Strategies to improve quality of life in patients with head and neck cancer: microvascular surgery to nanotechnology

Educational Objectives: 1. Learn selection of microvascular free flaps to improve functional outcome.     

Mechanical Properties of Various Glide Path Preparation Nickel-titanium Rotary Instruments

Introduction

The aim of this study was to compare the cyclic fatigue, torsional resistance, and bending stiffness of single-file glide path preparation nickel-titanium instruments.

髁突骨折55例治疗体会

目的:探讨髁突骨折的治疗方法。方法:回顾性分析55例髁突骨折患者的资料,其中非手术治疗(保守治疗)40人,手术治疗15人,经随访1～5年,观察髁突骨折后成角和恢复情况与远期临床疗效的关系。结果:行保守和手术治疗者的平均髁突骨折移位角度分别为27°和56°,平均年龄分别为23岁和36岁。结论:根据髁突骨折移位角度和年龄来选择保守治疗或手术治疗,其远期效果较好。     

Torsional resistance of retreatment instruments

Introduction

This study compared the torsional resistance of two brands of rotary nickel-titanium (NiTi) instruments indicated for endodontic retreatment.

Methods

Mtwo retreatment instruments #15 and #25 (VDW, Munich, Germany) and ProTaper Universal retreatment instruments D2 and D3 (Maillefer/Dentsply, Ballaigues, Switzerland) were subjected to a torsional assay in clockwise rotation. The two parameters evaluated were maximum torque and angular deflection at failure. Fractured instruments had their fractured surfaces and helical shafts examined by scanning electron microscopy.

Results

The results indicated that the angular deflection at fracture decreased in the following order: Mtwo retreatment file #15 > Mtwo retreatment file #25 > ProTaper Universal retreatment file D2 > ProTaper Universal retreatment file D3. As for the maximum torque values, the results revealed the following descending order: ProTaper Universal file D2 > Mtwo retreatment file #25 > ProTaper Universal file D3 > Mtwo retreatment file #15. Scanning electron microscopic analysis revealed that plastic deformation occurred along the helical shaft of the fractured instruments. Fractured surfaces were of the ductile type.

Conclusions

The instruments tested showed different torsional behavior depending on the parameter evaluated. If one considers that high angular deflection values may serve as a safety factor, then the Mtwo retreatment instruments showed significantly better results.     

Prognostic factors in head and neck ACC

Adenoid cystic carcinomas (ACC) are uncommon head and neck tumors, which present an indolent and slow growth, frequent late distant metastases and low long-term survival rate.     

Enamel-dentin crown fractures bonded with various bonding agents

Abstract A method is described, by which the fracture strength of bonded, previously fractured incisors can be measured. The study employed incisors from sheep, which could be obtained in suitable numbers and with limited variation in size. The incisors were fractured parallel to the incisal edge. The mean fracture area + SD of central incisors was 8.45 ± 0.89 mm² and of lateral incisors 6.50 ± 0.64 mm². The enamel area constituted about 30% of the total fracture area. Acid etching of the enamel and bonding of the fractures with an unfilled resin yielded a fracture strength, which was approximately 38% of the fracture strength of fractured teeth restored with acid etching of enamel, Gluma treatment of dentin and bonding with the unfilled resin. Teeth restored in this way, but using the dentin bonding agent Tenure or Scotchbond2 instead of Gluma, exhibited mean fracture strengths which were not significantly different from that obtained when Gluma was employed as the bonding agent. The mean fracture strength by using one of the three bonding agents in combination with acid etching of enamel was about 8 MPa, which is approximately 50% of the fracture strength of intact teeth.     

Reinforcement of bonded crown fractured incisors with porcelain veneers

Abstract A method is described by which porcelain laminate veneers are used to reinforce crown-fractured incisors which have been restored by reattachment of enamel-dentin fragments using enamel etching and a dentin bonding system. In an experimental model using sheep incisors, it was found that fracture strength equal to that of intact incisors could be achieved by employing this method. This is in contrast to fracture strengths of reattached enamel-dentin tooth fragments without porcelain laminates which were only 50% of intact incisors. It is suggested that porcelain laminate veneers may be used to supplement fragment bonding, thereby enhancing dental esthetics and function.     

Prognosis of root-fractured permanent incisors

Abstract The prognosis of 56 root-fractured permanent incisors was evaluated clinically and radiographically for 2 to 31 years. Information about initial case histories, examination and treatment of root-fractured teeth were recorded retrospectively from patient cards. Most of the-root fractures occurred in the 16–20 year age group (38%) followed by the 11–15 year age group (29%). Males were involved more often than females. Fifty-two percent of the patients visited the dental clinic with in the first week, while 48% did so 1 month-31 years later alter the injury. The leading cause of root fractured injuries was falls (46%) and mostly involved one tooth (71%). Maxillary central incisors were the most often affected teeth (95%). The most common type of root fracture was in the middle third of the root (57%) followed by apical part (34%). About 59% of untreated or splinted teeth maintained their vitality. Healing with connective tissue was observed in 19 teeth, with calcified tissue in 15 teeth and with osseous tissue in only one tooth. There was partial or complete obliteration of the pulp space in these healed cases (62.5%). The formation of pulpal hard tissue produced no additional clinical problems. Partial or total pulp necrosis were noted in 21 (37.5%) teeth. Endodontic treatment was successful in 12 cases. The remaining 9 teeth were extracted due to the loss of marginal alveolar bone and apical periodontitis.     

Fracture toughness of various core build-up materials

PURPOSE: The purpose of this investigation was to compare the fracture toughness of several core materials. MATERIALS AND METHODS: Five core build-up materials were tested: (1) glass ionomer, (2) resin-modified glass ionomer, (3) titanium-reinforced composite, (4) composite resin with fluoride, and (5) amalgam. Fracture toughness determinations were made using 3-point flexure of beams with a central single-edge notch. The notch was standardized by the use of a special mold into which each of the materials was condensed. Ten beams of each material were tested on an Instron test machine (Instron Corp, Canton, MA) at a crosshead speed of 1.25 mm/min. The maximum loads were determined from which the fracture toughness values (KIC) were calculated. The data were analyzed statistically using analysis of variance and t tests. RESULTS: The mean fracture toughness value in MN.m-3/2 for each of them is as follows: (1) glass ionomer, 0.717 +/- 0.071; (2) resin-modified glass ionomer, 0.747 +/- 0.061; (3) titanium-reinforced composite, 1.409 +/- 0.051; (4) composite resin with fluoride, 1.660 +/- 0.086; and (5) amalgam, 1.521 +/- 0.081. There was no significant difference in the KIC values for the glass ionomer-based materials, and both of these were significantly lower than amalgam, titanium-reinforced composite resin, and composite resin with fluoride (p < .001). CONCLUSION: The titanium-reinforced composite resin, the composite resin with fluoride, and amalgam materials showed fracture toughness most likely to withstand the stresses generated during mastication.