A 3-year clinical evaluation of endodontically treated posterior teeth restored with two different materials using the CEREC AC chair-side system.

STATEMENT OF PROBLEM: The introduction of polymer-infiltrated ceramic network (PICN) materials may provide more options for dentists in restoring short clinical crowns and extensively damaged posterior teeth, but clinical data for their performance are lacking. PURPOSE: The purpose of this clinical study was to compare the 3-year performance and survival rates of PICN material with those of conservative ceramic onlay restorations for endodontically treated posterior teeth using the CEREC AC chair-side system. MATERIAL AND METHODS: A total of 101 onlay restorations of endodontically treated posterior teeth using the CEREC AC chair-side system were provided in 93 participants. The 101 teeth were divided into 2 groups: Vita Enamic group and Vitablocs Mark II group. Using the modified US Public Health Service quality evaluation system, 2 calibrated evaluators examined the performance of the onlay restorations over 3 years. The Kaplan-Meier method was adopted to analyze the survival rate of restorations (α=.05). The log rank test was used to compare the survival rates of the 2 groups. The Fisher exact test was performed to detect differences in the success rates for extensively damaged teeth and short clinical crown restorations between the 2 groups. The Silness and Löe gingival index was also recorded. RESULTS: The restoration survival rates in the 2 groups were 97.0% (Vita Enamic) and 90.7% (Vitablocs Mark II) (P>.05). Five failures were recorded (4.95%). These failures were caused by restoration debonding (60%), ceramic fractures (20%), and tooth fractures (20%). There were no significant differences between the success rates of restoring extensively damaged teeth and short clinical crowns between the 2 groups (P>.05). The periodontal condition of 25% of participants was improved 3 years after the onlay restorations. CONCLUSIONS: Onlay restorations of endodontically treated posterior teeth with Vita Enamic using the CEREC AC chair-side system are clinically promising prosthodontic alternatives, with a survival rate of 97.0% after 3 years. More research is needed to verify the results of this study.

EMMNet: sensor networking for electricity meter monitoring.

Smart sensors are emerging as a promising technology for a large number of application domains. This paper presents a collection of requirements and guidelines that serve as a basis for a general smart sensor architecture to monitor electricity meters. It also presents an electricity meter monitoring network, named EMMNet, comprised of data collectors, data concentrators, hand-held devices, a centralized server, and clients. EMMNet provides long-distance communication capabilities, which make it suitable suitable for complex urban environments. In addition, the operational cost of EMMNet is low, compared with other existing remote meter monitoring systems based on GPRS. A new dynamic tree protocol based on the application requirements which can significantly improve the reliability of the network is also proposed. We are currently conducting tests on five networks and investigating network problems for further improvements. Evaluation results indicate that EMMNet enhances the efficiency and accuracy in the reading, recording, and calibration of electricity meters.