The immediate effect of changing mandibular position on the EMG activity of the masseter, temporalis, sternocleidomastoid, and trapezius muscles

This study investigated the immediate effect of changing mandibular position on the electromyographic (EMG) activity of the masseter (MS), temporalis (TM), sternocleidomastoid (SCM) and trapezius (TR) muscles. Thirty-three (33) asymptomatic subjects (16 males and 17 females), ages 23 to 52 were selected. Surface EMG recordings were obtained for all muscles bilaterally with the mandible in a relaxed open position (relaxed) and during maximal voluntary clenching (fullbite) for the following: a non-repositioning appliance (NONREPOS) and repositioning appliance (REPOS). REPOS significantly reduced EMG activity of all muscles bilaterally during fullbite. During relaxation, reduction in EMG activity was only found for TR bilaterally. NONREPOS decreased the EMG activity bilaterally for TM and TR and unilaterally (left) for MS and SCM during fullbite. During relaxation, NONREPOS decreased muscle activity bilaterally for TR and SCM. A unilateral reduction was found for TM (right). These findings suggest that immediate alterations in mandibular position affect the cranio-cervical system. Both mandibular positions tested lowered the EMG activity of masticatory and cervical muscles in the relaxed and fullbite positions. The trapezius muscle was the most responsive to alterations in mandibular position.     

One-year clinical evaluation of a flowable resin liner associated with a microhybrid resin in noncarious cervical lesions

The aim of this study was to compare the clinical performance over 1 year of a microhybrid composite resin for class V restorations both lined and not lined with a flowable composite resin. Nineteen patients having at least two pairs of cervical noncarious lesions under occlusion were enrolled in this study. A total of 38 restorations were placed, half for each group (Single-Bond + Filtek-Flow + Filtek Z250, and Single-Bond + Filtek Z250). Two calibrated operators placed all restorations according to the manufacturers instructions. Two other independent examiners evaluated the restorations at baseline and after a 12-month period according to the USPHS criteria and modified criteria for color match. The classic alpha score was divided into A1 for not detectable and A2 for slightly discernible filling. Statistical analysis was conducted using Fishers exact test and McNemars test (P=0.05). One restoration was lost after 12 months for each group (retention rate 95% for each group). After 12 months, 18 restorations showed a trend towards dark yellowing (color match A2). The use of Filtek Flow as a liner under Filtek Z250 restorations did not improve the clinical performance of class V restorations after 6 and 12 months of evaluation.     

All-ceramic systems: laboratory and clinical performance

Several all-ceramic systems have been developed in dentistry to meet the increased expectations of patients and dentists for highly aesthetic, biocompatible, and long-lasting restorations. However, early bulk fractures or chippings have led the research community to investigate the mechanical performance of the all-ceramic systems. This overview explores the current knowledge of monolithic and bilayer dental all-ceramic systems, addressing composition and processing mechanisms, laboratory and clinical performance, and possible future trends for all-ceramic materials.     

An overview of the current status of national reporting systems for adverse reactions to dental materials

OBJECTIVES: Since all dental materials pose a potential risk to patients and members of the dental team, the post-market monitoring of adverse reactions caused by dental materials should be considered essential. This article reviews the current status of post-market monitoring of adverse reactions to dental materials and highlights some of the issues that arise in trying to establish an evidence base on the characteristics of adverse reactions to dental materials. METHODS: Norway, Sweden and more recently the UK have sought to monitor adverse reactions to dental materials systematically and proactively in an effort to add to the evidence base on the safety of dental materials. Their experiences in undertaking post-market surveillance have been combined in preparing this article. RESULTS: To date the Norwegian, Swedish and the UK projects has received 1268 reports over 11 years, 848 reports over 5.5 years and 1117 reports over 3 years, respectively, relating to adverse reactions seen or experienced by dental personnel and patients. Presently, there are no harmonized criteria for what can be classified as an adverse reaction related to dental materials. Under reporting is a recognised problem and lack of awareness and lack of clarity as to what constitutes an adverse reaction may be contributory factors. A pro-active reporting system takes a considerable time to become established, but can generate a lot of potentially useful information. CONCLUSIONS: There is a need to raise the awareness among dental professionals of the potential for adverse reactions due to dental materials and to develop an internationally accepted system of data gathering that can produce the evidence that reflect the extent, severity and incidence of adverse reactions to dental materials.     

Effect of implant diameter on reliability and failure modes of molar crowns

The reliability and failure modes of molar crowns supported by three different implant-supported designs were tested according to the following groups: group 1, one standard-diameter implant (3.75 mm); group 2, one narrow-diameter implant (3 mm); and group 3, two narrow-diameter implants (3 mm). Loads were applied as mouth-motion cycles using a step-stress accelerated life-testing method. ? values for groups 1 and 3 (1.57 and 2.48, respectively) indicated that fatigue accelerated the failure of both groups, but not for group 2 (0.39). Abutment screw failure was the chief failure mode. Strength and reliability were significantly higher for groups 1 and 3 compared to group 2.     

Effect of implant-supported or retained dentures on masticatory performance: a systematic review

STATEMENT OF PROBLEM: While subjective patient-based measures have been increasingly recognized as critical outcomes for prosthodontic treatment, there continues to be a need to validate for patients what changes in masticatory function can be expected with the provision of new implant-supported or retained dentures. PURPOSE: The purpose of this review was to evaluate the critical factors impacting change in masticatory performance following the provision of new implant-supported or retained dentures. MATERIAL AND METHODS: Information retrieval followed a systematic approach using PubMed and the Cochrane Library. English articles published from 1966 to June 2007, in which the masticatory performance of subjects with implant-supported or retained dentures was assessed by objective methods and compared to performance with conventional dentures, were included. Ratings of the evidence provided in each article followed United States Agency for Healthcare Research and Quality recommendations. RESULTS: From 281 articles identified, 18 peer-reviewed articles met prespecified criteria for inclusion. Specific outcomes of significance identified by these articles rated as level II are: (1) fixed implant-supported partial dentures do not provide significant improvement in masticatory performance compared to conventional removable partial dentures for Kennedy Class I and II partially edentulous mandibles; (2) the combination of a mandibular implant-supported or retained overdenture (IOD) and maxillary conventional complete denture (CD) provides significant improvement in masticatory performance compared to CDs in both the mandible and maxilla for a limited population having persistent functional problems with an existing mandibular CD due to severely resorbed mandible; and (3) the type of implant and attachment system for mandibular IODs has a limited impact. Specific outcomes of significance identified by articles rated as having a moderate level of evidence (level III) are: (1) mandibular fixed implant-supported complete dentures provide significant improvement in masticatory performance compared to mandibular CDs in subjects dissatisfied with their CDs; and (2) implant-supported mandibular resection dentures have an advantage over conventional dentures in masticatory performance on the defect side of the mouth. CONCLUSIONS: Objective benefits in masticatory performance of implant-supported or retained dentures compared to conventional dentures are limited to a mandibular IOD in edentulous patients with a resorbed mandible and/or difficulty adapting to CDs.     

Surgical treatment of oral lymphangiomas with CO₂ laser: report of two uncommon cases

This paper reports the treatment of oral lymphangiomas with carbon dioxide CO? Laser. Lymphangiomas are rare congenital lymphatic malformations. These lesions are most frequently diagnosed during childhood, are most commonly located in the head and neck region, and are extremely rare in the oral cavity. Oral lymphangiomas are of complex treatment due to the difficulty in performing a complete excision. CO? laser is the most often used laser in the oral cavity due to its affinity with water and high absorption by the oral mucosa. Several benefits of the use of CO? laser have been reported for surgical oral procedures. The cases reported herein were biopsy-proven lymphangiomas of the oral cavity. The surgical procedures were carried out under local anesthesia and a focused CO? laser beam (λ10.600 nm, Φ ~2 mm, CW/RSP) was used. At the end of the surgery, the laser beam was used on a defocused mode to promote better hemostasis. Neither sutures nor dressings were used after surgery. No medication and only mouthwashes were prescribed to all patients on the postoperative period. There were no postsurgical complaints from the patients and no relapses of the conditions were observed after follow-up periods of 12 and 18 months. The use of CO? laser was practical, easy to carry out and effective on the treatment of oral lymphangiomas, with no lesion recurrence.     

Clinical evaluation of a nanofilled composite in posterior teeth: 12-month results

This study compared the clinical performance of a nanofilled resin composite for posterior restorations with 2 microhybrid and 1 packable composite after 12 months of clinical service. Forty-two patients with at least 5 Class I or II restorations under occlusion were enrolled in this study. A total of 148 restorations were placed, 25% for each material (Filtek Supreme, Pyramid, Esthet-X or Tetric Ceram). Two calibrated operators placed all restorations, according to the manufacturers' instructions. One week later, the restorations were finished/polished. Two independent examiners evaluated the restorations at baseline and after 12 months according to the USPHS modified criteria. All patients attended the 12-month recall and 148 restorations were evaluated. Friedman repeated measures analysis of variance by rank and Wilcoxon sign-ranked test for pair-wise comparison was used for data analysis (alpha=0.05). All materials showed only minor modifications, and no differences were detected between their performance at baseline and after 12 months. After 1 year, the nanofilled resin composite showed similar performance to the other packable and microhybrid resin composites.