Objective To observe the porcelain treated with Nd∶YAG laser irradiation and hydrofluoric acid (HF), and to explore the influence of integrated treatment of Nd ∶ YAG laser irradiation and HF etching in the bond strength of brackets to porcelain.Methods 48 metal ceramic prostheses were randomly divided into untreated control group,HF group,grooved treatment group,0.75W laser group,1.05W laser group,1.45W laser group. All samples were bonded to the brackets.After temperature cycling test,the shear bond strength (SBS)and tensile bond strength (TBS)were measured.Results There were significant differences in SBS and TBS between various surface treatment groups and untreated control group (P < 0.01).The SBS and TBS of brackets bonded in HF group was significantly higher than those in 1.05W laser and 1.45W laser groups (P <0.05).The SBS and TBS in 1.05W laser and 1.45W laser groups were higher than those in HF group (P <0.05).The SBS and TBS in 1.05W laser group were higher than those in other groups (P < 0.05).SBS showed positive correlation with TBS (r =0.426,P =0.000).Conclusion The use of Nd∶YAG laser irradiation with the energy parameter of 1.05W and HF could increase the bonding with formation of composite resin,and the more SBS,the more TBS.

OBJECTIVEThis study aims to analyze the biomechanical effects of four sutures that are related to maxillary growth during a maxillary protraction treatment cycle based on labiolingual appliance.

METHODSA three-dimensional simulation of labiolingual appliance was performed based on a three-dimensional finite-element maxillofacial model combined with solid-modeled sutures.

RESULTSThe displacement and stress distributions were calculated. The labiolingual appliance was suitable for patients with underbites or deep overbites. Sutura frontomaxillaris and sutura zygomaticomaxillaris were vital to the forward displacement and counterclockwise rotation of the maxillary. The changes in sutura zygomaticotemporalis and sutura palatine were not significant.

CONCLUSIONThe influences of the labiolingual appliance on the sutures during the treatment cycle of maxillary protraction can be effectively simulated by the three-dimensional finite-element maxillofacial model.

Biomechanical Phenomena ; Cranial Sutures ; Finite Element Analysis ; Humans ; Imaging, Three-Dimensional ; Malocclusion, Angle Class III ; Maxilla ; growth & development ; Orthodontic Appliances ; Skull

Background:The prognostic values of staging parameters require continual re?assessment amid changes in diag?nostic and therapeutic methods. This study aimed to identify the prognostic factors and failure patterns of non?meta?static nasopharyngeal carcinoma (NPC) in the intensity?modulated radiotherapy (IMRT) era. Methods:We reviewed the data from 749 patients with newly diagnosed, biopsy?proven, non?metastatic NPC in our cancer center (South China, an NPC endemic area) between January 2003 and December 2007. All patients under?went magnetic resonance imaging (MRI) before receiving IMRT. The actuarial survival rates were estimated using the Kaplan–Meier method, and survival curves were compared using the log?rank test. Multivariate analyses with the Cox proportional hazards model were used to test for the independent prognostic factors by backward eliminating insigniifcant explanatory variables. Results:The 5?year occurrence rates of local failure, regional failure, locoregional failure, and distant failure were 5.4, 3.0, 7.4, and 17.4%, respectively. The 5?year survival rates were as follows: local relapse?free survival, 94.6%; nodal relapse?free survival, 97.0%; distant metastasis?free survival, 82.6%; disease?free survival, 75.1%; and overall survival, 82.0%. Multivariate Cox regression analysis revealed that orbit involvement was the only signiifcant prognostic fac?tor for local failure (P=0.011). Parapharyngeal tumor extension, retropharyngeal lymph node involvement, and the laterality, longest diameter, and Ho’s location of the cervical lymph nodes were signiifcant prognostic factors for both distant failure and disease failure (allP<0.05). Intracranial extension had signiifcant prognostic value for distant failure (P=0.040). Conclusions:The key failure pattern for NPC was distant metastasis in the IMRT era. With changes in diagnostic and therapeutic technologies as well as treatment modalities, the signiifcant prognostic parameters for local control have also been altered substantially.