and distal surfaces than on the opposite surfaces. For the maxillary central incisors, it was deduced that the labio-lingual reversion of the rate of development of enamel takes place at approximately the 60 per cent level of the crown formation.     

因重度牙周炎拔除的磨牙根分叉形态测量及根柱凹陷发生率的调查

目的 :了解因重度牙周炎拔除的磨牙根分叉形态及根柱凹陷的发生情况。方法 :对因重度牙周炎拔除的 3 0个上颌第一磨牙 ,15个上颌第二磨牙 ,3 0个下颌第一磨牙及 10个下颌第二磨牙进行测量 ,记录牙根长度(RL) ,根柱长度 (RTL) ,釉牙骨质界处的近远中径 (MDD)和颊舌径 (BLD) ,根柱凹陷的有无 ,釉牙骨质界到根柱凹陷的距离及根分叉开口下 2mm的宽度。结果 :①无论是上颌还是下颌磨牙 ,第一磨牙牙根长度及根柱长度均较第二磨牙短 ,而第一磨牙颊舌径、近远中径及根分叉开口下 2mm处宽度均较第二磨牙大 ,其中仅 4.71%的牙根分叉开口下 2mm处宽度小于 0 .75mm。②上颌磨牙根柱凹陷发生率高于下颌磨牙 ( p <0 .0 5 ) ,且 89.41%的牙至少在一个面上从根柱凹陷到釉牙骨质界的距离为零。结论 :根柱凹陷可能是造成根分叉病变的原因 ,并可能是导致牙周治疗效果欠佳的原因。     

Healing following surgical treatment and root demineralization in monkeys with periodontal disease

Abstract The aim of the present investigation was to study the potential for new attachment to root surfaces which 1) had become devoid of attachment either by mechanical removal or in conjunction with experimental periodontal tissue breakdown and 2) subsequently had been conditioned with citric acid. Three adult monkeys (Macaca cynomolgus) were used. Periodontal pockets were produced during a 2–6-month period around the maxillary central incisors and first and second premolars and around the mandibular central incisors by the placement of orthodontic elastics. Surgical treatment of the pockets was carried out with the use of a flap procedure. During surgery, the roots of the premolars on the right side of the jaws were first scaled and planed and subsequently treated with citric acid. Citric acid conditioning was not performed on the premolars of the left side. In the front tooth regions the surgical treatment included citric acid conditioning of the mandibular central incisors in two animals and of the maxillary central incisors in one animal. Surgical procedures were also carried out around the mandibular second premolars and first molars which had not been exposed to periodontal tissue breakdown. Folio wing flap elevation, the buccal bone plate was mechanically removed within an area corresponding to that of bone loss produced by the experimental periodontitis model in the maxillary premolars. The cementum layer of the surgically denuded portion of the roots was removed by root planing. In all treated teeth, a notch was prepared in the buccal root surfaces at the level of the alveolar bone crest. Six months following treatment the animals were sacrificed and histologic sections prepared. Linear measurements were made along the root surface from the apical border of the prepared notch to the apical termination of the junctional epithelium and to the crest of the alveolar bone. The results demonstrated that cementum formation and new connective tissue attachment did not occur on root surfaces previously exposed to periodontal pockets and subsequently subjected to scaling and root planing or on root surfaces surgically deprived of their supporting bone and previously “non-exposed” cementum layer. Cementum formation and new connective tissue attachment also failed to occur following citric acid conditioning of root dentin surfaces. In all sections representing all three treatment groups, the attachment between the gingiva and the root was established by epithelium.     

老年人群下颌第一磨牙根管结构和近中根根面形态研究

目的:使用CBCT观察老年人下颌第一磨牙根管和牙根牙面形态.方法:纳入98名老年患者的98颗下颌第一磨牙CBCT影像,观察根管结构及近中根根面凹陷情况.结果:老年人下颌第一磨牙的近中根根管结构以Ⅳ型为主,占比78.6％;远中根以Ⅰ、Ⅱ型为主,占比分别为44.9％和12.2％;所有的近中根远中面都存在凹陷,56％近远中面...     

三种矫治器治疗安氏Ⅱ类2分类对切牙牙根吸收的影响

目的 比较不同矫治器治疗安氏Ⅱ类2分类错牙合畸形患者切牙牙根的吸收状况。方法 选择使用不同矫治器的安氏Ⅱ类2分类成年患者30例,其中传统MBT托槽、自锁托槽以及无托槽隐形矫治器的患者各10例,共计240颗切牙。收集患者治疗前后的锥形束CT(CBCT)影像学资料,并导入Dolphin Imaging软件,Mimics软件以及3-Matics软件测量分析治疗前后切牙牙根吸收情况。结果 传统MBT托槽组和自锁托槽组的上下颌中切牙以及侧切牙的牙齿长度(L)与无托槽隐形矫治器组上下颌中切牙及上颌侧切牙的牙齿长度治疗后较治疗前显著减小,差异具有统计学意义。使用无托槽隐形矫治器的患者下颌侧切牙治疗前后的牙齿长度无显著变化。而三组之间的对比,上下颌中切牙牙齿长度变化无显著统计学差异。无托槽隐形矫治器组上下颌侧切牙的牙齿长度减少量相对更低,差异具有统计学意义(P＜0.05)。此外,无托槽隐形矫治器组平均牙齿长度变化为(-0.37±0.11)mm,显著小于传统MBT托槽组(-1.32±0.47)mm及自锁托槽组(-1.05±0.38)mm。在牙根吸收区域的比较上,各组均表现为腭侧吸收多于唇侧吸收,近中吸收多于远中吸收。结论 无托槽隐形矫治器治疗安氏Ⅱ类2分类错牙合畸形可有效降低切牙牙根吸收严重程度。     

运用锥束CT对恒前牙根管变异的分析

目的采用锥束CT扫描所得图像数据,统计和分析前牙根管的变异。方法收集600例患者7200颗前牙图像数据,运用NNT软件,在冠状面、矢状面和横断面进行观察,统计和分析根管的数目、形态变异,根管类型,牙根数及两侧根管变异的对称性。结果 1根管数目：上颌前牙均为单根管,未见到根管变异;下颌前牙中330颗牙出现变异根管,为9.16%;2根管类型：上颌前牙均为Ⅰ型,下颌前牙Ⅰ型90.84%,Ⅱ型0.83%,Ⅲ型6.67%,Ⅳ型1.33%,Ⅴ型0.33%;3根管变异的对称性：上颌前牙不存在变异根管对称;下颌前牙两侧变异根管对称率：中切牙69.2%;侧切牙86.1%;尖牙66.7%;4牙根数：前牙除2例下颌尖牙为双根外,余均为单根。结论上颌前牙未见根管和牙根的变异;下颌前牙根管形态较复杂,根管变异率为9.16%,CBCT可准确发现根管变异。     

Apical Foramen Position in Relation to Proximal Root Surfaces of Human Permanent Teeth Determined by Using a New Cone-beam Computed Tomographic Software

Introduction

The purpose of this study was to determine the position of the apical foramen (AF) in relation to root surfaces of human permanent teeth using cone-beam computed tomographic (CBCT) imaging and novel advanced imaging analysis software (e-Vol DX; CDT Software, Bauru, SP, Brazil).

Investigation of the root canal configurations of mandibular permanent teeth in the Turkish population

AIM: To investigate the root and canal morphology of mandibular permanent teeth collected from an indigenous Turkish population. METHODOLOGY: A total of 1400 extracted mandibular permanent teeth were evaluated. The teeth were divided into seven groups as central incisors, lateral incisors, canines, first premolars, second premolars, first molars and second molars in order to evaluate their root canal configurations. Access cavities were prepared and pulp tissue removed using 5.25% sodium hypochlorite solution. The teeth were stored in 5% nitric acid solution for 5 days, then rinsed under running water for 4 h and placed in increasing concentrations of ethyl alcohol. The teeth were rendered transparent by immersion in xylene solution for 3 days until complete transparency was achieved. Following this procedure, India ink was injected in the root canal systems and their configurations were examined and compared with the classification of Vertucci. The following observations were made: (i) root canal classification of mandibular teeth; (ii) morphology of the mandibular permanent teeth. The classification of Vertucci was taken as a reference during the evaluation; however additional canal morphological types were evaluated as separate groups. RESULTS: The presence of a second canal was detected in 68% of mandibular central incisors and 63% of lateral incisors. Lateral canals were found in 6.5% of mandibular central incisors and in 13% of lateral incisors. Overall, 62% of mandibular first premolar teeth had a single canal whereas 71% of second premolars had a single canal. The mandibular first and second molar teeth exhibited similar root canal configurations except for a group of second molar teeth that had a single root and canal. CONCLUSIONS: The morphological characteristics of teeth in this Turkish population were consistent with those of other studies performed on different populations using similar methodology.     

Dentin permeability of the apical third in different groups of teeth

This ex vivo study evaluated dentin permeability of the root canal in the apical third of different human groups of teeth. Eighty teeth were used, 8 from each dental group: maxillary and mandibular central incisors, lateral incisors and canines, maxillary first premolars (buccal and palatal roots), mandibular first premolars, and maxillary and mandibular second premolars, totalizing 88 roots that were distributed in 11 groups. The root canals were instrumented, irrigated with 1% NaOCl and 15% EDTA. Roots were immersed in 10% copper sulfate for 30 min and then in 1% rubeanic acid alcohol solution for the same period; this chemical reaction reveals dentin permeability by the formation of copper rubeanate, which is a dark-colored compound. Semi-serial 100-μm-thick cross-sections were obtained from the apical third of the roots. Five sections of each apical third were washed, dehydrated, cleared and mounted on glass slides for examination under optical microscopy. The percentage of copper ion infiltration and the amount of tubular dentin were quantified by morphometric analysis. The penetration of copper ions in the apical third ranged from 4.60 to 16.66%. The mandibular central and lateral incisors presented the highest dentin permeability (16.66%), while the maxillary canines and mandibular second and first premolars presented the lowest dentin permeability (4.60%, 4.80% and 5.71%, respectively; p<0.001). The other teeth presented intermediate permeability. In conclusion, dye penetration into dentin tubules at the apical region is strongly dependent on the group of teeth evaluated.     

Mesiodistal root angulation of permanent teeth in children with mixed dentition and normal occlusion

Objective

There is little information regarding the mesiodistal angulation of permanent teeth in mixed dentition. The aim of this study was to evaluate mesiodistal root angulation of permanent incisors, canines and first molars of 100 Brazilian children, using a new horizontal reference plane based on the midpoint of the intercuspation of primary canines and permanent first molars in panoramic radiographs during the mixed-dentition phase.

Material and methods

Children were equally divided between the genders with a mean age of 8.9 years (SD=0.76), normal occlusion and no eruptive disturbances.

Results

The angulation of the permanent maxillary first molars was close to the vertical, whereas the mandibular molars presented approximately 25 degrees of distal root angulation. The maxillary canines were the most distally angulated teeth, whereas the permanent mandibular canines were vertically positioned. The evaluation of the anterior maxillary area showed vertical position of permanent lateral, and central incisors with a slight distal angulation, whereas the permanent mandibular incisors tended to a mesial radicular convergence.

Conclusions

The proposed reference line could be useful in mixed dentition root angulation evaluation; there was a slight asymmetry in the mesiodistal angulation among homologous teeth, and also a small variation between the male and the female groups, but no difference between 8-and 10-year-old children.     

Periapical condition of anterior teeth after surgical correction of mandibular prognathism. A radiographic study.

Extrusion and root resorption of the mandibular anterior teeth have been reported after surgical correction of mandibular prognathism by horizontal osteotomy of the rami. The aim of the present study was to find out whether oblique sliding osteotomy also has such side effects. Intraoral radiographs of the maxillary and mandibular anterior teeth of 61 patients were studied. Enlargement of the periodontal space and signs of root resorption were estimated postoperatively and at a later review 1 1/2-5 years after the operation. Enlargement of periodontal space occurred postoperatively in 16.2% of the maxillary incisors and 52.2% of the mandibular incisors. The enlargements were mostly reversible and at the final review only 1.1 and 8.5% of the maxillary and mandibular incisors, respectively, showed such enlargements. Root resorption was rarely found in radiographs from the postoperative control. At the final review, however, there were signs of root resorption of 1.6 and 20.8% of the maxillary and mandibular incisors, respectively. It appears warranted to conclude that the anterior teeth, especially the mandibular incisors, are exposed to strong forces also after oblique sliding osteotomy of the mandibular rami.     

A controlled study of the morphometric changes in the primary dentition of pre-term, very-low-birthweight children

The aim of the present investigation was to compare the dimensions of the primary incisors from pre-term children and full-term controls. One hundred and eleven pre-term children, consisting of 86 very-low-birthweight (< 1,500 g), 25 low-birthweight (from 1,500 to 2,500 g), and 169 full-term, normal-birthweight (> 2,500 g) children, donated a total of 572 maxillary and mandibular primary central and lateral incisors for study. The teeth were measured by means of a digital micrometer. The results showed that there was a dose-response effect of birthweight on tooth size. The very-low-birthweight teeth showed the smallest dimensions, the normal-birthweight controls the largest, and the low-birthweight teeth intermediate dimensions (p < 0.001). In the maxillary primary central and lateral incisors, and the mandibular primary central incisors, very-low-birthweight teeth were from 6 to 11% smaller in both mesiodistal and faciolingual dimensions compared with normal-birthweight teeth (p < 0.001). The largest differences were observed in the maxillary lateral incisors, where mean decreases of 0.58 +/- 0.45 mm in mesiodistal and 0.50 +/- 0.40 mm in faciolingual dimensions (11% reduction in both measurements) were observed. In addition, in the mandibular and maxillary lateral incisors of very-low-birthweight children, the left-sided teeth were significantly smaller than those on the right side in both mesiodistal and faciolingual dimensions (p < 0.03).     

Relationship between alignment conditions of teeth in anterior segments and incisal wear

This report describes the alignment condition and incisal wear of the anterior teeth in individuals 16–19 years of age. Tooth alignment and incisal wear were assessed on casts in accordance with two index systems NONAT (non-aligned tooth) and IwI (incisal wear index). Tests of the methods showed that the reproducibility of the assessments of tooth alignment and incisal wear were satisfactory. The results of the study of tooth irregularity demonstrated that the prevalence of non-alignment of one or more of the anterior teeth were much the same (∼50%) for the maxillary and mandibular jaws. The highest frequency was found for the maxillary lateral incisors and the mandibular central incisors (∼45%). A relationship between the alignment conditions and incisal wear of the anterior teeth was established. It appeared that non-alignment of one or more teeth in one or both jaws was associated with less severe incisal wear of the anterior teeth. This was most pronounced for non-aligned maxillary central incisors and non-aligned mandibular central incisors.     

A study on the thickness of radicular dentine and cementum in anterior and premolar teeth

AIM: This study aimed to measure the thickness of radicular dentine and cementum in incisors, canines and premolars, and to develop geometric average models. METHODOLOGY: The roots of 220 extracted human teeth were sectioned in three horizontal parallel planes and measured using an optical microscope. For each cut surface buccal, lingual, mesial, and distal thickness of the root wall was measured. Mean values of the thickness at each location of each cut surface were calculated. The observed differences in thickness by tooth type, location, and section were compared by ANOVA and Student's t-test. RESULTS: Maxillary central incisors and maxillary canines had the greatest widths. In all teeth with a single root, the wall thickness were greater on the lingual side than the buccal side. Although differences between mesial and distal thicknesses were not statistically significant. CONCLUSIONS: Wall thickness varied greatly. The lingual surfaces of roots were larger. All roots had thin walls in the apical third.