纤维桩不同长度对纤维树脂桩核修复体抗折能力的影响

目的：评价侧向加载条件下纤维桩在根管内的长度对纤维桩复合树脂核修复体抗折性能的影响。方法：选择下颌单根管前磨牙36颗,随机分为6mm、9mm和12mm的3个组,将离体牙行纤维桩修复后使用速率为0．2mm／min的135°角侧向加载。结果：桩长度为6mm组的荷载力值明显的低于其余2组的荷载力值,其差异有统计学意义（P〈0．05）。结论：对于纤维桩复合树脂核修复体,当桩在根管内的长度小于临床牙冠时,修复体的抗折能力较低,因此,临床上尽可能的达到一定的长度,以消除临床失败几率。     

模拟正畸牵引术联合肩领设计对残根抗折力的影响

目的 探讨不同高度的牙本质肩领设计对预成碳纤维桩核修复后牙体抗折力的影响.方法 24颗完整、离体、单根管下颌第一前磨牙于颊侧釉牙骨质界上1.0 mm处截冠,经根管治疗后制备残根模型.通过模拟正畸牵引术(牙合)向牵引残根并在残根颈部预备一定高度的牙本质肩领;按预备的牙本质肩领高度不同(0.0、1.0、2.0 mm)依次分为A、B、C三组,预成碳纤维桩核联合铸造全冠修复残根.试件自全冠颈缘完成线下2.0 mm包埋于自凝塑料内,电子万能试验机以与牙长轴成150°、横梁位移速度1.0 mm/min于颊尖顶加载,测定折裂载荷并进行统计分析.结果 三组试件的折裂载荷(kN)均值依次为(1.13±0.15)、( 1.63±0.14)、(1.92±0.19).预备牙本质肩领可显著提高牙体的折裂载荷(F=48.437,P＜0.001);并且随着预备的牙本质肩领高度增加,牙体的折裂载荷显著增大(P＜0.05).结论 在残根颈部设计牙本质肩领,可明显提高牙体的折裂载荷.     

Repairing a relationship imperiled by infidelity: combining individual work,Relationship Enhancement® couple therapy and guided visualization to break through an emotional impasse

This article presents an extended case analysis involving the impact of infidelity on an intimate relationship where the emotional connection between the two partners runs very deep but where the involved partner's multiple infidelities and the hurt partner's wounded and defended heart keep them stuck, the couple neither being able to end the relationship nor heal from the emotional trauma to the relationship. The analysis relates the intensive individual work with the involved partner on his personal struggles with ego-driven serial infidelity, the joint work with both partners utilizing the Relationship Enhancement® therapy dialogue process and how the spontaneous introduction of an image and guided visualization helped break the emotional impasse in a manner that permitted the couple to move to a place of genuine healing and reconciliation.     

The psychological sequelae of thermal injury on children and adolescents: Part 1

The psychological effects of thermal injury and children and their mothers were investigated in a three-part study; Part 1 is concerned with group comparisons regarding the psychological effects of thermal injury on children; Part 2 with aspects of the thermally injured group and Part 3 with psychological effects on their mothers. A total of 44 thermally injured (aged 11–16 years) injured 3–14 years previously, were matched according to age, sex, burn percentage and site of injury. In-depth interviewing and questionnaire responses on measures of psychological disturbance indicated that thermally injured children were differentiated in terms of psychopathology from matched Fracture Controls and Normal Controls. Such differences embraced many aspects of social and recreational functioning, and group differences emphasised depression, anxiety (particularly situational anxiety) and anti-social disorder as being particularly prominent in the thermally injured group. Therapeutic approaches are briefly discussed.     

Laser Therapy as an Effective Method for Implant Surface Decontamination: A Histomorphometric Study in Rats

Background: To the best of the authors’ knowledge, a standard protocol for treating peri‐implantitis is not yet established. Methods: A total of 150 titanium disks with smooth or rough surfaces contaminated with microbial biofilm were implanted subcutaneously in rats after undergoing one of three treatments: 1) low‐intensity laser (LIL); 2) antimicrobial photodynamic therapy (aPDT); or 3) toluidine blue O (TBO). Sterile and contaminated disks served as negative (NC) and positive (C) control groups, respectively. After days 7, 28, and 84, tissue inflammation was evaluated microscopically by measuring the density of collagen fibers (degree of fibrosis) and concentration of polymorphonuclear neutrophils. Results: Surface texture did not affect the degree of inflammation, but the area of reactive tissue was significantly greater for rough implants (2.6 ± 3.7 × 10⁶ µm²) than for smooth ones (1.9 ± 2.6 × 10⁶ µm²; P = 0.0377). Group C presented the lowest and group NC presented the highest degree of fibrosis with significance only after day 7; these groups had the highest and lowest scores, respectively, for degree of inflammation. Group C showed the largest area of reactive tissue (9.11 ± 2.10 × 10⁶ µm²), but it was not significantly larger than group LIL (P = 0.3031) and group TBO (P = 0.1333). Group aPDT showed the smallest area (4.34 ± 1.49 × 10⁶ µm²) of reactive tissue among the treatment groups. After day 28, groups LIL, aPDT, TBO, and C resembled group NC in all the studied parameters. Conclusion: Group aPDT showed more favorable results in parameter area of reactive tissue than the other methods after day 7, but over longer time periods all methods produced outcomes equivalent to sterile implants.     

Fatigue of dental ceramics

Objectives

Clinical data on survival rates reveal that all-ceramic dental prostheses are susceptible to fracture from repetitive occlusal loading. The objective of this review is to examine the underlying mechanisms of fatigue in current and future dental ceramics.

Data/sources

The nature of various fatigue modes is elucidated using fracture test data on ceramic layer specimens from the dental and biomechanics literature.

Conclusions

Failure modes can change over a lifetime, depending on restoration geometry, loading conditions and material properties. Modes that operate in single-cycle loading may be dominated by alternative modes in multi-cycle loading. While post-mortem examination of failed prostheses can determine the sources of certain fractures, the evolution of these fractures en route to failure remains poorly understood. Whereas it is commonly held that loss of load-bearing capacity of dental ceramics in repetitive loading is attributable to chemically assisted ‘slow crack growth’ in the presence of water, we demonstrate the existence of more deleterious fatigue mechanisms, mechanical rather than chemical in nature. Neglecting to account for mechanical fatigue can lead to gross overestimates in predicted survival rates.

Clinical significance

Strategies for prolonging the clinical lifetimes of ceramic restorations are proposed based on a crack-containment philosophy.     

Comprehensive Analysis of Repair/Reinforcement Materials for Polymethyl Methacrylate Denture Bases: Mechanical and Dimensional Stability Characteristics

Fracture of complete denture is a common problem as acrylic resins hold inherent limitations. This necessitates affirmation of a selection criterion by evaluating the critical requirements of repair materials. The study intended to evaluate mechanical properties and dimensional stability of common denture base repair and reinforcement materials under standard experimental protocol. Seven types of denture reinforcement materials were chosen. Forty cuboidal samples were made in accordance with ISO 178 for three point bending test and divided to eight groups of five samples each. One group acted as control and samples of seven groups were sectioned and repaired with chosen materials. Five mechanical properties—fracture load, deflection, flexural strength, fracture toughness and elastic modulus were evaluated for all groups. Forty mandibular complete denture specimens were utilized for evaluating fracture load and deflection under loading. Dimensional stability after repair with seven different repair materials was analyzed in two planes (Linear and curvilinear) utilizing separate set of denture samples. Heat cure polymethyl methacrylate with polyethylene fiber was affirmed as material of choice based on this study as it accomplishes the most critical norms of requirement.     

血小板衍化生长因子在铒激光制备的骨缺损愈合过程中的表达研究

目的：探讨不同能量的铒激光切割骨组织骨愈合过程中血小板衍化生长因子（PDGF）的表达情况。方法：选择8只兔子,在兔子的颅盖骨上制备直径2mm的4个圆形骨缺损。激光组：能量100mJ,200mJ,400mJ的铒激光分别制备的骨缺损,对照组：种植手机制备的骨缺损。于术后1周,3周,4周,6周分别处死2只兔子取样本,应用免疫组织化学染色法观察PDGF的表达情况。结果：术后1,3周100m．1激光组平均灰度值与200mJ,400mJ激光组及对照组平均灰度值比较差异有统计学意义（P〈0．05）;术后4,6周激光组之间及与对照组平均灰度值比较差异无统计学意义（P〉0．05）。结论：铒激光制备的骨缺损愈合过程中PDGF的表达较传统种植手机组高,且能量为200mJ时PDGF的表达最高。     

Healing responses following transverse root fracture: a historical review and case reports showing healing with (a) calcified tissue and (b) dense fibrous connective tissue

Background

The understanding and management of transverse intra‐alveolar root fractures has evolved to its current high level of sophistication and clinical success from foundations laid down by histological studies as early as the mid‐nineteenth century.

Significance

The aim of the review was to highlight those earlier histological reports and studies that have contributed to the current understanding of the biological processes involved in the healing of transverse root fractures. Healing of a transverse root fracture by calcified tissue was demonstrated histologically by Howe in 1926, while Boulger in 1928 showed the two other patterns of root fracture healing, namely the interposition of fibrous connective tissue and the interposition of bone and periodontal ligament around both fractured segments. Other major histological reports around that time came from members of the so‐called ‘The Vienna group of Illinois’, who had a significant influence in the development of oral biology worldwide. Other important reports and an experimental study emanated from Germany and Switzerland in the late 30s and early 40s, followed in the 1950s and early 1960s by histological material principally from Sweden, Denmark, France, the USA and Britain. Jens Andreasen and Erik Hjörting‐Hansen's landmark paper in 1967 included new histological reports and a classification of healing responses following transverse root fractures. The expansion of knowledge related to root fractures since that time has been exponential, with major contributions from Scandinavia and several other countries.

Case reports

Accompanying the historical review are two case reports with histology of root fracture healing by (a) calcified tissue and (b) dense fibrous connective tissue. The role of the pulp and the periodontal ligament in the repair process is described and the clinical significance discussed with particular emphasis to diagnosis and orthodontic management.     

Implementing the National Hip Fracture Database: An audit of care

Background

Hip fractures are common injuries in the elderly, with significant associated morbidity and mortality rates. The National Hip Fracture Database (NHFD) was implemented to audit care according to national standards thus improving its clinical and cost-effectiveness.

Patients and methods

We retrospectively examined the care pathway for all hip fractures after its introduction at our centre over 1 year, with an audit of care according to the BOA-BGS ‘Blue Book’ guidelines. Data between the first (period 1: initial audit) and second (period 2: re-audit) six months of the study period were compared.

Results

There were 372 patients (28% male, 72% female) in total with 190 in period 1 and 182 in period 2. For all patients, the median age was 85 years (range 33–101) and the median time to surgery was 24.5 h (1–519.3), with 251 (67.5%) within 36 h. Surgical delay was mainly due to lack of theatre space (37.6%) and medical reasons (54.7%). The median length of stay was 11 days (2–92) and the inpatient mortality rate was 6.2% (23). When comparing the two study periods, there were significantly more patients undergoing falls (p < 0.01) and bone protection (p < 0.01) assessments in period 2. Lack of theatre space was a significantly less common (p < 0.01), with a significantly shorter median time to surgery (p = 0.01) and length of stay (p < 0.01) in period 2. More patients were discharged to rehabilitation units and the mortality rate was non-significantly lower in period 2 (7.4% vs. 5%). The best practice tariff was met in 45.3% and 70.3% (p < 0.001) of patients in periods 1 and 2 respectively providing a total income of £95230.00 (GBP).

Conclusions

Implementing the NHFD has led to an improvement the quality of hip fracture care according to national guidelines. More patients were assessed by an orthogeriatrician, with a shorter time to surgery and length of stay following re-audit. There is potential for an improvement in mortality rates as well as significant financial income for hospitals.