C-shaped canal system in mandibular second molars Part III: The morphology of the pulp chamber floor

The purpose of this study was to investigate the morphology of pulp chamber floors in mandibular second molars with a C-shaped canal system. Forty-four extracted mandibular second molars with C-shaped roots were collected from a native Chinese population. After the teeth were scanned by the micro-computed tomography (microCT), the pulp chamber floors were reconstructed three-dimensionally using three-dimensional software. The reconstructed images were classified into four types based on the shape of the pulp chamber floor and the location of the dentin fusion between the peninsular-like floor and the pulp chamber wall. Of the 44 reconstructed pulpal floors, 38 (86.37%) were C-shaped (peninsula-like floor) in which 8 (18.18%) had a continuous C-shaped orifice (type I); 16 (36.37%) had a dentin fusion between the peninsula-like floor and buccal pulp chamber wall, forming one or two mesial orifice(s) and a distal orifice (type II); and 14 (31.82%) had a dentin fusion between the peninsula-like floor and the mesial pulp chamber wall, forming a large mesiobuccal-distal (MB-D) orifice and a small mesiolingual orifice (type III). Six (13.63%) teeth did not have a C-shaped floor configuration (type IV). The number and configuration of the canals at different levels below the orifices were analyzed. The results suggested that most teeth in this study with C-shaped roots also have a C-shaped pulpal floor and that a new classification of pulpal floor anatomy would be helpful in locating the C-shaped canals.     

乳磨牙髓室底穿孔治疗方法的探讨

目的:探讨乳磨牙髓底穿孔后,保留患牙的治疗方法。方法:清除穿孔处炎性感染物质后,常规根管治疗,用复方抗生素糊剂覆盖髓底穿孔处,双层基底封闭髓室底。结果:该方法有效地控制了炎症,保存了患牙。治疗成功率92.96%。结论:去除局部炎性组织后,运用复方抗生素糊剂覆盖髓底穿孔,能够有效地保留患牙,达到乳恒牙顺利替换的目的。     

A study of the dentinal permeability of the pulp chamber floor of human lower molars with separate roots

The permeability of the dentin of the pulp chamber floor of lower molars with separate roots was studied, after instrumentation of the root canals by manual or ultrasonic techniques. The dentinal permeability was evaluated by the degree of penetration of copper ions in the tissue and quantified by methods used in morphometry. None of the combinations of irrigating solution/instrumentation technique caused an increase in the permeability of dentinal tissue in the pulp chamber region, probably because the dentin is reparative dentin, which is more amorphous and less tubular than primary dentin.     

The floor of the pulp chamber following pulpotomy.

The purpose of this study was to investigate the incidence of pulpal floor damage caused by operator error in a standard pulpotomy exercise, and to determine if this damage produced significant changes in dentin morphology and thickness at the base of the pulp chamber. One hundred and fourteen primary molar teeth were utilized in this study, 61 having pulpotomies and the remainder untreated. The dentin thickness in the furcation was measured on all the teeth and the pulpal floor morphology was examined using both light and scanning electron microscopy. The difference in thickness of dentin in the furcation of pulpotomized and non-pulpotomized teeth was not statistically significant. Less than fourteen per cent of pulpotomized teeth showed damage to the pulpal floor and this damage was only minimal in all cases. This study therefore suggests that damage to the pulpal floor during preparation is unlikely to be a factor contributing to failure of pulpotomies.     

Effect of bleaching agents on bonding to pulp chamber dentine

AIM: To determine the effect of intracoronal bleaching agents on adhesion of bonding agents to pulp chamber dentine. METHODOLOGY: Forty extracted human maxillary anterior teeth were randomly divided into four groups of 10 teeth each. Bleaching agents were sealed in pulp chambers for 7 days, as in clinical use. Group 1 (control): distilled water, group 2: 35% hydrogen peroxide, group 3: sodium perborate mixed with water, and group 4: sodium perborate mixed with 35% hydrogen peroxide. Teeth were stored in saline at 37 degrees C for 7 days. After the bleaching agent was removed, teeth were leached in water for a further 7 days prior to bonding. The crown was cut vertically from mesial to distal and the labial pulp chamber dentine was prepared for bonding with Clearfil SE-Bond and filled with resin composite (Clearfil AP-X). The bonded specimens were kept moist at 37 degrees C for 24 h. Microtensile bond strengths were determined using a universal testing machine. Additional teeth were prepared using the same bleaching procedures to investigate the scanning electron microscopic appearance of the dentine surface. RESULTS: Mean values (+/-SD) of microtensile bond strength for the experimental groups were: group 1: 5.29 +/- 2.21 MPa, group 2: 5.99 +/- 1.51 MPa, group 3: 9.17 +/- 1.65 MPa and group 4: 3.99 +/- 1.31 MPa. Dentine treated with sodium perborate in water (group 3) had significantly higher mean bond strength when compared with the other three groups (P < 0.05, Tukey's test). Mean bond strength was lowest when dentine was treated with sodium perborate plus hydrogen peroxide (group 4). CONCLUSIONS: In terms of subsequent bond strength during restoration, sodium perborate mixed with distilled water appears to be the best intracoronal bleaching agent.     

CBCT髓室底3D重建在牙髓根尖周疾病中的应用

目的 分析评估采用CBCT(锥形束计算机断层扫描,Cone Beam Computed Tomography)进行髓室底3D重建在牙髓根尖周疾病中的应用价值.方法 对我院口腔科于2015年11月至2016年3月所做的15例磨牙CBCT使用OnDemand 3D Dental软件进行3D髓室底重建并分析图像,与传统CBCT断层图像进行对比,观察其在临床中的作用.结果 CBCT髓室底3D重建技术能为临床医生提供直观信息,显著提高诊治效率.结论 CBCT髓室底3D重建可明确髓室底情况,确定根管口位置,为根管治疗提供优于传统CBCT断层图像的直观信息.     

生物活性玻璃微粒修复髓室底穿孔的临床观察

目的观察生物活性玻璃微粒(Bioglass)修复髓室底穿孔的临床疗效.方法选择髓室底穿孔病例75例,患牙86个,随机分为两组,试验组采用生物活性玻璃微粒,对照组采用光固化玻璃离子修复.1年后观察临床效果.结果试验组成功率81.3%,进步13.9%,对照组成功率46.5%,进步23.3%,两组间有显著性差异(P<0.05).其疗效与穿孔直径密切相关,与穿孔原因关系不明显.结论生物活性玻璃微粒是一种良好的髓室底穿孔的修复材料.     

髓室底开窗术治疗根分叉区病变临床研究

目的评价髓室底开窗术治疗Ⅱ、Ⅲ度根分叉区病变的方法和疗效。方法对28例31颗根分叉区病变牙，经髓室底开窗、清除病灶，填塞羟基磷灰石等方法的处理，进行临床观察分析。结果经近三年时间临床观察成功率占90.3％，失败3例，其中2例均为选择病例不当。结论髓室底开窗术治疗Ⅱ、Ⅲ度根分叉区病变疗效是肯定的。     

Age-related changes in the pulp chamber of maxillary and mandibular molars on cone-beam computed tomography images

Objectives

Secondary dentine is laid on pulp chamber walls with increasing age, and decreases pulp chamber size. This study aimed to investigate age estimation on cone-beam computed tomography (CBCT) images for forensic science, and the relationship between age and pulp chamber area of maxillary and mandibular molars.

Methods

We reviewed the CBCT images of 316 first molars in 87 patients with dental lesions. The 87 patients were classified into three groups: younger, 11–28 years; middle-aged, 34–59 years; and older, 60–74 years. The relationship between age and pulp chamber area of maxillary and mandibular molars was evaluated.

Results

The mean pulp chamber area of maxillary molars was 8.4 ± 2.0, 4.4 ± 1.7, and 2.9 ± 0.9 mm² in the younger, middle-aged, and older groups, respectively, (p = 0.028). The mean pulp chamber area of mandibular molars was 10.5 ± 2.3, 6.7 ± 2.2, and 3.7 ± 1.5 mm² in the younger, middle-aged, and older groups, respectively, (p = 0.000). The mean pulp chamber area of mandibular molars was larger than that of maxillary molars in the younger (p = 0.000), middle-aged (p = 0.000), and older (p = 0.094) groups. The mean pulp chamber area of maxillary and mandibular molars was significantly correlated with age [Y = ?0.142X + 11.582 (R ² = 0.586, p = 0.000) and Y = ?0.163X + 14.249 (R ² = 0.609, p = 0.000), respectively].

Conclusions

These findings should be useful for diagnosis and treatment planning in dental practice and age estimation in forensic science.

     

离体上颌磨牙髓室底形态的比较研究

目的通过对上海地区成年男女上颌第一磨牙和第二磨牙髓室底形态的观察及根管口距离的测量．用相对直观的方法确定根管口的基本位置。并对所测上颌第一磨牙和第二磨牙的数据进行统计学分析和比较,为临床医生在根管治疗时提供更为丰富的解剖学资料。旨在提高临床根管治疗的成功率。方法取上海地区成年人离体牙：上颌第一磨牙38颗。上颌第二磨牙39颗,以釉牙骨质界为基准横截牙颈部且完整暴露根管口在放大镜下观察其髓室底的形态并测量根管口间的距离。结果“Y”形髓室底沟：上颌第一磨牙占50．00％,上颌第二磨牙占58．97％;“7”型分别为：36．84％和25．64％;根管口的间距：腭根管口至近中颊根管口和远中颊根管口的距离上颌第一磨牙为4．92和3．96,上颌第二磨牙为3．53和2．92;近远中根管口的距离分别为2．01和1．68。结论临床可沿髓室底沟根据腭侧根管口和颊侧根管口的间距寻找上颌磨牙的根管．进行有效的根管治疗。     

Brushite in the pulp of primary molars

This study was undertaken to investigate the mineral phase of spherulitic calcifications discovered in the pulpous mesenchyme of human primary molars by microradiography. Analytical scanning electron microscopy and x-ray diffraction disclosed that well-crystallized brushite is the major compound of the spherulites. The mechanism leading to the crystallization of brushite is far from well understood. Histologically, on decalcified sections, inflammatory cells and capillaries can be seen trapped in the spherulites. In the light of these findings, it could be suggested that metabolic conditions may promote the crystallization of brushite in the pulp of primary molars.     

应用髓室固位的金属嵌体冠修复磨牙重度牙冠缺损

目的:评价利用髓室同位制作嵌体冠修复磨牙残冠的效果.方法:对61颗磨牙残冠经完善根管治疗后,制作髓室固位的铸造金属嵌体冠,修复完成后,定期进行临床检查,评价修复效果.结果:经过1～5a的随访观察,61颗患牙经过修复治疗后获得满意效果,个别病例出现修复体颈缘密合不良、牙龈炎.或继发龋、食物嵌塞.结论:利用髓室固位的铸造金属嵌体冠治疗磨牙残冠,是一种简单易行、经济实惠、效果良好的修复方法,严格选择适应证以及准确的牙体预备和精确的加工制作,是修复成功的关键.