Influence of hydrophilic pre-treatment on resin bonding to zirconia ceramics.

Atmospheric plasma or ultraviolet (UV) treatment alters the surface characteristics of tetragonal zirconia polycrystal (TZP), increasing its hydrophilicity by reducing the contact angle against water to zero. This suggests that such treatment would increase the wettability of bonding resin. The purpose of this study was to determine how increasing the hydrophilicity of TZP through plasma irradiation, UV treatment, or application of ceramic primer affected initial bonding with resin composites. Here, the effect of each pre-treatment on the hydrophilicity of TZP surfaces was determined by evaluating change in shear bond strength. Plasma irradiation, UV, or ceramic primer pre-treatment showed no significant effect on bonding strength between TZP surfaces and resin composites. In addition, alumina blasting yielded no significant increase in bond strength. Plasma irradiation, UV treatment, or ceramic primer pre-treatment did not lead to significant increase in bond strength between TZP and resin composites.

Analysis of dental treatment performed by dental residents at General Dentistry Department of Tokyo Dental College Chiba Hospital over 6 years following introduction of mandatory dental clinical training system.

Six years have passed since the introduction of legislation mandating at least 1 year of clinical training for those who have passed the national dentist examination. To determine whether clinical training has been appropriately implemented at the General Dentistry Department of Tokyo Dental College Chiba Hospital, a managed-type clinical training facility, the number of patients treated and types of dental and dental technical work performed by dental residents trained by the department were summarized and analyzed. The number of patients treated per dental resident increased from 11 in 2006 to 15 in 2011. By treatment type, periodontic treatment was the most frequently performed throughout the study period, followed by endodontic treatment. Conservation treatment, prosthodontic treatment with crowns/bridges, and prosthodontic treatment with dentures were performed at a similar moderate frequency, while oral surgical treatment was performed least frequently throughout the study period. The frequency of periodontic treatment increased slightly, whereas that of endodontic treatment decreased slightly or remained almost unchanged after introduction of the mandatory clinical training system. When the distribution of dental treatment performed at our department was compared with that of dental treatment performed by general dentists across Japan in 2011, our department showed a slightly lower frequency of periodontic treatment and higher frequency of endodontic treatment than the national total, whereas the frequency of other types of treatment was similar between the two populations. These results demonstrated that appropriate clinical training has been provided by our department to meet the purpose of offering dentists the opportunity to acquire the basic diagnostic and treatment abilities that would enable them to provide appropriate treatment for injuries and diseases frequently encountered in daily practice. The study also revealed some problems, such as a decreasing number of residents engaging in dental technical work each year. For additional improvement in the quality of dental clinical training, more analyses are needed to further identify and address potential problems in the system.

Recent trends among dental residents at Tokyo Dental College.

Trends among dental residents at Tokyo Dental College between 2006, at which time clinical residency became mandatory, and 2011 were analyzed and the following results obtained. Almost all the eligible students from our school participated in the orientation seminar on dental residency programs. Although the number varied slightly by year, approximately 70 to 150 students from other schools also participated in these orientation seminars. Almost all the students from our school and 60 to 80% of those from other schools participating in the orientation seminar each year applied to sit the dental residency entrance examination. The number of candidates was highest in 2006 (318) and lowest in 2010 (205) (average: 248), and the applicant-to-seat ratio for residency was 1.59. The examination pass rate was 59.02%. Approximately 10% of the students from other schools were admitted as dental residents.

Matching system within clinical training facilities group of clinical dental training in Tokyo Dental College Chiba Hospital.

Since clinical dental training became mandatory in April 2006, Tokyo Dental College Chiba Hospital has been offering the following two types of training system: 1. a single system, and 2. a clinical training facilities group system. The clinical training facilities group system consists of program B, in which residents are trained in a cooperation-type clinical training facility for 3-4 months, and program C, in which residents are trained in two cooperation-type clinical training facilities for 7-8 months. A matching system within the clinical training facilities group is applied to select and decide on the cooperation-type clinical training facility for residents. In this system, the ranking of resident candidates that a cooperation-type clinical training facility would like to accept, and the ranking of training facilities that candidates choose are matched. The present study investigated the matching system within the clinical training facilities group in 2006, 2007, and 2008. The rate of matching to their third choice was more than 90% in program B and about 80% in program C in each year, suggesting a high matching rate. The percentage of cooperation-type clinical training facilities accepting dental residents dropped due to a decrease in the number of such residents. The distribution of accepted cooperation-type clinical training facilities is concentrated in Chiba Prefecture where our hospital, the management-type clinical training facility, is located, and the neighboring prefectures.

Clinical usefulness of "Isolite Plus" for oral environment of Japanese people.

The recent demand for dental devices which are easier to handle and offer higher levels of reliability and safety has led to the development in the US of Isolite Plus, a new oral support device. When placed in the oral cavity, Isolite Plus enables marking of the surgical field, secures the treatment space, ensures a vacuum, protects the cheek and tongue, assists in opening the mouth, prevents accidental ingestion/aspiration, ensures treatment without contamination and enhances comfort and safety during dental treatment. The present study was carried out to verify whether Isolite Plus can fit well in the mouth of Japanese people and to determine whether it performs adequately. Thirty resident dentists were required to wear Isolite Plus in their mouth and perform mutual simulation training using an air turbine handpiece. After the training, both subjects playing the role of surgeon and those playing the role of patient were asked to complete questionnaires. On the basis of the results, we discuss the clinical usefulness of Isolite Plus in Japanese people. In the present investigation, Isolite Plus was rated slightly better by surgeons than by patients. The supportive functions of the device were judged inadequate due to the poor fit of the mouthpiece portion of the device to subjects' mouth. For the distribution of Isolite Plus in the Japanese market, the mouthpiece portion of the device should be improved so that it can fit the mouth of Japanese people.

Clinical care provided on post-graduate dental clinical training course at Tokyo Dental College Chiba Hospital, Department of General Dentistry.

Number of patients assigned to dental residents, course of treatment and number of various technical tasks performed as described in the Reports on Clinical Training of Dentists published by the Department of General Dentistry, Tokyo Dental College Chiba Hospital since its establishment in 2002 were compared between before (2003-2005) and after (2006-2007) clinical training was made mandatory, and the state of clinical residency evaluated. Number of patients assigned generally increased, and mean number of patients treated by each resident in 2007 (15.08) was approximately 2 times higher than that in 2003 (8.47). Total number of treatments was 1.38 times higher in 2007 than in 2003, and periodontal treatment accounted for approximately 40% of all treatment both before and after clinical training became mandatory. Number of technical tasks in 2004-2007 was less than half the peak in 2003. To further improve clinical training, evaluation and implementation of effective approaches is necessary to secure an adequate number of patients, widen the variety of cases and increase the number of technical tasks.

Influence of surface topography and surface physicochemistry on wettability of zirconia (tetragonal zirconia polycrystal).

Surface modification technologies are available for tetragonal zirconia polycrystal (TZP) to enhance its bioactivity and osseointegration capability. The surface wettability of an implant material is one of the important factors in the process of osseointegration, possibly regulating protein adsorption, and subsequent cell behavior. The aim of this study was to clarify the effect of topographical or physicochemical modification of TZP ceramics on wettability to determine the potential of such treatment in application to implants. Several types of surface topography were produced by alumina blasting and acid etching with hydrofluoric acid; surface physicochemistry was modified with oxygen (O(2)) plasma, ultraviolet (UV) light, or hydrogen peroxide treatment. The obtained specimens were also subjected to storage under various conditions to evaluate their potential to maintain superhydrophilicity. The results showed that surface modification of surface topography or physicochemistry, especially of blast/acid etching as well as O(2) plasma and UV treatment, greatly increased the surface wettability, resulting in superhydrophilicity. X-ray photoelectron spectroscopy revealed that a remarkable decrease in carbon content and the introduction of hydroxyl groups were responsible for the observed superhydrophilicity. Furthermore, superhydrophilicity was maintained, even after immersion in an aqueous solution, an important consideration in the clinical application of this technology.

The effects of three dry-field techniques on intraoral temperature and relative humidity.

BACKGROUND: The authors evaluated the effects of three dry-field techniques (rubber dam, Isolite i2 [Isolite Systems, Santa Barbara, Calif.] and Coolex [APT, Osaka, Japan]) on intraoral temperature and relative humidity (RH), compared with the effects of a nonisolated control on intraoral temperature and RH. METHODS: The authors measured the room's temperature and RH and then placed dry-field devices in five participants' mouths and measured the intraoral temperature and RH for 20 minutes. They then removed the devices or turned off the vacuum system and measured intraoral temperature for an additional five minutes. RESULTS: The authors found no significant differences in either intraoral temperature or RH at any time during the measurement period in the isolated control group (P > .05); the intraoral temperature was more than 30°C and RH was more than 95 percent. On the other hand, the use of dry-field techniques significantly reduced both intraoral temperature and RH when the rubber dam was in place or the vacuums were turned on (P > .05). The intraoral temperature and RH gradually increased after the authors removed the rubber dam or turned off the vacuums. CONCLUSIONS: The results of this study revealed that all three dry-field techniques could reduce both temperature and RH effectively. CLINICAL IMPLICATIONS: Both Isolite i2 and Coolex could provide environments similar to the room conditions used during in vitro specimen preparation for investigating the mechanical properties of dental restorative materials.