Initial fracture resistance and curing temperature rise of ten contemporary resin-based composites with increasing radiant exposure.

OBJECTIVES: The principal objective of this study was to determine whether the bulk fracture resistance of ten light activated composites varied over a clinically realistic range of radiant exposures between 5 and 40 J/cm(2). METHODS: Ten operators were tested for clinically simulated radiant exposure delivery from a Bluephase(®) (Ivoclar Vivadent, Schaan, Liechtenstein) LED light to an occlusal cavity floor in tooth 27 in a mannequin head using a MARC(®)-Patient Simulator (Bluelight Analytics Inc., Halifax, NS) device. Notch disc test samples were prepared to determine the torque resistance to fracture (T) of the composites. Samples were irradiated with the same monowave Bluephase(®) light for 10s, 20s or 40s at distances of 0mm or 7 mm. After 24h, storage samples were fractured in a universal testing machine and torque to failure was derived. RESULTS: Radiant exposure delivered in the clinical simulation ranged from 14.3% to 69.4% of maximum mean radiant exposure deliverable at 0mm in a MARC(®)-Resin Calibrator (Bluelight Analytics Inc., Halifax, NS) test device. Mean torque to failure increased significantly (P<0.05) with radiant exposure for 8 out of 10 products. The micro-fine hybrid composite Gradia Direct anterior (GC) had the lowest mean (S.D.) T between 10.3 (1.8)N/mm and 13.7 (2.2)N/mm over the tested radiant exposure range. Three heavily filled materials Majesty Posterior, Clearfil APX and Clearfil Photo-Posterior (Kuraray) had mean T values in excess of 25 N/mm following 40 J/cm(2) radiant exposure. Mean T for Z100 (3MESPE) and Esthet-X (Dentsply) increased by 10% and 91% respectively over the tested range of radiant exposures. CONCLUSIONS: Individual products require different levels of radiant exposure to optimize their fracture resistance. Light activated composites vary in the rate at which they attain optimal fracture resistance. CLINICAL SIGNIFICANCE: Unless the clinician accurately controls all the variables associated with energy delivery, there is no way of predicting that acceptable fracture resistance will be achieved intra-orally.

The bond of different post materials to a resin composite cement and a resin composite core material.

PURPOSE: To investigate the bond of endodontic post materials, with and without grit blasting, to a resin composite cement and a core material using push-out bond strength tests. MATERIALS AND METHODS: Fiber-reinforced composite (FRC) posts containing carbon (C) or glass (A) fiber and a steel (S) post were cemented into cylinders of polymerized restorative composite without surface treatment (as controls) and after grit blasting for 8, 16, and 32 seconds. Additional steel post samples were sputter-coated with gold before cementation to prevent chemical interaction with the cement. Cylindrical composite cores were bonded to other samples. After sectioning into discs, bond strengths were determined using push-out testing. Profilometry and electron microscopy were used to assess the effect of grit blasting on surface topography. RESULTS: Mean (standard deviation) bond strength values (MPa) for untreated posts to resin cement were 8.41 (2.80) for C, 9.61(1.88) for A, and 19.90 (3.61) for S. Prolonged grit blasting increased bond strength for FRC posts but produced only a minimal increase for S. After 32 seconds, mean values were 20.65 (4.91) for C, 20.41 (2.93) for A, and 22.97 (2.87) for S. Gold-coated steel samples produced the lowest bond strength value, 7.84 (1.40). Mean bond strengths for untreated posts bonded to composite cores were 6.19 (0.95) for C, 13.22 (1.61) for A, and 8.82 (1.18) for S, and after 32 seconds of grit blasting the values were 17.30 (2.02) for C, 26.47 (3.09) for A, and 20.61 (2.67) for S. FRC materials recorded higher roughness values before and after grit blasting than S. With prolonged grit blasting, roughness increased for A and C, but not for S. CONCLUSIONS: There was no evidence of significant bonding to untreated FRC posts, but significant bonding occurred between untreated steel posts and the resin cement. Increases in the roughness of FRC samples were material dependent and roughening significantly increased bond strength values (p<0.05). Surface roughening of the tested FRC posts is required for effective bonding.

The survival of Class V restorations in general dental practice: part 3, five-year survival.

OBJECTIVE: To evaluate the survival over five years of Class V restorations placed by UK general practitioners, and to identify factors associated with increased longevity. DESIGN: Prospective longitudinal cohort multi-centre study. SETTING: UK general dental practices. MATERIALS AND METHOD: Ten general dental practitioners each placed 100 Class V restorations of varying sizes, using a range of materials and recorded selected clinical information at placement and recall visits. After five years the data were analysed using the Kaplan-Meier method, log-rank tests and Cox regressions models to identify significant associations between the time to restoration failure and different clinical factors. RESULTS: After five years 275/989 restorations had failed (27.8%), with 116 (11.7%) lost to follow-up. Cox regression analysis identified that, in combination, the practitioner, patient age, cavity size, moisture contamination and cavity preparation were found to influence the survival of the restorations. CONCLUSIONS: At least 60.5% of the restorations survived for five years. The time to failure of Class V restorations placed by this group of dentists was reduced in association with the individual practitioner, smaller cavities, glass ionomer restorations, cavities which had not been prepared with a bur, moisture contamination, increasing patient age, cavities confined to dentine and non-carious cavities.

The survival of Class V restorations in general dental practice. Part 2, early failure.

OBJECTIVE: To evaluate Class V restorations placed by UK general practitioners comparing those failing or surviving after two years, and to identify factors associated with early failure. DESIGN: Prospective longitudinal cohort multi-centre study. Setting UK general dental practices. MATERIALS & METHODS: Ten dentists each placed 100 Class V restorations and recorded selected clinical information at placement and recall visits. Univariate associations were assessed between recorded clinical factors and whether restorations had failed or not at two years. Multi-variable binary logistic regression was also undertaken to identify which combination of factors had a significant effect on the probability of early failure. RESULTS: At two years, 156 of 989 restorations had failed (15.8%), with 40 (4%) lost to follow-up. Univariate analysis showed a significant association between restoration failure and increasing patient age, payment method, the treating practitioner, non-carious cavities, cavities involving enamel and dentine, cavity preparation and restoration material. Multi-variable analysis indicated a higher probability of early failure associated with the practitioner, older patients, glass ionomer and flowable composite, bur-preparation and moisture contamination. CONCLUSIONS: Among these practitioners, both analytic methods identified significant associations between early failure of Class V restorations and the practitioner, cavity preparation method, restoration material and patient's age.

The effect of the elastic modulus of endodontic posts on static load failure.

AIM: To compare posts of different flexibility using static load testing. Hypotheses tested were (1) the flexural modulus of endodontic posts does not show a linear relationship with failure load and (2) the flexural modulus of endodontic posts does not show an association with failure mode. METHODOLOGY: Thirty 2 mm diameter rods of a glass fibre material Aesthetiplus (A), a carbon fibre Composipost (C) and stainless steel (S) were cemented into 90 roots of extracted human teeth using resin cement. Composite resin cores were added and the roots embedded in self-curing acrylic resin. Samples were loaded at 90° in a universal testing machine until failure. Failure loads and fracture levels were compared using one-way anova and post-hoc Scheffé tests. Proportions of different failure modes were compared with Chi square tests (α = 0.05). RESULTS: Mean failure loads - MPa (SD) were A - 278.69 (85.79), C - 258.86 (82.05), S - 347.37 (74.50). There was no significant difference in the mean failure load of roots containing the FRC posts (P = 0.639), but it was significantly greater for steel post samples (P < 0.01). The mean level of fracture among the groups was not significantly different (P = 0.879). No root fractures were 'favourable'. Significantly more root fractures and fewer core fractures occurred for group A than for groups C or S (P < 0.01). CONCLUSION: The elastic modulus of an endodontic post does not appear to be a principal factor influencing load at failure or mode of failure of post-restored teeth.

The survival of Class V restorations in general dental practice. Part 1, baseline data.

OBJECTIVE: Evidence on the survival of different restorations in general practice is scarce and so to address this need, a study was designed to monitor the outcome of Class V restorations placed in UK general practices. DESIGN: Prospective longitudinal cohort multi-centre study. SETTING: UK general dental practice. MATERIALS AND METHODS: Ten UK dentists each placed 100 Class V restorations and recorded selected clinical information at placement and at recall visits on record cards. Dentists selected materials and techniques which they felt appropriate to each clinical situation. RESULTS: Data cards for 11 restorations were incorrectly completed or information was missing leaving 989 for analysis. The majority of restorations were placed in patients between 51 and 60 years of age, in canines or premolars (68.4%) and under private contract (63%). Composite (40.85%) and compomer (23.46%) were the most frequently placed materials overall but were not the most frequently placed restorative by some dentists. CONCLUSIONS: Different dentists use different methods to manage Class V lesions but each dentist tends to use one restorative material predominantly. There is a degree of overlap among practitioners in the materials which they employ, but clear preferences were displayed in the materials used and handling techniques.

Morale of vocational dental practitioners in the United Kingdom.

OBJECTIVE: This study was undertaken to devise a suitable survey instrument to measure morale, and to undertake an assessment of morale amongst vocational dental practitioners (VDPs) in the UK. DESIGN: Postal questionnaire survey. SETTING: Dental vocational training schemes in the UK. SUBJECTS: Vocational dental practitioners. METHOD: A confidential postal questionnaire was used to measure levels of morale among all VDPs in the UK in 2007. RESULTS: A response rate of 76.7% was achieved. The mean morale score for Scottish VDPs was significantly higher than that of the Northern Irish VDPs, which in turn was significantly higher than those of the VDPs in England or Wales. In England and Wales females recorded higher morale scores than males. Lowest morale scores were associated with statements referring to concerns about future changes to NHS dentistry, and the limits on treatment within the NHS system. The highest scores were associated with good working relationships. CONCLUSION: The use of an appropriately tested questionnaire has provided a convenient objective measure of morale. The morale of VDPs in the United Kingdom was lower than expected. Scottish VDPs recorded higher morale scores than other VDPs and responded more positively in the survey instrument. The most negative responses from all VDPs were regarding the effect of the NHS system on treatment and concerns about future changes to the NHS.

Teaching posterior composite resin restorations in the United Kingdom and Ireland: consensus views of teachers.

Posterior composite resin restorations are an established feature of contemporary dental practice and all new dental graduates should be competent in providing such treatments for their patients. Surveys of educational curricula in this area in the United Kingdom and Ireland, as well as North America, have demonstrated variations both within and between dental schools. Such inconsistency does not help new dental school graduates, and may lead to confusion. At the British Association of Teachers of Conservative Dentistry Annual Conference held in Birmingham in September 2005, a session was devoted to the development of guidelines for dental schools on teaching posterior composite resin restorations to dental undergraduates. The theme of the conference concerned the teaching implications for changing from amalgam to composite. Two of the principal speakers at the meeting (Joost Roeters and Niek Opdam) were from the dental school at the University of Nijmegen in the Netherlands. This school was the first in Europe to discontinue the use of dental amalgam in its undergraduate curriculum over a decade ago. This paper reports the consensus views of those present on guidelines for teaching posterior composite resin restorations to dental undergraduate students.

Assessing the quality of radiographic processing in general dental practice.

OBJECTIVES: To determine if a commercial device (Vischeck) for monitoring film processing quality was a practical option in general dental practice, and to assess processing quality among a group of GDPs in the West Midlands with this device. DESIGN: Clinical evaluation. SETTING: General dental practice, UK, 2004. METHOD: Ten GDP volunteers from a practice based research group processed Vischeck strips (a) when chemicals were changed, (b) one week later, and (c) immediately before the next change of chemicals. These were compared with strips processed under ideal conditions. Additionally, a series of duplicate radiographs were produced and processed together with Vischeck strips in progressively more dilute developer solutions to compare the change in radiograph quality assessed clinically with that derived from the Vischeck. RESULTS: The Vischeck strips suggested that at the time chosen for change of processing chemicals, eight dentists had been processing films well beyond the point indicated for replacement. Solutions were changed after a wide range of time periods and number of films processed. The calibration of the Vischeck strip correlated closely to a clinical assessment of acceptable film quality. CONCLUSIONS: Vischeck strips are a useful aid to monitoring processing quality in automatic developers in general dental practice. Most of this group of GDPs were using chemicals beyond the point at which diagnostic yield would be affected.

An assessment of career satisfaction among a group of general dental practitioners in Staffordshire.

OBJECTIVES: To assess the level of job satisfaction among general dental practitioners from one area of England, and to assess the association of various personal and work related factors with job satisfaction. DESIGN: Postal questionnaire survey. SETTING: General dental practices in South Staffordshire, Wolverhampton and Dudley, England. METHOD: An anonymous questionnaire posted to all 396 registered dentists in the above areas. RESULTS: A 75% response rate was achieved. Data were analysed using non-parametric statistics for any significant differences in the scores for stress, respect, overall professional satisfaction, quality of life and overall job satisfaction according to the different demographic groupings of the dentists (alpha =0.05). Dentists with an area of special interest had higher scores in all categories except quality of life. Overall job satisfaction was higher among private dentists, and those in group practices and in non-rural locations. The highest bi-variate correlation occurred between overall job satisfaction and overall professional satisfaction, delivery of care, income, respect and professional time. CONCLUSIONS: Job satisfaction was judged to be good among this group. Stress was the factor associated with the greatest dissatisfaction. This survey produced similar results to preceding US studies, and suggests ways of improving job satisfaction.

Thermal changes and cure depths associated with a high intensity light activation unit.

OBJECTIVES: The objectives of this study were to evaluate the thermal emission and curing characteristics of a high intensity halogen light (Astralis 10-Ivoclar Vivadent, Schaan. Leichtenstein) alone and on curing a conventional and a fast-curing micro-hybrid composite. METHODS: A bead thermistor was placed in the base of a standard model cavity. The cavity was irradiated using the light unit whilst empty, and when filled with either composite. Temperature rises were recorded using the light in four different output modes. Further samples were prepared to assess depth of cure via a digital penetrometer, light transmission using a computer-based radiometer, and microhardness with a Wallace hardness tester. RESULTS: Mean peak temperature rises recorded during polymerisation of the composites ranged from 6.9 degrees C for the product InTen-S cured with the Adhesive programme (Adh) to 11.0 degrees C for the product Tetric Ceram HB cured with the High Power (HI P) programme. A significantly greater depth of cure was obtained for InTen-S in line with the greater light transmission obtained for this material. DISCUSSION: The very high thermal emission characteristics reported in a recently published investigation for this light unit were not confirmed. CONCLUSIONS: As the extent of thermal trauma that can be tolerated by the dental pulp is unknown consideration should be given to the choice of light activation unit and curing programme when polymerising light activated resin based restorations in deep cavities close to the pulp.

The incidence of occupational exposures among students in four UK dental schools.

OBJECTIVES: To evaluate: the incidence of occupational exposures (OE) to patient body fluids among a sub-group of dental students; the rate of reporting of incidents; and the association of various factors. DESIGN: Multicentre retrospective analysis. SETTING: Four UK dental schools in 2000. SUBJECTS: Dental students from 4 UK schools completed a confidential questionnaire at the end of the clinical years of their undergraduate course. RESULTS: The response rates ranged from 71-100%, showing that 12-40% of students among the schools had experienced one or more OE incidents since starting their course. No statistically significant association was found between OE incidence and age, sex, dominant hand or time of day; most OE occurred with handling of local anaesthetic syringes. 61-78% of incidents were penetrative in nature, and 28-53% of students had not reported their last OE. OE incidence was associated with school, year of course, presence of patient and presence of an assistant. There were substantial differences in the numbers of students experiencing OE among the schools. CONCLUSIONS: Within the limitations of the survey and variations within the clinical activity of schools, it may be seen that improvements are needed in some schools to reduce cross-infection risks, and increase reporting of incidents. Suggestions are offered which may increase the safety of dental treatment.

Organizing a practice-based research group.

There is an urgent need for more dental research to come from the 'real-life' setting of general practice in order to complement the information arising from laboratory testing and institution-based clinical trials. This paper outlines some of the problems and opportunities encountered in undertaking research in practice, and describes the experiences of one such practice-based research group.

Patients' attitudes to rubber dam.

AIM: The aims of this study were to record patients' views of their experience of RD use in an objective manner, and to evaluate the influence of some personal and clinical factors on patients' opinion. METHODOLOGY: A questionnaire was designed which was then distributed to patients receiving dental treatment under RD by (a) final-year dental students at Birmingham Dental School, and (b) general dental practitioners. Patients completed the confidential questionnaire anonymously after treatment, outside the treatment room. After 100 correctly completed forms were collected from group (a) and 106 from group (b), data were entered into a database and subsequently analyzed using SPSS. Analyses were confined to simple cross-tabulations of the patients' responses and potential associated factors, with chi-square analysis and appropriate follow-up comparisons wherever necessary. RESULTS: In both groups, the majority of patients said they would prefer RD to be used at their next appointment, and most had a positive opinion of the experience. No statistically significant association between age, sex, procedure, application time or duration of use and preference for rubber dam was found. Prolonged RD use showed some association with a negative opinion of the experience of RD. Compared with the dentists, students took longer to apply rubber dam and it was in place for longer. Fewer student patients preferred RD next time, and were less positive about its use than the dentists' patients. CONCLUSIONS: Further evidence is presented that (i) Patients generally are not averse to RD. (ii) Placement of rubber dam does not take long. (iii) Operator experience improves patient compliance.

Occupational exposures occurring in students in a UK dental school.

BACKGROUND: Students whilst training may encounter a number of incidents where infection from patient body fluids may occur, especially as their manual skills are underdeveloped and their clinical experience is limited. PURPOSE OF STUDY: (a) To assess the nature of the occupational exposures occurring to students in a UK dental school, (b) to assess the rate of reporting of incidents, and (c) to evaluate the association of various factors with these exposures. Students in the third, fourth and final years of the 5-year undergraduate dental course at the University of Birmingham were asked to complete a questionnaire that inquired into personal details, number and nature of incidents, their reporting and follow-up. A 100% response rate was achieved. RESULTS: Across the years, there was no significant correlation (p > 0.01) between sex, dominant hand, use of protective glasses or time of day. Slightly more exposures occurred in males, right-handed students, and in the afternoon. A significant decrease in exposures (p < 0.01) occurred within final year, and when an assistant was employed. Significantly more incidents occurred while a patient was being treated than during operational clean-up procedures. A substantial number of dental students had experienced one or more occupational exposures during training. Of these, percutaneous injuries predominated. Junior students appear to be more likely to experience exposures, and in these students, needlestick injuries are the most common source. CONCLUSIONS: To reduce the incidence of these exposures, more instruction and training may be required in the earlier clinical years and more chairside assistance. Improvements are required in the monitoring of post-screening for seroconversion after HBV immunization, and in the reporting of test results in the event of an exposure incident. Under-reporting of incidents is common and ways to encourage and facilitate reporting should be sought.

Non-metal post systems.

For many years metals, whether cast or prefabricated, have been exclusively used to construct posts as foundations for indirect restorations. Developments in composite and ceramic materials have resulted in the introduction of metal-free post systems as alternatives. This article provides an overview of the systems currently available, gives guidance on their use, and discusses some of the principles underlying the clinical performance of posts.

Endodontic standards in general dental practice--a survey in Birmingham, Part I.

A postal questionnaire was used to evaluate endodontic treatment performed in the general dental services in Birmingham, assessing whether practice type--private or National Health Service (UK), or year of graduation, influences compliance with established guidelines. For the aspects of treatment investigated, many dentists were not following guidelines. More private practitioners adhered to the guidelines. Practitioner age was not related to compliance with guidelines, although there were differences in the procedures and materials employed among the different age groups. Within the survey's limits, it was concluded that endodontic performance varies from established guidelines.

Endodontic standards in general dental practice--a survey in Birmingham, UK, Part 2.

A postal questionnaire was used to ascertain the views of practitioners on postgraduate education, and on the way they performed endodontic treatment. Attendance at postgraduate courses was low and was influenced by the style and content of courses as well as financial considerations. Hands-on courses were the preferred mode of delivery for postgraduate education. Most practitioners wished to change the way they carried out their endodontic treatment, and the majority felt this could only occur with an increase in fees.