玻璃纤维桩与金属桩核修复牙体缺损的比较

背景：当冠部牙体组织大面积缺损单纯充填、全冠及嵌体疗效不佳时,桩核系统使残根、残冠的修复成为可能。 目的：分析玻璃纤维桩和铸造金属桩在牙体缺损修复中的临床效果。 方法：将106例患者共160颗患牙随机分为2组,经完善的根管治疗后,分别采用玻璃纤维桩(n=80)和铸造金属桩(n=80)制作桩核,金瓷冠修复,随访9-33个月,评价两组临床修复效果。 结果与结论：玻璃纤维桩治疗成功78颗,桩松动2颗,治疗成功率98%;铸造金属桩治疗成功71颗,冠折1颗,根折4颗,桩脱落4颗,治疗成功率89%,两组治疗成功率比较差异有显著性意义(P < 0.05)。表明玻璃纤维桩在牙体缺损修复中具有操作方便、色泽好且不易造成根折等优点,治疗效果优于金属铸造桩核修复。     

Photomechanical investigations on the stress-strain relationship in dentine macrostructure

In this study photomechanical experiments were carried out to examine the relationship between macroscopic mechanical stress and strain gradients within the root dentine structure. Three-dimensional digital photoelasticity was used to study the stress distribution patterns in tooth models, while digital moire interferometry was used to study the strain gradients within the natural teeth. The stress analysis showed a distinct bending stress distribution, along faciolingual plane in the coronal and cervical regions of the tooth. There was a reduction in bending towards the apical third of the tooth model. The strain analysis displayed strain gradients in the axial (along the long axis of the tooth) and lateral (perpendicular to the long axis of the tooth) directions in dentine. There was a conspicuous reduction in strains from the cervical to the apical third of the root dentine. The root dentine displayed uniform distribution of normal strains. Although there was a steep increase in stresses from the inner core region to the outer surface of an isotropic tooth model, there were more uniform strain gradients in the natural dentine structure. It is apparent from these observations that complex organization of material properties facilitated distinct strain gradients in dentine structure during mechanical functions.     

两种形态玻璃纤维根管桩修复残冠的2年随访

背景：临床上多采用平行或锥形玻璃纤维根管桩修复根管治疗后的残根残冠,但两种形态根管桩的临床效果还有待证实。 目的：评价残冠修复时使用平行及锥形玻璃纤维根管桩的临床疗效。 方法：选择残冠患者121例,共156颗患牙,经完善的根管治疗后采用掷硬币法随机分为两组,分别采用平行玻璃纤维根管桩与锥形玻璃纤维根管桩重建桩核,然后以全瓷或金属烤瓷冠修复。术后每半年复查1次,分别对修复体的稳固性、边缘密合性、牙周组织情况、咬合功能等方面进行临床评价,观察期为2年。 结果与结论：121例患者均完成2年的随访观察。平行玻璃纤维根管桩组根管桩自牙颈部折断1例,治疗成功率为98.7%;锥形玻璃纤维根管桩组根管桩折断1例,根管桩连同全冠完整脱落1例,经重新粘接后行使功能良好,治疗成功率为97.5%;两组间治疗成功率差异无显著性意义(P > 0.05)。说明两种形态的玻璃纤维根管桩均可取得令人满意的临床效果,但远期疗效尚有待进一步观察。     

Difference in the periapical status of endodontically treated teeth between the samples of Croatian and Austrian adult patients

Aim. To compare the periapical status of endodontically treated teeth between Austrian and Croatian adult patients and determine its relation to age, sex, position of teeth, and length of root canal filling. Methods. The study was conducted from 2007 to 2009 at two university dental clinics and included 163 Croatian (412 teeth) and 101 Austrian (430 teeth) patients. We assessed the periapical status of endodontically treated teeth by using the periapical index system and determined its relation to age, sex, position of teeth, and length of root canal filling. Results. Austrian patients had a greater number of diseased endodontically treated teeth than Croatian patients (P=0.001). In the age group 31-40 years, Austrian patients had apical periodontitis significantly more often (22.1% vs 12.2%, P<0.001) than Croatian patients. In relation to sex and position of teeth, no significant difference was found between the two groups. In Croatian patients, apical periodontitis was significantly more often present in molar than premolar (46.2% vs 29.7%, P=0.022) and front teeth (46.2% vs 24.1%, P<0.001). In Austrian patients, apical periodontitis was significantly more often present in molar and premolar than front teeth (molar-front teeth: 38.2% vs 25.5%, P=0.011; premolar-front teeth: 36.3% vs 25.5%, P=0.029). Croatian and Austrian patients with AP significantly differed in the number of adequately filled and underfilled teeth (both P<0.001). Conclusion. Apical periodontitis was significantly more present in endodontically treated teeth in Austrian patients. The difference in the periapical status between Croatian and Austrian patients was most related to age and length of root canal filling.     

铸造桩核烤瓷冠修复前牙残冠残根126颗疗效观察

随着根管治疗学的进一步发展,越来越多的残冠及残根能够长期保留,这就为铸造桩核烤瓷冠修复法提供了可能,因而对某些残冠及残根的进一步修复显得尤为重要。本文选取铸造桩核烤瓷冠修复前牙残冠残根20例患者126颗患牙,将其疗效报告如下。     

Serological investigations on Indian kala-azar.

Detailed serological investigations were carried out in forty-nine active kala-azar (KA) cases in North Bihar, India. Various classes of immunoglobulin (IgG, IgA, and IgM) and third component of complement (C3) levels were determined in these sera and results were compared with those obtained in normal controls. Antibody titres were determined by the indirect haemagglutination (IHA) method using soluble Leishmania antigen. Immunoglobulin G and M class-specific antibody titres were also determined separately by the enzyme-linked immunosorbent assay (ELISA) method. Polyclonal hypergammaglobulinaemia with marked increase in serum IgG (and to a lesser extent in IgM) level was a rather common feature in the majority of these sera. Much of this immunoglobulin increase, however, appeared to be non-specific in nature and no absolute correlation could be noted between serum IgG or IgM levels and corresponding IgG or IgM antibody titres. Significant decrease in serum C3 level was observed in KA and this decrease was found to be independent of immunoglobulin levels or specific antibody titres. A fairly good correlation between aldehyde test and serum IgG level was evident from this study. Aldehyde-positive KA sera usually gave higher antibody titres than aldehyde-negative ones. Anti-leishmanial antibodies belonged mostly to IgG class although some IgM antibodies were also demonstrable. The latter class of antibodies probably appeared early in KA infection although their serological specificity was poorer to IgG antibodies. Out of forty-nine KA sera examined in this study thirty-six (73.5%) gave positive IHA titres while forty-six (93.9%) were positive by IgG-ELISA which appeared to be a highly specific and sensitive serodiagnostic method particularly for the early detection of KA cases.     

Experimental investigations on immunology of the parathyroid gland

Repeated inoculation of homologous parathyroid tissue in dogs induced isoimmune hypoparathyroidism, with all the characteristic biochemical and histopathological features and the presence of complement fixing antibodies in the serum.

Disturbances of calcium and phosphorus metabolism were similar to, but less severe than, those observed in dogs with hypoparathyroidism induced by complete thyro-parathyroidectomy.

Injection of rabbits with crude extracts of dog, rat, hog and human parathyroid or with bovine parathormone (PTH), each incorporated in Freund's adjuvant, resulted in the development of complement fixing and precipitating antibodies: these reacted with the corresponding tissue preparations, but did not show cross-reactivity. Antibodies were not detected in the serum of normal dogs or in control dogs inoculated with Freund's adjuvant alone.

Study of the parathyroid glands by electron microscopy provided information on the mechanism of PTH secretion and synthesis in normal dogs and in those with hypoparathyroidism.

     

Advanced digital photoelastic investigations on the tooth-bone interface

The purpose of this study was to investigate the behavior of the tooth-bone interface on the nature of stress distribution in the tooth and its supporting alveolar bone for various occlusal loads using an advanced digital photoelastic technique. A digital image processing system coupled with a circular polariscope was used for the stress analysis. The phase shift technique and a phase unwrapping algorithm was utilized for fringe processing. This aids in obtaining qualitative and quantitative information on the nature of stress distribution within the dento-osseous structures. The experiments revealed bending stresses within dento-osseous structures. However, the compressive stress magnitude was larger than the tensile stress. Zero stress regions were also identified within the dento-osseous structures. The results suggest that the geometry of the dento-osseous structures and the structural gradients at the tooth-bone interface play a significant role in the distribution of stresses without stress concentrations. Further, the application of an advanced image-processing system with the circular polariscope showed notable advantages and could be applied in other biomechanical investigations.