Dentists' restorative decision-making and implications for an 'amalgamless' profession. Part 1: a review

Current trends in placing posterior composite restorations: Perspectives from Palestinian general dentists: A questionnair study

Aim

The success of composite restorations relies on material selection and practitioner-related factors that shape the overall outcome. This study explores the practices of Palestinian general dental practitioners in placing posterior composites, examining the impact of work sector, experience, and gender on their choices.

Materials and Methods

The study was conducted as an online cross-sectional questionnaire and involved 351 participants, with a response rate of 69.8%. The survey comprised 18 closed-ended questions covering demographics, material selection, and composite placement in special cases, techniques, and factors influencing the choices. Statistical analyses included descriptive statistics, chi-squared tests, and Fisher's exact tests.

Results

Composite was the predominant choice for small-size (83.7%) and large-size posterior cavities (60.4%). Practitioners commonly opted for composite restorations in cases involving occlusal parafunctional activity (60%), poor oral hygiene (78%), and subgingival cavities (72.2%). Only 19.6% and 5.3% reported occlusal and gingival beveling, respectively. Rubber dams for isolation stood at 30%, one-step self-etch adhesives at 44.9%, and the oblique layering technique at 51%. Light-emitting diode curing units were popular (97.55%), but monitoring output with a radiometer was infrequent (93.5%). Tofflemire metal matrix usage was 46.1%, whereas a sectional matrix system was employed by 29.8%. A 2 mm layer exposure to light curing for 20 s was reported by 62%, and 27.75% utilized additional light-curing postmatrix band removal.

Conclusion

The study highlights the need for Palestinian dental professionals to update their clinical approaches in placing composite restorations in posterior teeth. Gender, work sector, and experience influence practitioners' choices, emphasizing the importance of tailored continuing education programs for improving clinical practices.

Effect of topical fluoride applications on residual monomer release from resin-based restorative materials

BACKGROUND

The effects of topical fluoride applications on the release of monomer ingredients from resin-based dental materials by immersion in various extraction solutions are unclear. The aim of this study was to determine the effect of topical fluorides (APF and NaF) on the elution of residual monomers (Bis-GMA, TEGDMA, UDMA, and HEMA) from resin-based materials.

METHODS

Ninety specimens were prepared, 30 bulk-fill composite resin, 30 nanohybrid universal composite resin, and 30 polyacid-modified composite resin (compomer). These were randomly divided into three groups based on fluoride application procedures. Each specimen was kept in 75% ethanol solution, and residual monomers released from materials were analyzed using high-performance liquid chromatography (HPLC) after 10 min, 1 h, 24 h, and 30 days. The groups were compared using the Mann Whitney U and Kruskal Wallis tests. Measurements were analyzed using the Friedman and Wilcoxon signed-rank tests.

RESULTS

Fluoride applications generally had no considerable effect on the amount of residual monomer released from resin-based restorative materials. The amount of monomer release after topical APF application was similar to the release in the control group and was lower than the release in the NaF group. The release of monomers from the resin-based material used in the study did not approach toxic levels at the applied time intervals. The compomer released lower amounts of monomer than other resin-based materials.

CONCLUSIONS

Fluoride applications do not increase monomer release from resin-based restorative materials. However, compomers should be employed by clinicians due to their lower monomer release compared to other resin restorative materials. The release of monomers from all the resin-based materials did not approach toxic levels at the applied time intervals.

Resin Composite Versus Amalgam Restorations Placed in United States Dental Schools

OBJECTIVES

To investigate the latest teaching policies for posterior resin composite placement versus amalgam and to determine the actual numbers of posterior resin composites versus amalgam restorations placed in American dental schools from 2008 to 2018.

METHODS

Emails were sent to the deans of all 66 dental schools in the United States to collect data in the forms of: 1) Questionnaire on current teaching policies of posterior composite and amalgam restorations; and 2) Data entry form to collect the actual numbers of posterior composite and amalgam restorations placed in their clinics. Descriptive statistics were used to summarize ratios of posterior restorations. Inferential analysis (chi-square test and z-test) was employed to compare posterior restoration proportions over time and within each year. Level of significance was set at 0.05.

RESULTS

For the teaching questionnaire, the response rate was 52% (n=34). Seventy-six per cent of the responding schools reported that they assign 50% or more of their preclinical restorative teaching time towards posterior resin composite placement, while 50% of the responding schools devoted 25% or less towards amalgam teaching. Data entry response rate was 26% (n=17). In 2008, amalgam and resin composite restorations were placed almost equally. However, resin composite restorations were placed significantly more frequently from 2009 onwards in all responding schools. The results revealed a significant ongoing increasing trend in placing posterior resin composites in all responding schools over time (p<0.05).

CONCLUSIONS

Data analysis revealed a clear trend towards an increase in posterior resin composite restoration placement and a decrease in the number of amalgam restorations. However, the time assigned for posterior resin composite teaching is not aligned with quantity of restorations placed. Review and adjustment of the time allocated for teaching and training of each material are suggested.

Composite versus Amalgam Restorations Placed in Canadian Dental Schools

OBJECTIVES

To investigate the latest teaching policies of posterior composite placement versus amalgam and to determine the actual numbers of posterior composites versus amalgam restorations placed in Canadian dental schools, over the years from 2008 to 2018.

METHODS

Emails were sent to Chairs/Heads of Restorative Departments and Clinic Directors of all 10 Canadian dental schools to collect data in the forms of: 1) Questionnaire on current teaching policies of posterior composite and amalgam restorations; 2) data entry form to collect the actual numbers of posterior composite and amalgam restorations placed in their clinics.

RESULTS

For the teaching questionnaire, the response rate was 90% (n=9). Seven (78%) of the responding schools reported that they assign 25%-50% of their preclinical restorative teaching time towards posterior composite placement. While, three (33%) of the responding schools allocated 50%-75% of their restorative teaching towards amalgam placement. Data entry response rate was 80% (n=8). Amalgam material was dominant in the restoration distribution from 2008 to 2012. While from 2013 to 2018, resin composite material was dominant in all eight responding schools. Linear regression analysis revealed a significant increasing trend in placing posterior composites in all the responding schools over time (p<0.05).

CONCLUSIONS

Data analysis revealed a clear trend towards an increase of posterior composite restoration placement and a decrease in the number of amalgam restorations placed. However, the teaching time assigned for posterior composite is not aligned with quantity placed. Review and adjustment of time allocated for teaching and training of each material are recommended.

The Ability of Dental Practitioners to Light-Cure Simulated Restorations

CLINICAL RELEVANCE

Using a patient simulator, dental professionals were tested to determine their ability to light-polymerize simulated restorations in their dental practice. After receiving specific instructions and training using the simulator, their ability to deliver sufficient light to polymerize restorations was significantly and substantially improved.

SUMMARY

Objectives: To determine the ability of dental professionals to deliver a radiant exposure of at least six J/cm2 in 10 seconds to simulated restorations.Methods and Materials: The study initially examined 113 light-emitting-diode (LED) light polymerization units (LPUs) used in dental offices to determine if they could deliver at least 6 J/cm2 radiant exposure (RE) in 10s. This assessment was completed by using a laboratory-grade light measuring device (checkMARC, BlueLight Analytics, Halifax, NS, Canada). The participating dental professionals whose LPUs could deliver 6 J/cm2 then used their own LPU to light-cure simulated anterior and posterior restorations in the MARC Patient Simulator (BlueLight Analytics). They then received specific instructions and were retested using the same LPUs. Data were statistically analyzed with a series of one-way analysis of variance (ANOVA), two-way ANOVA, paired-samples t-tests, Fisher post hoc multiple comparison tests, and McNemar tests with a preset alpha of 0.05 (SPSS Inc).Results: Ten (8.8%) LPUs could not deliver the required RE to the checkMARC in 10s and were eliminated from the study. For the anterior restoration, most dental practitioners (87.3%) could deliver at least 6 J/cm2 before instructions. After receiving additional light-curing instructions, only two (1.9%) participants were unable to deliver 6 J/cm2 to the anterior location. At the posterior location, only 55.3% (57) participants could deliver at least 6 J/cm2 before the instructions. After receiving these instructions, an additional 32 participants delivered at least 6 J/cm2. Overall, after receiving instructions on how to use the LPU correctly, the participants improved the amount of RE they delivered to anterior and posterior restorations by 22.5% and 30%, respectively.Conclusion: This study revealed that at the baseline, 44.7% of participating dental professionals failed to deliver 6 J/cm2 in 10s to the posterior simulated restoration when using their own LPU.

Practice-based analysis of direct posterior dental restorations performed in a public health service: Retrospective long-term survival in Brazil

The aim of this retrospective study was to evaluate the survival and associated factors for the longevity of direct posterior restorations and to verify whether the geographic location of public health units could influence the long-term survival of such restorations. Data were extracted from electronic patient files of the Brazilian public oral health services. The sample comprised 2,405 class I and II restorations performed 4 to 24 years ago (mean, 8.9 years) in 351 patients (6.8 teeth/patient) across 12 public health units located in different city regions (42 professionals—55 restorations). The restoration was considered successful if it had not been repaired or replaced at the time of evaluation; failure was defined as replacement of the restoration, the need for endodontic treatment, tooth/restoration fracture or tooth extraction. Data were analyzed using the Kaplan-Meier test for restoration survival and Cox regression to evaluate the factors associated with failure. The majority of the restorations involved the use of amalgam (85%), involved a single face (70%), and were without pulp/dentin capping (85%). The overall survival rate was 95%, and the mean observation time was 8.9 years. The restoration survival was 79% (95% CI: 60.6–89.5) over 24 years, and the mean survival time was 22.2 years (95% CI: 21.9–22.6 years). The annual failure rate up to 24 years was 0.9%. After the adjustment, only the number of restored faces and the geographic location where the restoration was performed remained associated with failure of the restoration. The direct posterior restorations performed at the evaluated public health service units presented high survival rates. The restorations of people with lower access to POHS had lower survival rates. Class I restorations presented higher survival rates than class II restorations with two or more faces, regardless of the restorative material used.

Managing the phase-down of amalgam amongst Nigerian dental professionals and students: A national survey

BACKGROUND

Amalgam is one of the most reliable dental restorative materials. Health and environmental concerns associated with the mercury content of amalgam have necessitated an amalgam phase-down in clinical practice.

OBJECTIVES

This study investigated the level of awareness and preparedness for the planned amalgam phase-down recommended by the Minamata Convention amongst Nigerian dental students and dentists.

METHODS

This cross-sectional national survey was performed across all geopolitical zones of Nigeria. Data regarding awareness, practice and level of preparedness for amalgam phase-down were obtained using a questionnaire that was distributed amongst clinical dental students and dentists of different cadres, who routinely place dental restorations, in public and private practice. The questionnaires were administered online or were hand delivered. Data were analysed using the chi-square test and Spearman's rank correlation coefficient. A p value ≤ 0.05 was considered statistically significant.

RESULTS

Notably, 845 dental students and dentists participated in the survey. Mean age (±standard deviation) of participants was 30.15 ± 7.67 years, 33.8% were students, and 66.2% were dentists (most dentists [77.1%] were employed at public hospitals). A significant percentage of respondents had poor knowledge of the Minamata Convention (87.7%) and lacked training in the use of alternatives to amalgam (72.0%). Amalgam continues to be commonly used by 39.1% and 31.3% of dental students and dentists, respectively. Only 4.7% of the respondents admitted to following good amalgam phase-down practices. Awareness (P = 0.013) and amalgam phase-down practices (P = 0.011) were significantly higher amongst dentists than amongst dental students.

CONCLUSION

We observed low levels of awareness regarding the Minamata Convention, amalgam phase-down, mercury hygiene practices and training in alternatives to amalgam use amongst Nigerian dental professionals and students.

Dental educators' attitudes towards the teaching of dental amalgam

OBJECTIVE

To ascertain dental educators' attitudes towards the teaching of dental amalgam at dental schools in Australia and identify preferred curricular approaches in a potentially "amalgamless" profession.

METHODS

A mixed methods analysis was employed based on an open-ended response survey followed by a closed-ended questionnaire. Identification of key issues from the survey helped frame the questionnaire. Participants included those with expertise in operative and restorative dentistry, with direct involvement in curriculum development or delivery, at Australian dental schools.

RESULTS

Participants numbered fifteen and represented seven of the nine dental schools in Australia. Key themes identified and explored included the following: (in)consistency of approach to teaching restorative dentistry; a perceived disconnect between undergraduate study and the "real world"; a need for a focus on teaching of alternatives to dental amalgam (80 per cent (strongly) agreeing); the contradictory nature of the evidence base and literature that is not readily understood; the need for more post-graduate education relating to adhesive restorative materials (86 per cent (strongly) agreeing); the need for dental amalgam to continue to be available; formal understandings (guidelines) as to the use of dental amalgam; dental schools in Australia being heard on these issues; and the relevance of this issue (100 per cent (strongly) agreeing the issue is topical and important).

CONCLUSION

There is a broad consensus of dental educators at Australian dental schools as how best to approach the teaching of amalgam if a phase-down is to occur and the issues any such approach may face.

Fluorescence-aided selective removal of resin-based composite restorative materials: An in vitro comparative study

AIM

During removal of resin-based composite (RBC) restorations, removal of adjacent sound tooth structure can easily occur. The aim of the study was to compare the fluorescence-aided identification of restorations (FAIR) method with the conventional method (CM) using white light illumination for the selective removal of tooth-colored RBC restorations.

MATERIALS AND METHODS

Sixty extracted teeth were used to prepare 15 sets of models, each with four teeth. Cavities were prepared in each tooth and a digital three-dimensional scan of each model was taken in STL format. The teeth were then restored with either Admira Fusion, GRADIA DIRECT X, or TPH Spectra LV (20 teeth for each). Five dentists removed the restorations from sets of 12 teeth (six each using FAIR, and six using CM). From a postoperative scan, changes in intercuspal cavity width were measured using the 3D tool CAD software.

RESULTS

Using FAIR, changes in cavity width were not significant (P = .17), and there was no significant interoperator variance (P = .3). In contrast, when using CM, there was a significant increase in cavity width (P = .0025), and considerable interoperator variance (P = .03). FAIR allowed faster completion of the task of restoration removal (average time 100.23 seconds, vs 165.13 seconds from CM).

CONCLUSION

The FAIR method facilitates the selective removal of tooth-colored RBC restorations, with reduced time and less inadvertent removal of sound tooth structure.

CLINICAL SIGNIFICANCE

By enhancing the differentiation between the restorative material and adjacent tooth structure, the FAIR method facilitates removal of tooth-colored restorations, while concurrently prevents unnecessary removal of healthy tooth structure. The same approach may have applications for removal of resin-based materials such as resin cements under restorations, resin fissure sealants, and orthodontic brackets bonding resins.

Direct Posterior Restorations: A 13-Year Survey of Teaching Trends and Use of Materials

Objective:

The study aimed to evaluate teaching trends and use of materials in direct posterior restorations during a 13-year period in an Israeli dental school.

Methods:

Data registered in computerized files, relating to posterior restorations performed in the student clinic during the past 13 years (2004-2016), were collected. The restorative materials used (ie, amalgam vs composite), the type of tooth, and the number of surfaces restored were analyzed.

Results:

Data analysis included 26,925 restorations performed during 13 years. The number of one-surface composite restorations increased from 54.7% (n=330) to 81.9% (n=873). Two-surface restorations increased from 33.3% (n=254) to 64.3% (n=721). The percentage of amalgam restorations in three-surface restorations decreased from 72.08% to 51.34% (n=173). Analysis of tooth type showed that in 2016, the number of composite restorations performed in premolars reached 80.87% (n=723) and in molars 63.50% (n=1035). The percentage of composite restorations in the mandible and the maxilla was virtually equal.

Conclusions:

A clear trend in favor of composite resin restorations is evident in the 13-year survey and suggests a move toward an amalgam-free era.

Has the implementation of the Minamata convention had an impact on the practice of operative dentistry in Jordan?

Objective

To assess Jordanian dentists’ current perception and attitudes towards amalgam and composite restorations four years after the Minamata treaty was endorsed and suggest decision making factors that may influence the type of restoration requested by patients.

Methods

The cross-sectional study was conducted through structured questionnaires distributed to dentists in Amman, Jordan from June 2017 to February 2018.

Results

Of the 1686 dentists who were contacted 758 dentists (response rate 45%) responded to the questionnaire either by email or via field visits. Jordanian dentists used more composite restorations than amalgam. Recurrent caries followed by fracture of the restoration were the main reasons for replacement of both fillings by dentists. However, dentists suggested that the main reason patients requested replacement of amalgam was for ‘staining’. In addition, a large proportion of the dentists had experienced patients who had asked either for replacement of amalgam (77%) or refused an amalgam filling (99%) for aesthetic reasons. In the opinion of the dentists, only 20% patients requested replacement of amalgam because of the mercury content.

Conclusion

The findings of this survey suggest that a ‘phase-down’ of dental amalgam is being implemented in Jordan's dental clinics but it is not associated with commitment to the Minamata Convention, rather to current dental practice trends and patients’ aesthetic demands.

Polymer-based dental filling materials placed during pregnancy and risk to the foetus

Background

Tooth-coloured polymer-based dental filling materials are currently the first choice for dental restorative treatment in many countries. However, there are some concerns about their safety. It has been shown that substances known as endocrine disrupters, which might pass through the placental barrier, are released from these materials within the first hours after curing. Thus, the placement of polymer-based dental fillings in pregnant women may put the vulnerable foetus at risk. Large epidemiological studies exploring the risk of having polymer-based dental materials placed during pregnancy are lacking. The aim of this study was to investigate the association between the placement of polymer-based dental fillings during pregnancy and adverse birth outcomes.

Methods

This study is based on data from the large Norwegian Mother and Child Cohort Study (MoBa). The information about dental treatment during pregnancy was obtained from questionnaires sent to the participating women during weeks 17 and 30 of pregnancy. Reported placement of “white fillings” was used as exposure marker for having received polymer-based dental filling materials. Only singleton births were included in the present study. Data were linked to the Medical Birth Registry of Norway. Logistic regression models that included the mother’s age, level of education, body mass index, parity, and smoking and alcohol consumption during pregnancy were used to estimate the odds ratio (OR) and 95% confidence interval (CI). Different adverse birth outcomes were of interest in the present study.

Results

Valid data were available from 90,886 pregnancies. Dentist consultation during pregnancy was reported by 33,727 women, 10,972 of whom had white fillings placed. The adjusted logistic regression models showed no statistically significant association between having white dental fillings placed during pregnancy and stillbirth, malformations, preterm births, and low or high birth weight.

Conclusions

In this study, women who reported white fillings placed during pregnancy had no increased risk for adverse birth outcomes compared with women who did not consult a dentist during pregnancy. Thus, our findings do not support the hypothesis of an association between placement of polymer-based fillings during pregnancy and adverse birth outcomes.

Evaluation of chromatic changes of a nanocomposite resin using the new whitness index

Background and aims

To evaluate the staining effects of two brands of coffee and the bleaching efficiency of two in-office bleaching methods, upon different opacities of a commercial nanocomposite.

Methods

Twenty four specimens of each opacity, A3 Dentin, A3 Body and A3 Enamel, were fabricated from Filtek Supreme (3MEspe). The specimens were further divided into two groups (n=12) and were immersed in two coffee solutions (Bio Organic Coffee Bellarom, 100% Arabica, and Iulius Meinl Coffee), for 24 hours. Between the staining sessions, the specimens were stored in sterile water, at 37°C. Each group was further divided into three (n=4), in order to be bleached, as follows: Group 1 - Beyond 35% in office, for 4 applications of 15 minutes each, Group 2 – Zoom Day White 6% in office, for 4 applications of 15 minutes each, Group 3 – Control Group, stored in sterile water. Color values were measured with a dental spectrophotometer Vita EasyShade 4.0 and five measurements were recorded for each sample at a time. Lightness L*, color coordinates a* and b* were recorded, at baseline, after staining in coffee and after bleaching. Whiteness index (WID) of the three composite resins (A3D, A3B, A3E) in the three moments were calculated, as well as the color difference Delta E* correspondent to the staining and bleaching process. Data were analyzed using one-way repeated measures ANOVA and the WID index was calculated WID (p<0.05). Univariate analysis of variance was performed for assessing the influence of staining solution upon composite resins, as well as for testing the effect of bleaching agents. The significance level was set at α=0.05 and pairwise comparisons were adjusted by the Least Significant Difference method.

Results

The pairwise comparisons showed no significant difference between the effects of the two bleaching agents upon the WID, meaning that they induce almost similar color changes. The results of the univariate ANOVA test indicated a significant effect of the composite resin and the staining solution upon the WID (p<0.05). However, no significant interaction effect was found between the composite resin and the staining solution (p=0.095). There was a significant difference in the staining effect of the two coffee solutions only for A3B and A3E composite resins (p<0.05).

Conclusions

The chromatic changes of the nanocomposite resin could be evaluated by the variation of the whiteness index. The staining effect induced by the two types of coffee was similar. The most effective protocol was the in-office bleaching method based on Beyond 35%.

The Use of Restorative Materials in Primary Molars among Pediatric Dentists in Israel

OBJECTIVES

To assess the current choice of various restoration materials among Israeli pediatric dentists according to seniority and specialty.

STUDY DESIGN

Participating dentists completed a 23-item questionnaire on their qualifications, type of practice and preference of restorative material.

RESULTS

Seventy-five dentists (average age 46.27±12.6 years, 58 females) participated. Forty-one were specialist pediatric dentists and 34 were general practitioners. Amalgam was preferred by 49.3%, followed by composite (41.3%), glass ionomer cement (5.3%) and compomer (4%). Only 13.3% of the dentists thought amalgam bears environmental and health hazards, compared to 49.3% for composite. Satisfaction was high for amalgam and composite, less for glass ionomer cements and least for compomer. General practitioners preferred amalgam (70.6%) while pediatric dentists preferred composite (51.2%), P < 0.003.

CONCLUSIONS

Amalgam and composite were the materials of choice among the participating Israeli dentists. Most of them (86.7%) responded that amalgam does not possess any health issues. Their satisfaction with the restoration materials was highest for amalgam and composite, a choice significantly affected by whether they were in general practice (amalgam) or specialized in pediatric dentistry (composite).

Dentists' restorative decision-making and implications for an 'amalgamless' profession. Part 4: clinical factor

BACKGROUND

The Minamata Convention embodies a worldwide reduction in the production and use of mercury and mercury-containing products and processes, including a phase-down of dental amalgam. This will change the approach to the use of direct restorative materials in the near future. There is little research as to the influence of clinical factors on dentists' decision-making which may be of use when determining the impact of any change.

METHODS

An online survey relating to aspects of and attitudes to the use of direct restorative materials was distributed to all dentists who were members of the Australian Dental Association and/or members or fellows of the Royal Australasian College of Dental Surgeons. Data were statistically analysed.

RESULTS

There were 408 respondents to the survey. Eighty-seven per cent of respondents (strongly) disagreed that amalgam was a technically more difficult material to place compared with resin composite, 82% (strongly) disagreed that placement time for amalgam was longer than that for resin composite and 69% (strongly) disagreed that amalgam was more difficult to finish than resin composite. Eighty-three per cent of respondents stated they were confident in their ability to place amalgam restorations. Where physical properties were of importance, indirect restorations were preferred (e.g. parafunction) 54%. The factors considered most important when choosing a direct restorative material included moisture control and aesthetics; least important factors were cost and time to place.

CONCLUSIONS

There is consensus that amalgam is not more technically difficult to use, place or finish than resin composite and vice versa. There is recognition that both amalgam and resin composite have limitations in terms of physical properties. When choosing a direct restorative material, clinical factors considered to be of greatest importance are moisture control, aesthetics and the need to apply minimally invasive approaches. There is little difference in the opinions of users and non-users of amalgam with respect to these findings.

The Use of Restorative Materials in Primary Molars among Pediatric Dentists in Israel

OBJECTIVES

To assess the current choice of various restoration materials among Israeli pediatric dentists according to seniority and specialty.

STUDY DESIGN

Participating dentists completed a 23-item questionnaire on their qualifications, type of practice and preference of restorative material.

RESULTS

Seventy-five dentists (average age 46.27±12.6 years, 58 females) participated. Forty-one were specialist pediatric dentists and 34 were general practitioners. Amalgam was preferred by 49.3%, followed by composite (41.3%), glass ionomer cement (5.3%) and compomer (4%). Only 13.3% of the dentists thought amalgam bears environmental and health hazards, compared to 49.3% for composite. Satisfaction was high for amalgam and composite, less for glass ionomer cements and least for compomer. General practitioners preferred amalgam (70.6%) while pediatric dentists preferred composite (51.2%), P < 0.003.

CONCLUSIONS

Amalgam and composite were the materials of choice among the participating Israeli dentists. Most of them (86.7%) responded that amalgam does not possess any health issues. Their satisfaction with the restoration materials was highest for amalgam and composite, a choice significantly affected by whether they were in general practice (amalgam) or specialized in pediatric dentistry (composite).

Mercury Amalgam Diffusion in Human Teeth Probed Using Femtosecond LIBS

In this work the diffusion of mercury and other elements from amalgam tooth restorations through the surrounding dental tissue (dentin) was evaluated using femtosecond laser-induced breakdown spectroscopy (fs-LIBS). To achieve this, seven deciduous and eight permanent extracted human molar teeth with occlusal amalgam restorations were half-sectioned and analyzed using pulses from a femtosecond laser. The measurements were performed from the amalgam restoration along the amalgam/dentin interface to the apical direction. It was possible to observe the presence of metallic elements (silver, mercury, copper and tin) emission lines, as well as dental constituent ones, providing fingerprints of each material and comparable data for checking the consistence of the results. It was also shown that the elements penetration depth values in each tooth are usually similar and consistent, for both deciduous and permanent teeth, indicating that all the metals diffuse into the dentin by the same mechanism. We propose that this diffusion mechanism is mainly through liquid dragging inside the dentin tubules. The mercury diffused further in permanent teeth than in deciduous teeth, probably due to the longer diffusion times due to the age of the restorations. It was possible to conclude that the proposed femtosecond-LIBS system can detect the presence of metals in the dental tissue, among the tooth constituent elements, and map the distribution of endogenous and exogenous chemical elements, with a spatial resolution that can be brought under 100 µm.

Failure of single-unit restorations on root filled posterior teeth: a systematic review

This systematic review investigated the failure rate of conventional single-unit restorations in root filled posterior permanent teeth. Two reviewers independently applied eligibility criteria, extracted data and assessed the quality of the evidence of each included study according to the Cochrane Collaboration's procedures for randomized control trials (RCTs) and the STROBE criteria for observational studies. The MEDLINE (via Ovid), EMBASE (via Ovid), Cochrane Oral Health Group Trials Register and CENTRAL (via Cochrane Library) databases were searched electronically (January 1993 to week 1, February 2015). This was complemented by an additional hand search of selected journals and the references of relevant studies. Clinical studies published on root filled single-unit restorative treatments with a mean follow-up period of at least 3 years were selected. The outcome measured was clinical or radiological failure. Overall, the four RCTs and the single observational study included were of low and high quality, respectively. Therefore, a meta-analysis was not possible. The pooled mean failure rates were reported according to the type of treatment and remaining coronal tooth structure. The current evidence suggested that the failure rates of the treatments may depend on the amount of remaining tooth structure and type of treatment. Post-retained crowns were associated with the most favourable outcome in teeth with one to two remaining coronal tooth wall(s), whereas post-free crowns were superior when greater tooth structure was available. Restorations in teeth without ferrules had such a high rate of failure that other treatment options should be considered.

Balancing the risks and benefits associated with cosmetic dentistry - a joint statement by UK specialist dental societies

Cosmetic dentistry has become increasingly popular, largely as a result of social trends and increased media coverage. This understandable desire for the alleged 'perfect smile' needs to be tempered with an appropriate awareness of the significant risks associated with invasive cosmetic procedures such as veneers and crowns. Patients need to be properly informed that elective removal of healthy enamel and dentine can result in pulpal injury and poorer periodontal health in the longer term, particularly if they are young. The duty of candour means that they ought to be informed that aggressive reduction of sound tooth tissue is not biologically neutral and results in structural weakening of their teeth. Less invasive procedures such as bleaching on its own or for example, combined with direct resin composite bonding, can satisfy many patient's demands, while still being kinder to teeth and having much better fall-back positions for their future requirements. It is the opinion of the British Endodontic Society, British Society for Restorative Dentistry, Restorative Dentistry UK, Dental Trauma UK, British Society of Prosthodontics and the British Society of Paediatric Dentistry that elective invasive cosmetic dental treatments can result in great benefit to patients, but that some aggressive treatments used to achieve them can produce significant morbidities in teeth which were previously healthy. This is a worrying and growing problem with many ethical, legal and biologic aspects, but many adverse outcomes for patients who request cosmetic dental improvements are preventable by using biologically safer initial approaches to treatment planning and its provision.

One-step partial or complete caries removal and bonding with antibacterial or traditional self-etch adhesives: study protocol for a randomized controlled trial

BACKGROUND

Current concepts in conservative dentistry advocate minimally invasive dentistry and pulp vitality preservation. Moreover, complete removal of carious dentin in deep carious lesions often leads to pulp exposure and root canal treatment, despite the absence of irreversible pulp inflammation. For years, partial caries removal has been performed on primary teeth, but little evidence supports its effectiveness for permanent teeth. Furthermore, the recent development of new antibacterial adhesive systems could be interesting in the treatment of such lesions. The objectives of this study are to compare the effectiveness of partial versus complete carious dentin removal in deep lesions (primary objective) and the use of an antibacterial versus a traditional two-step self-etch adhesive system (main secondary objective).

METHODS/DESIGN

The DEep CAries Treatment (DECAT) study protocol is a multicenter, randomized, controlled superiority trial comparing partial versus complete caries removal followed by adhesive restoration. The minimum sample size required is 464 patients. Two successive randomizations will be performed (allocation ratio 1:1): the first for the type of excavation (partial versus complete) and the second (if no root canal treatment is required) for the type of adhesive (antibacterial versus traditional). For the two objectives, the outcome is the success of the treatment after 1 year, measured according to a composite outcome of five FDI criteria: material fracture and retention, marginal adaptation, radiographic examination (including apical pathologies), postoperative sensitivity and tooth vitality, and carious lesion recurrence.

DISCUSSION

The study will investigate the interest of a conservative approach for the management of deep carious lesions in terms of dentin excavation and bioactive adhesive systems. The results may help practitioners achieve the most efficient restorative procedure to maintain pulp vitality and increase the restoration longevity.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier NCT02286388 . Registered in November 2014.

Effect of Instrument Lubricants on the Surface Degree of Conversion and Crosslinking Density of Nanocomposites

PURPOSE

The surface degree of conversion and crosslink density of composites should not be affected by the use of instrument lubricants in order to provide long-lasting tooth restorations. This study aimed to analyze the effect of instrument lubricants on the degree of conversion and crosslink density of nanocomposites.

MATERIALS AND METHODS

Samples (N = 10) were fabricated according to the composites (Filtek Z350 XT, 3M ESPE, St. Paul, MN, USA; and IPS Empress Direct, Ivoclar Vivadent AG, Schaan, Liechtenstein and lubricants used (Adper Single Bond 2 and Scotchbond Multi-Purpose bonding agent adhesive systems, 3M ESPE; 70% ethanol, absolute ethanol, and no lubricant). Single composite increments were inserted into a Teflon mold using the same dental instrument. The composite surface was then modeled using a brush wiped with each adhesive system and a spatula wiped with each ethanol. The control group was fabricated with no additional modeling. The surface degree of conversion and crosslink density were measured by Fourier transform infrared spectroscopy and the hardness decrease test, respectively. Data were analyzed using two-way analysis of variance and the Tukey's test (p < 0.05).

RESULTS

Filtek Z350 XT showed statistically similar degree of conversion regardless of the lubricant used, whereas the use of adhesive systems and 70% ethanol decreased the degree of conversion for IPS Empress Direct. Only Scotchbond Multi-Purpose bonding agent decreased crosslink density for Filtek Z350 XT, whereas both adhesive systems decreased crosslink density for IPS Empress Direct.

CONCLUSION

Filtek Z350 XT appeared to be less sensitive to the effects of lubricants, and absolute ethanol did not affect the degree of conversion and crosslink density of the nanocomposites tested.

CLINICAL SIGNIFICANCE

Although the use of lubricants may be recommended to minimize the stickiness of dental instruments and composite resin, dentists should choose materials that do not have a negative effect on the surface properties of composites. Only the use of absolute ethanol safely maintains the surface integrity of nanocomposites in comparison with adhesive system and 70% ethanol.