State-of-the-art techniques in operative dentistry: contemporary teaching of posterior composites in UK and Irish dental schools

Proximal contact tightness of direct Class II composite resin restorations with various matrix systems: A systematic review

Background

Restoring an ideal proximal contact in direct Class II composite resin restorations is challenging due to polymerization shrinkage, absence of condensability of composite materials, thickness of matrix bands, and the use of various separation techniques, retainers, and bands.

Aims

The aim of this study was to evaluate the proximal contact tightness that is achieved by various matrix systems used to restore a direct Class II cavity with composite resin restoration.

Methods

A systematic review was carried out according to the PRISMA 2020 statement guidelines. The online search for the articles was done in electronic databases of MEDLINE/PubMed, Cochrane, and Google Scholar. The articles comparing different matrix systems for restoration were selected. Out of 146 articles, a total of 6 articles met the selection criteria and were included. The QUIN risk-of-bias (RoB) tool was used for assessing the study quality. The data extracted from full text articles selected for inclusion, using a standardized software (Office Excel 2013 Software, Microsoft Corporation, Redmond, WA, USA).

Results and Conclusion

Combination of sectional matrices and separation rings resulted in tighter proximal contact compared to other matrix systems.

Effects of silane coupling treatment on the clinical performance of direct repaired resin-based composite (RBC) restorations with or without prior surface sandblasting: A randomized controlled trial

OBJECTIVE

To evaluate the effects, of using silane coupling agent within the procedures of repairing old composite restorations with or without sandblasting their surfaces, on the clinical performance of repaired composite restorations.

METHODS

The study involved repairing 130 Class I and II defective composite restorations. After recurrent caries removal, the repair process included etching with 37 % phosphoric acid, Adper Single Bond 2 application for bonding and Filtek Z250 composite for restoring all defects. The restoration surfaces were subjected to one of the following additional surface treatments within the repair process: Control: No additional treatment; the Silane-Adhesive treatment: A separate step involved the application of a silane coupling agent after acid etching; and the Sandblast-Silane-Adhesive treatment: included intra-oral sandblasting of old composite surfaces followed by silane application. Two calibrated examiners evaluated all repaired restorations according to a modified USPHS criteria after 6 months. Comparisons of the clinical performance between the treatment groups were made using Chi-square test, while responses to cold tests before and after repair treatment were made using Wilcoxon's Signed Rank's (α = 0.05).

RESULTS

Of 130 cases, only 116 cases turned up for evaluation. The primary reasons for composite repair were recurrent caries and anatomical deficiencies. No statistically significant differences were found between the groups for all clinical criteria (p > 0.05). The control group experienced one total and two partial retention losses.

CONCLUSIONS

The application of a silane coupling agent, with or without intra-oral sandblasting, demonstrated no improvement on the clinical performance of repaired posterior composites after 6-months.

CLINICAL SIGNIFICANCE

Surface treatment of defective composite restorations using silane with intra-oral sandblasting within their repair process offered marginal improvement in their clinical performance over conventional etching technique, but insignificantly so. Repair reduced exaggerated cold test responses and eliminated POS within 6-months. Repair reduces cold sensitivity and promotes restoration longevity. This clinical trial was registered at ClinicalTrials.gov with the registration number NCT06005571.

Dental amalgam teaching phase-out - a step too soon? Foundation trainees' experience of amalgam use in dental school compared to practice: a mixed-methods survey

Aim This study aimed to explore disparities in experience of UK dental foundation trainees in amalgam use at dental school compared to their first year in dental practice.Methods A modified version of the 'survey of Yorkshire dentists' targeted the dental foundation trainees. A mixed-method of quantitative and thematic content analysis was undertaken for the close-ended and free-text responses, respectively.Results Only 35% of participants described their confidence level as 'satisfactory' in placing dental amalgam before starting their dental foundation training and 51% scored the level of teaching between 'very poor' and 'satisfactory'. In total, 63% of respondents were in favour of receiving additional support in placing amalgam restorations during their undergraduate training. Participants indicated that the consequences of amalgam phase-out are increased appointment times and decreased quality of care due to patient and health service unaffordability of amalgam alternatives.Conclusion These findings raise concerns regarding newly qualified undergraduates' confidence, experience and skill in placing amalgams. This suggests the need to increase undergraduate education and training to improve undergraduates' skills and confidence in amalgam procedures to reduce the gap between the dental schools and real-world practice.

Teaching of posterior composites for the restoration of permanent teeth in undergraduate dental training programmes: Systematic review and meta-analysis

OBJECTIVES

To systematically assess aspects of teaching of posterior composite restorations (PCRs) in permanent teeth in dental schools.

STUDY SELECTION

Quantitative studies reporting on dental schools' teaching regarding the placement of PCRs in permanent teeth. Random-effects meta-analyses and meta-regressions were performed. Risk of bias was assessed based on the Medical Education Research Study Quality Instrument (MERSQI).

SOURCES

Electronic databases (MEDLINE via PubMed, EMBASE via Ovid, Web of Science, and Scopus) were searched in January 2023.

DATA

Forty sources reporting on 34 studies having surveyed 1,286 dental schools were included. Overall, 92.7% (95%-CI: 88.2-95.5) of dental schools reported to teach PCRs. PCRs in three-surface Class II cavities are taught by 82.0% (95%-CI: 70.4-89.7). The mandatory use of liners in deep cavities is taught by 78.3% (95%-CI: 68.9-85.5), and 44.0% (95%-CI: 34.3-54.2) reported to teach bulk-fill composites. While most posterior restorations placed by students were composites (56.1%; 95%-CI: 46.0-65.8), 94.7% (95%-CI: 86.6-98.0) of dental schools (still) teach posterior amalgam restorations. The proportion of dental schools teaching PCRs in three-surface Class II cavities increased and the mean proportion of PCRs among all posterior restorations increased over time (padj.≤0.003).

CONCLUSIONS

The teaching of PCRs in dental schools around the world reflects the increased use of resin composite in clinical practice, with students in countries where dental amalgam continues to be used, placing more posterior composites than restorations of dental amalgam. The teaching of PCRs, which is anticipated to increase, will continue to be refined with further developments in adhesive materials, devices, instrumentation, and techniques.

CLINICAL SIGNIFICANCE

Graduating dentists can be expected to be familiar with the use of resin composites for the restoration of posterior teeth.

Some Myths in Dentin Bonding: An Evidence-Based Perspective

Laboratory investigations are essential models responsible for science development. However, laboratory discoveries must be confirmed in a clinical environment where many known and unknown variables and complex mechanisms are involved. Using conclusions from laboratory studies to make clinical recommendations can lead to widespread "unreliable truths" or so-called myths in any field of knowledge. These myths may increase the costs (financial and time) or even cause harm (side effects) that would be unnecessary, given that the current protocol or conduct was previously evaluated in a more complex and complete clinical setting. This article will discuss certain myths in dentin bonding that may influence clinical decision-making, bringing some principles of evidence-based practice to allow a more critical evaluation of the literature findings.

Properties of A Model Self-Healing Microcapsule-Based Dental Composite Reinforced with Silica Nanoparticles

Aim: The purpose of this study was to evaluate the mechanical properties of an experimental self-healing dental composite model (SHDC) composed of SiO₂ nanoparticles with varying percentages of triethylene glycol dimethacrylate (TEGDMA) monomer and N,N-dihydroxyethyl-p-toluidine (DHEPT) amine microcapsules. Materials and methods: Microcapsules were prepared by in-situ polymerisation of PUF shells, as explained in our previous work. The model SHDC included bisphenol A glycidyl dimethacrylate (Bis-GMA:TEGDMA) (1:1), 1 wt% phenyl bis(2,4,6-trimethylbenzoyl) phosphine oxide (BAPO), 0.5 wt% benzoyl peroxide (BPO) catalyst, 20 wt% silanised silica dioxide (SiO₂) (15 nm) and (0, 2.5, 5, 7.5, 10 wt%) of microcapsules (120 ± 45 μm). Light transmission, hardness, degree of conversion (DC), flexural strength and elastic modulus of the SHDC model were measured. Results: The degree of conversion of the SHDC ranged from 73 to 76% 24 h after polymerisation. Hardness measurements ranged from 22 to 26 VHN (p > 0.05); however, the flexural strength was adversely affected from 80 to 55 MPa with increasing microcapsules of up to 10 wt% in the composites (p < 0.05). Conclusion: Only flexural strength decreased drastically ~30% with increasing microcapsules (>10 wt%) in the composites. All other measured properties were not significantly affected. Accordingly, we recommend a stronger composite material that could be created by increasing the filler content distribution in order to achieve a hybrid self-healing composite with enhanced mechanical properties.

Placement of Posterior Composite Restorations: A Cross-Sectional Study of Dental Practitioners in Al-Kharj, Saudi Arabia

Dental practitioner-related factors can affect the quality of composite restorations. This study aimed to investigate the clinical techniques used by dental practitioners (DPs) while placing direct posterior composite restorations. Methods: A questionnaire survey that sought information related to the placement of posterior composite restorations was delivered to 161 DPs working in the Al-Kharj area, Saudi Arabia. The collected data were statistically analyzed using Pearson’s Chi-square test and Fisher’s exact test considering the DP’s working sector and the answered questions. Results: A total of 123 DPs completed the survey (76.4% response rate). There was a statistically significant difference between DPs working in the private sector and those working in the governmental sector in 7 out of 17 questionnaire items namely: preparing a minimum depth of 2 mm, (p = 0.001); mechanical means of retention, (p = 0.003); operative field isolation, (p = 0.004); adhesive strategy, (p < 0.001); light-curing unit used, (p = 0.013); the use of radiometer, (p = 0.023), and dental matrix selection, (p < 0.001). Conclusion: The clinical techniques applied by DPs working in the private sector in Al-Kharj, Saudi Arabia when placing posterior composite restorations, including the specifications of cavity preparation, operative field isolation, and selection of the dental matrix system, may be substandard compared to those applied by DPs working in the governmental sector.

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.

A Contemporary Evaluation on Posterior Direct Restoration Teaching among Undergraduates in Dental Schools in Malaysia

There is a current trend to restore posterior teeth with composite resin due to increasing demands on natural tooth colour restoration and increased concern about the safety of amalgam restorations. The objective was to evaluate the current teaching of posterior direct restoration among restorative dental lecturers in Malaysia compared to available international literature. An online questionnaire, which sought information on the teaching of posterior restoration was developed and distributed to 13 dental schools in Malaysia. The response rate for the questionnaire was 53.8%. The most popular posterior restoration teaching methods among the respondents were lecture (95.7%), demonstration (87.0%) and problem-based learning (PBL) (73.9%), while continuous assessment and a practical competency test (82.6%) were the most popular assessment methods. Placing a hard setting calcium hydroxide and GIC base for deep cavity restored by composite restoration was taught in 79.2% of cases. The standard protocols for posterior composite restoration were incremental filling in deep cavity (87.5%), using circumferential metal bands with wooden wedge (91.7%), with a total etch system (95.8%), using a light emitting diode (LED) light curing unit (91.7%), finishing using water cooling (80%) and finishing with a disc (87.5%). Graduates from dental schools in Malaysia received similar theoretical, preclinical and clinical teaching on posterior restoration techniques, although there were variations in the delivery methods, techniques and assessments, pointing to a need for uniformity and consensus.

Choice of Restorative Materials for Direct Posterior Restorations among Undergraduate Saudi College Students

Background:

The most common restorative materials used in dentistry are amalgam and composite. Amalgam is a controversial material owing to its mercury toxicity. With recent advances in the properties of composite materials, there has been a shift towards its use.

Objectives:

The aim of this study was to understand the perceptions of undergraduate dental students in a northern Saudi Arabian dental school about the choice of restorative materials for restoring posterior teeth.

Methodology:

The study included undergraduate students studying in 4th and 5th year dental program in College of Dentistry, Jouf University. A four-item questionnaire with 18 close-ended questions was developed by the investigators, which were hand delivered to all the students. Data analysis is presented through tables and descriptive methods.

Results:

A total of 98 (out of 131) undergraduate students participated in this study. Overall, the students reported a significantly strong influence of the type of restorative materials in relation to the cavity size and margin of the restorations along with the esthetics factor(p<0.05). There was slight influence on the student’s choice because of the instructor's influence, whereas the students felt they were knowledgeable and had appropriate training to use either amalgam or composite. The study also found that patient’s preference had a strong influence on choosing composite material. The students were mostly not influenced while choosing the material as far as the safety of it was concerned. However, the patient’s influence was slight when it came to the choice of the material. A significant difference was noted among the students when it came to pregnancy-related safety concerns where the choice of material was not influenced by either amalgam or composite (p=.002).

Conclusion:

The undergraduate dental students at College of Dentistry, Jouf University are comfortable in using both amalgam and composite as a posterior restorative material. They are knowledgeable about both the materials and are adequately trained to use either one.

Dental Applications of Carbon Nanotubes

Glass ionomer cements and resin-based composites are promising materials in restorative dentistry. However, their limited mechanical properties and the risk of bulk/marginal fracture compromise their lifespan. Intensive research has been conducted to understand and develop new materials that can mimic the functional behavior of the oral cavity. Nanotechnological approaches have emerged to treat oral infections and become a part of scaffolds for tissue regeneration. Carbon nanotubes are promising materials to create multifunctional platforms for dental applications. This review provides a comprehensive survey of and information on the status of this state-of-the-art technology and describes the development of glass ionomers reinforced with carbon nanotubes possessing improved mechanical properties. The applications of carbon nanotubes in drug delivery and tissue engineering for healing infections and lesions of the oral cavity are also described. The review concludes with a summary of the current status and presents a vision of future applications of carbon nanotubes in the practice of dentistry.

Current and future trends in the teaching of direct posterior resin composites in Malaysian dental schools: a cross-sectional study

OBJECTIVE

To investigate the current and future teaching of posterior composite restorations in undergraduate curricula in Malaysian dental schools.

METHODS

A 24-item validated questionnaire including closed and open questions on the teaching of posterior composites was emailed to faculty members in all 13 Dental Schools in Malaysia. Responses were compiled on Excel and analysed.

RESULTS

All 13 dental schools responded to the survey yielding a 100 % response. All schools indicated the use of posterior composites for 2- and 3-surface cavities in premolars and molars. The didactic teaching time devoted to composites was greater than for amalgam (38 h vs 29 h). Clinically, most posterior restorations placed by students were composites (average 74.1 %, range 10 %-100 %); the remaining 25.9 % were amalgams (range, 0 %-50 %). Slot-type cavities were the preparation techniques most commonly taught (n = 11,84.6 %). The use of rubber dam for moisture control was mandatory in most schools (n = 11, 84.6 %). History of adverse reaction to composites was found to be the most common contraindication to composite placement. The phase down of teaching and use of amalgam in Malaysia is expected to occur within the next six years.

CONCLUSION

The trend to increase the teaching of posterior composites reported for other countries is confirmed by the findings from Malaysian dental schools. Notwithstanding this trend, the use of amalgam is still taught, and future studies are required to investigate the implications of the phase down of amalgam in favour of posterior composites.

CLINICAL SIGNIFICANCE

Notwithstanding the increase in the teaching of posterior composites there is a pressing need to update and refine clinical guidelines for the teaching of posterior composites globally.

A retrospective clinical study on the survival of posterior composite restorations in a primary care dental outreach setting over 11years

OBJECTIVES

To investigate the survival in terms of time to re-intervention of composite restorations in posterior teeth among patients attending for treatment at a primary care dental outreach setting over an 11-year period and to determine whether dental, patient or operator factors influenced this.

METHODS

Electronic primary dental care data were collected on individual patients, including information on their dental treatment and socio-demographics as well as service provision, key performance indicators and student activity.

RESULTS

A total of 1086 patients had at least one posterior composite placed between 2007 and 2018. This amounted to 3194 restorations placed of which 308 had a re-intervention within the 11-year period. For all restorations, the annual failure rate at 1 year was 5.73 %, at 5 years was 16.78 % and at 10 years was 18.74 %. A logistic regression showed that when compared to the least deprived 5^th quintile, the most deprived 1^st and 2^nd quintiles were significantly less likely to have a re-intervention, being 49.2 % (p = 0.022) and 53.2 % (p = 0.031) less likely, respectively.

CONCLUSIONS

The survival rates of posterior composite restorations placed at a single outreach centre providing undergraduate dental training in the South of England, mirrors other studies. The new findings presented suggest similar re-intervention rates between dental students and dental hygiene-therapy students. This study's findings around patient deprivation and rate and time of re-intervention raises important questions related to the need for targeted dental and after care for certain groups in the population.

CLINICAL SIGNIFICANCE

Understanding the factors associated with re-intervention of restorations provided to patients has an impact on patients and dental practices. Also, as we consider widening use of skill mix in dentistry to increase access to care, parity in provision of treatments within the dental team increases opportunities for delegation of tasks.

Fall of amalgam restoration: a 10-year analysis of an Australian university dental clinic

BACKGROUND

The use of amalgam in Dentistry has decreased since the 1980s. This study aimed to (i) assess the time trend in the usage of amalgam and composite in posterior teeth at Griffith University Dental Clinic from 2010 to 2019; (ii) to test whether this trend varied according to the dental health provider.

METHODS

We analysed clinic records from 2010 to 2019. Prais-Winsten analyses were performed, and the average annual percentages change (AAPC) for amalgam and composite was estimated.

RESULTS

There were 397,013 procedures, including 80,995 direct posterior restorations. Amalgam use decreased from 12.9% in 2010 to 0.5% in 2019 among students, while composite use increased from 87.1% to 99.5% of posterior restorations. The annual increase of the composite was 1.4% per year for students, while amalgam decreased by 30.2% per year on average. A similar trend was noted among the dentists.

CONCLUSIONS

A significant decrease in the use of amalgam was observed over time for both students and professionals. This trend raises questions about curriculum reviews, focusing on the repair, maintenance and safe removal of amalgam while reinforcing the learning on Minimally Invasive Dentistry and composite restorations based on the patient's caries risk.

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.

Awareness about dental amalgam among Turkish dentists and patients: a questionnaire and search engine based cross-sectional study

OBJECTIVES

There has been considerable controversy concerning the health risks and benefits of using mercury-containing amalgam. This study aimed to evaluate the Turkish dentists' and patients' preference and opinion about amalgam and to assess Internet search trends about amalgam.

METHODS

The study consists of three stages. The first two stages of the study are cross-sectional studies to verify both the patients' perception with amalgam restorations and dentists' attitudes regarding the use of dental amalgam. The third stage of the study evaluated the Internet search trends of Turkish people about mercury and amalgam related concerns between 2004 and 2018.

RESULTS

A total of 320 patients (180 female, 140 male) and 1,211 dentists (533 female, 678 male) participated in this study. Majority of the patients have no idea about the type of dental restorations and effect of dental materials on their health. 188 (58.8%) participants stated that they would not prefer amalgam restoration in their teeth as amalgam is unaesthetic. A total of 24% (291) of the dentists used amalgam routinely; 9.5% (156) of them used amalgam rarely, and 63.1% (764) did not use amalgam at all. The reason for not using amalgam included the patients' desire and unaesthetic properties. According to the Internet search trends, Turkish people do not know as much about amalgam as people in the rest of the world.

CONCLUSION

Awareness about dental amalgam is low among patients studied. Although dentists do not use dental amalgam frequently, they disagree on banning dental amalgam.

Amalgam phase down: baseline data preceding implementation in Nigeria

OBJECTIVE

The Minimata Convention on mercury includes amalgam phase-down and eventual phase-out from dentistry. To aid its subsequent evaluation it is important to have baseline data of amalgam use in a locality prior to implementing a phase-down.

METHODOLOGY

Records of patients spanning 5 years from January 2011 to January 2016 were analysed to determine and the compare frequency of amalgam usage with other dental materials for carious teeth restorations in a Nigerian university teaching hospital. Classes of cavities restored and cadres of operators who employed the different materials were included. Institutional ethics committee approval was obtained prior to commencing the study.

RESULTS

2,058 patients' records were retrieved, 59% females and 41% males. Their ages ranged 19-80 years, mean 33.5 ± 12.7 years, young adults 20-39 years old were the majority (62.9%). Filling materials included 57.5% amalgam, 17.6% glass ionomer cement (GIC) and 24.9% resin composite. Class I restorations constituted 70.5% of amalgam restorations, while Class II restorations made up 29.4% and Class V restorations accounted for 0.1%. Undergraduate dental students placed most of the amalgam restorations (60.5%), and 78.9% of all their restorations were amalgam. Less experienced dentists used all materials equally; the more experienced dentists placed more composite resin and GIC (43.3%).

CONCLUSION

Amalgam fillings constituted nearly 60% of the restorations of carious teeth. Training of dental students in placement of non-mercury alternatives to amalgam and Minimum Intervention Dentistry needs to be emphasized in dental schools. Phase-down of amalgam should be intensified in Nigeria with the ultimate aim of a phase-out in line with the Minamata Convention.

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.

Novel antibacterial calcium phosphate nanocomposite with long-term ion recharge and re-release to inhibit caries

Short-term studies on calcium-phosphate (CaP) ion-rechargeable composites were reported. The long-term rechargeability is important but unknown. The objectives of this study were to investigate nanocomposite with strong antibacterial and ion-recharge capabilities containing dimethylaminododecyl methacrylate (DMAHDM) and nanoparticles of amorphous calcium phosphate (NACP), and evaluate long-term ion-recharge by testing for 12 cycles (taking 6 months to complete) for the first time. Three groups were tested: (1) Heliomolar control; (2) Resin+20%NACP+50%glass; (3) Resin+3%DMAHDM+20%NACP+50%glass. Biofilm acid and colony-forming units (CFU) were measured. Ion-recharge was tested for 12 cycles. NACP-DMAHDM composite reduced biofilm acid, and reduced CFU by 4 logs. High levels of ion releases were maintained throughout 12 cycles of recharge, maintaining steady-state releases without reduction in 6 months (p>0.1), representing long-term remineralization potential. Bioactive nanocomposite demonstrated long-term ion-rechargeability for the first time, showed remineralization and potent anti-biofilm functions, with promise for tooth restorations to combat caries.

Next generation of dentists moving to amalgam-free dentistry: Survey of posterior restorations teaching in North America

OBJECTIVES

The dental field is gradually reducing the use of amalgam and moving towards adhesive restoration. This change is in accordance with the advancement and improvement of composite resin materials and adhesion systems. Consequently, posterior cavity preparations teaching should be re-examined to determine whether dental schools are adapting their curriculum to fit the current trends in dentistry and what rationale supports their decisions.

METHODS

An online questionnaire was constructed to assess the time dedicated to teaching composite materials and amalgam, in addition to the principles of posterior preparations, for composite restorations in North American dental schools.

RESULTS

A total 33 schools responded to the questionnaire. A large variation was found in teaching methods and techniques of posterior restorations. The reasoning for teaching amalgam restorations was diverse as were the principles of composite resin preparation taught.

CONCLUSION

No agreed principles of cavity preparation for resin composite restorations were found, as opposed to explicit agreement on amalgam cavity preparations. The results demonstrate a lack of clear guidelines for cavity preparation of resin composite restorations. Dental schools may benefit when a consensus on this topic is achieved.

A randomised controlled study on the effects of different surface treatments and adhesive self-etch functional monomers on the immediate repair bond strength and integrity of the repaired resin composite interface

OBJECTIVES

To evaluate the effects of different surface conditioning methods on the immediate repair bond strength and integrity of the repaired composite interface.

METHODS

One hundred and five resin composite blocks made of a nanohybrid resin composite were randomly assigned to one of the following surface conditioning groups (n = 15/group): Group 1: Gluma Self Etch™ adhesive system, Group 2: Tokuyama Bond Force II™ adhesive system, Group 3: non-roughened and non-conditioned surfaces, Group 4: sandblasting and Gluma Self Etch™, Group 5: sandblasting and Tokuyama Bond Force II™, Group 6: sandblasting only. A positive control group was also used. Resin composite identical to the substrate was applied and the repaired specimens were subjected to shear bond strength (SBS) testing. Representative samples from all groups were subjected to scanning electron microscopy and surface profilometry to determine their mode of failure. The data were analysed statistically using Analysis of Variance (ANOVA) and two independent sample t-test (α = 0.05).

RESULTS

The mean SBS of all test groups ranged between 1.92 and 5.40 MPa and varied with the degree of composite surface roughness and the type of adhesive system employed. Significantly highest SBS values (5.40 ± 0.36 MPa) were obtained in Group 5 (p = 0.017) which were comparable to the coherent strength of the resin composite in the positive control group (p > 0.05).

CONCLUSIONS

Under the tested conditions, significantly greater SBS of repaired resin composite was achieved when the substrate surface was conditioned by sandblasting followed by the application of the Tokuyama Bond Force II™ adhesive system.

CLINICAL SIGNIFICANCE

Effecting a repair of a nanohybrid composite restoration with sandblasting and the application of TBF II would seem to enhance the interfacial bond strength and integrity of the repaired resin composite interface. Clinical trials are necessary to determine the usefulness of this technique.

Poly(amido amine) and rechargeable adhesive containing calcium phosphate nanoparticles for long-term dentin remineralization

OBJECTIVES

The objective of the present study was to investigate long-term dentin remineralization via the combination of poly(amido amine) (PAMAM) with a novel rechargeable adhesive containing nanoparticles of amorphous calcium phosphate (NACP).

METHODS

The NACP adhesive was immersed in lactic acid at pH 4 to exhaust its calcium (Ca) and phosphate (P) ion release, and then recharged with Ca and P ions. Dentin samples were pre-demineralized with 37% phosphoric acid, and then divided into four groups: (1) dentin control, (2) dentin treated with PAMAM, (3) dentin with recharged NACP adhesive, (4) dentin with PAMAM + recharged NACP adhesive. In group (2) and (4), the PAMAM-coated dentin was immersed in phosphate-buffered saline with vigorous shaking for 77 days to accelerate any detachment of the PAMAM macromolecules from the demineralized dentin. Samples were treated with a cyclic remineralization/demineralization regimen for 21 days.

RESULTS

After 77 days of fluid flow challenge, the immersed PAMAM still retained its nucleation template function. The recharged NACP adhesive possessed sustained ion re-release and acid-neutralization capability, both of which did not decrease with repeated recharge and re-release cycles. The immersed PAMAM with the recharged NACP adhesive achieved long-term dentin remineralization, and restored dentin hardness to that of healthy dentin.

CONCLUSIONS

The PAMAM + NACP adhesive completely remineralizes pre-demineralized dentin even after long-term fluid challenges and provides long-term remineralization to protect tooth structures.

CLINICAL SIGNIFICANCE

The novel PAMAM + NACP adhesive provides long-term bond protection and caries inhibition to increase the longevity of resin-based restorations.

Effect of interface surface design on the fracture behavior of bilayered composites

This study aimed to evaluate the effect of different interface designs on the load‐bearing capacity of bilayered composite structures (BLS). Cylindrical specimens of BLS were prepared from base composite of 3.5 mm thickness and surface composite of 1.5 mm thickness (n = 80). Two different base composites – flowable bulk‐fill (FBF) [smart dentin replacement (SDR)] and short fiber‐reinforced (FRC) (everX Posterior) – were evaluated, and conventional composite (G‐ænial Posterior) was used as the surface layer. Four different interface designs were used: (i) pyramidal; (ii) mesh; (iii) linear grooves; and (iv) flat surface (control). Three‐dimensional printed molds were fabricated to standardize the interface design between the surface and the base composites. The specimens were then statically loaded with a steel ball until fracture using a universal testing machine. Fracture types were classified into catastrophic, complete, and partial bulk. anova revealed that both the material and the interface design had a statistically significant effect on the load‐bearing capacity. Flowable bulk‐fill showed lower mean load‐bearing capacity than FRC in all the interface designs tested, except for the flat surface design. Fracture analysis showed that FRC demonstrated up to 100% partial bulk fractures with the pyramid interface design, but no incidence of catastrophic bulk fracture. By contrast, FBF demonstrated up to 84.6% and 40% catastrophic bulk fractures with the flat interface design but no incidence of partial bulk fracture. Consequently, the interface designs studied enhanced the fracture behavior of BLS.

Novel multifunctional nanocomposite for root caries restorations to inhibit periodontitis-related pathogens

OBJECTIVES

The objectives of this study were to: (1) develop a novel multifunctional composite with nanoparticles of silver (NAg), 2-methacryloyloxyethyl phosphorylcholine (MPC), dimethylaminohexadecyl methacrylate (DMAHDM) and nanoparticles of amorphous calcium phosphate (NACP); and (2) investigate biofilm-inhibition via the multifunctional nanocomposite against three species of periodontal pathogens for the first time.

METHODS

The multifunctional nanocomposite was fabricated by incorporating NAg, MPC, DMAHDM and NACP into the resin consisting of pyromellitic glycerol dimethacrylate (PMDGDM) and ethoxylated bisphenol A dimethacrylate (EBPADMA). Three species (Porphyromonas gingivalis, Aggregatibacter actinomycetemcomitans and Fusobacterium nucleatum) were tested for metabolic activity (MTT), live/dead staining, polysaccharide production and colony-forming units (CFU) of biofilms grown on resins.

RESULTS

Incorporation of 0.08% to 0.12% NAg, 3% MPC, 3% DMAHDM and 30% NACP did not compromise the mechanical properties of the composite (p > 0.1). The multifunctional nanocomposite reduced protein adsorption to nearly 1/10 of that of a commercial control (p < 0.05). For all three species, the biofilm CFU was reduced by about 5 and 1 orders of magnitude via the nanocomposite containing NAg + MPC + DMAHDM, compared to commercial control and the composite with MPC + DMAHDM, respectively.

CONCLUSIONS

The novel multifunctional nanocomposite achieved the greatest reduction in metabolic activity, polysaccharide and biofilm growth of three periodontal pathogens.

CLINICAL SIGNIFICANCE

The strongly-antibacterial, multifunctional composite is promising for treating root lesions, alleviating periodontitis and protecting the periodontal tissues.

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.

Reparative Dentistry: Possibilities and Limitations

Purpose of Review

Defective dental restorations are amongst the most common encounters in general dental practice. Replacement of defective restorations is often costly and commonly results in the sacrifice of sound tooth structure, thereby compromising the vitality of the dental pulp, potentially resulting in the acceleration of the restoration cycle and premature loss of the restored tooth. With advances in adhesive dentistry, ‘reparative dentistry’ is becoming an important area of minimally invasive dentistry. This article highlights the detrimental biological effects of restoration replacement and provides an overview of current knowledge and understanding of restoration repair as a safe and effective alternative approach to replacement.

Recent Findings

The literature reviewed showed that a growing body of evidence from clinical studies indicates that repaired restorations have similar survival outcomes in patients with low and medium caries risk compared to replaced restorations and are clinically acceptable over a 12-year follow-up of clinical service. Teeth with repaired restorations are less likely to require aggressive interventions such as endodontic treatment or extraction compared to those with replaced restorations.

Summary

Repair options should be carried out wherever possible as minimally interventional procedures in order to increase the longevity of the remaining part of the restoration and the restored tooth unit. Restoration replacement should be considered as the last resort when there are no other viable alternatives.

Bulk-fill resin-based composite restorative materials: a review

Resin-based composite (RBC) materials are increasingly being used for the restoration of posterior teeth. The increasing demand for aesthetic, tooth-coloured restorations coupled with the patient's concerns regarding the use of mercury containing restorations, has driven a surge in the use of RBC materials. With the Minamata Convention in 2013 calling for the phase-out of dental amalgam and dental schools increasingly teaching techniques for RBC restorations in posterior teeth, it is likely that the dental profession's reliance upon RBC for the restoration of posterior teeth will only increase. In order to simplify and speed-up the placement of large posterior RBCs, manufacturers have produced a range of materials which can be placed in single or deeper increments, known as bulk-fill RBCs. Over a relatively short period of time many bulk-fill RBCs have been marketed quoting increment depths between 4-10 mm. The placement of these larger increments of RBC may reduce the time needed when placing posterior restorations and thereby reduce technique sensitivity. This article aims to review the properties and handling characteristics of the bulk-fill RBC materials currently available, while advising the optimal techniques of placement.

Novel rechargeable calcium phosphate nanocomposite with antibacterial activity to suppress biofilm acids and dental caries

OBJECTIVE

Rechargeable calcium phosphate (CaP) composites were developed recently. However, none of the rechargeable CaP composites was antibacterial. The objectives of this study were to develop the first rechargeable CaP composite that was antibacterial, and to investigate the effects of adding dimethylaminohexadecyl methacrylate (DMAHDM) into rechargeable CaP composite on ion rechargeability and re-release as well as biofilm properties.

METHODS

DMAHDM was synthesized via a Menschutkin reaction. Nanoparticles of amorphous calcium phosphate (NACP) were synthesized using a spray-drying technique. The resin contained ethoxylated bisphenol A dimethacrylate (EBPADMA) and pyromellitic glycerol dimethacrylate (PMGDM). Two composites were fabricated: rechargeable NACP composite, and rechargeable NACP-DMAHDM composite. Mechanical properties and ion release and recharge were measured. A dental plaque microcosm biofilm model using saliva was tested.

RESULTS

Flexural strength and elastic modulus of rechargeable NACP and NACP-DMAHDM composites matched commercial control composite (p > 0.1). NACP-DMAHDM inhibited biofilm metabolic activity and lactic acid, and reduced biofilm colony-forming units (CFU) by 3-4 log. NACP and NACP-DMAHDM showed similar Ca and P ion recharge and re-release (p > 0.1). Therefore, adding DMAHDM did not compromise the ion rechargeability. One recharge yielded continuous release for 42 d. The release was maintained at the same level with increasing number of recharge cycles, indicating long-term ion release and remineralization capability.

CONCLUSIONS

The first CaP rechargeable and antibacterial composite was developed. Adding DMAHDM into the rechargeable NACP composite did not adversely affect the Ca and P ion release and recharge, and the composite had much less biofilm growth and lactic acid production, with CFU reduction by 3-4 log.

CLINICAL SIGNIFICANCE

This novel CaP rechargeable composite with long-term remineralization and antibacterial properties is promising for tooth restorations to inhibit caries.

An end to linings under posterior composites?

BACKGROUND AND OVERVIEW

There is an uncertainty among dentists as to whether to place a lining under a direct posterior composite restoration and, if so, what material or combination of materials to use. In this article, the authors consider the evidence for the placement of a lining under posterior composites of different depths, including indications and contraindications for different lining materials.

CONCLUSIONS

The available evidence does not support the use of linings under direct, bonded posterior composites, unless being placed in deep cavities for therapeutic reasons.

PRACTICAL IMPLICATIONS

The best available evidence indicates that dentists can place posterior composites without linings, except for therapeutic purposes, with no adverse effect on postoperative complications, with possible improvements in performance in clinical service, and with efficiency savings in chairside time.

Novel dental adhesive with triple benefits of calcium phosphate recharge, protein-repellent and antibacterial functions

OBJECTIVE

A new adhesive containing nanoparticles of amorphous calcium phosphate (NACP) with calcium (Ca) and phosphate (P) ion rechargeability was recently developed; however, it was not antibacterial. The objectives of this study were to: (1) develop a novel adhesive with triple benefits of Ca and P ion recharge, protein-repellent and antibacterial functions via dimethylaminohexadecyl methacrylate (DMAHDM) and 2-methacryloyloxyethyl phosphorylcholine (MPC); and (2) investigate dentin bond strength, protein adsorption, Ca and P ion concentration, microcosm biofilm response and pH properties.

METHODS

MPC, DMAHDM and NACP were mixed into a resin consisting of ethoxylated bisphenol A dimethacrylate (EBPADMA), pyromellitic glycerol dimethacrylate (PMGDM), 2-hydroxyethyl methacrylate (HEMA) and bisphenol A glycidyl dimethacrylate (BisGMA). Protein adsorption was measured using a micro bicinchoninic acid method. A human saliva microcosm biofilm model was tested on resins. Colony-forming units (CFU), live/dead assay, metabolic activity, Ca and P ion concentration and biofilm culture medium pH were determined.

RESULTS

The adhesive with 5% MPC+5% DMAHDM+30% NACP inhibited biofilm growth, reducing biofilm CFU by 4 log, compared to control (p<0.05). Dentin shear bond strengths were similar (p>0.1). Biofilm medium became a Ca and P ion reservoir having ion concentration increasing with NACP filler level. The adhesive with 5% MPC+5% DMAHDM+30% NACP maintained a safe pH>6, while commercial adhesive had a cariogenic pH of 4.

SIGNIFICANCE

The new adhesive with triple benefits of Ca and P ion recharge, protein-repellent and antibacterial functions substantially reduced biofilm growth, reducing biofilm CFU by 4 orders of magnitude, and yielding a much higher pH than commercial adhesive. This novel adhesive is promising to protect tooth structures from biofilm acids. The method of using NACP, MPC and DMAHDM is promising for application to other dental materials to combat caries.

Effects of Long-Term Water-Aging on Novel Anti-Biofilm and Protein-Repellent Dental Composite

The aims of this study were to: (1) synthesize an anti-biofilm and protein-repellent dental composite by combining 2-methacryloyloxyethyl phosphorylcholine (MPC) with quaternary ammonium dimethylaminohexadecyl methacrylate (DMAHDM); and (2) evaluate the effects of water-aging for 180 days on protein resistance, bacteria-killing ability, and mechanical properties of MPC-DMAHDM composite. MPC and DMAHDM were added into a resin composite. Specimens were stored in distilled water at 37 °C for 1, 30, 90, and 180 days. Mechanical properties were measured in three-point flexure. Protein attachment onto the composite was evaluated by a micro bicinchoninic acid approach. An oral plaque microcosm biofilm model was employed to evaluate oral biofilm viability vs. water-aging time. Mechanical properties of the MPC-DMAHDM composite after 180-day immersion matched those of the commercial control composite. The composite with 3% MPC + 1.5% DMAHDM had much stronger resistance to protein adhesion than control (p < 0.05). MPC + DMAHDM achieved much stronger biofilm-eradicating effects than MPC or DMAHDM alone (p < 0.05). Biofilm colony-forming units on the 3% MPC + 1.5% DMAHDM composite were three orders of magnitude lower than commercial control. The protein-repellent and antibacterial effects were durable and showed no loss in water-aging from 1 to 180 days. The novel MPC-DMAHDM composite possessed strong and durable resistance to protein adhesion and potent bacteria-eradicating function, while matching the load-bearing ability of a commercial dental composite. The novel MPC-DMAHDM composite represents a promising means of suppressing oral plaque growth, acid production, and secondary caries.

Phase down of amalgam. Awareness of Minamata convention among Jordanian dentists

OBJECTIVES

To assess the knowledge of Jordanian dentists toward phase down of dental amalgam as recommended by the Minamata Convention, and their training and competency in placing posterior composites.  Methods: This study was conducted through structured questionnaire interviews with randomly selected cohort of dentists in Jordan between March 2015 and June 2015. Out of 230 dentists who were invited, 196 (85.2%) agreed to participate. Dentists were asked if they know about the Minamata Convention. They were also asked about their training in placement of posterior composite.  Results: Out of the 196 interviewed, only 13.8% know about Minamata Convention and 17% had an undergraduate training in favor of placing composites in posterior teeth. Approximately 50% of those dentists were not trained in using rubber dam when placing posterior composites, while only 38.3% had training in sectional matrix placement. Undergraduate training did not influence (p=0.00) the dentists' decision to remove old amalgam based on patient's demands. Only 28.1% were of the opinion of discontinuing the use of amalgam due to its alleged health and environmental hazards. There was no general agreement on the type of composite, liner, and bonding strategy when placing posterior composites. Conclusion: Dentists are not well informed on the Minamata Convention and the phase down of amalgam. Training in posterior composite placement should be given more room in undergraduate curriculum and continuous dental education.

Three-dimensional biofilm properties on dental bonding agent with varying quaternary ammonium charge densities

OBJECTIVES

Tooth-restoration interfaces are the weak link with secondary caries causing restoration failure. The objectives of this study were to develop an antimicrobial bonding agent with dimethylaminododecyl methacrylate (DMAHDM), and investigate the effects of quaternary amine charge density on three-dimensional (3D) biofilms on dental resin for the first time.

METHODS

DMAHDM was synthesized and incorporated into Scotchbond Multi-Purpose bonding agent at mass fractions of 0% (control), 2.5%, 5%, 7.5% and 10%. Streptococcus mutans bacteria were inoculated on the polymerized resin and cultured for two days to form biofilms. Confocal laser scanning microscopy was used to measure biofilm thickness, live and dead biofilm volumes, and live bacteria percentage in 3D biofilm vs. distance from resin surface.

RESULTS

Charge density of the resin had a significant effect on the antibacterial efficacy (p<0.05). Biofilms on control resin had the greatest thicknesses. Biofilm thickness and live biofilm volume decreased with increasing surface charge density (p<0.05). There were significant variations in bacterial viability along the 3D biofilm thickness (p<0.05). At 2.5% and 5% DMAHDM, the bacterial inhibition was the greatest on or near the resin surface, and the killing effect decreased away from the resin surface. At 10% DMAHDM, the entire 3D biofilm was dead and the percentage of live bacteria was nearly 0% throughout the biofilm thickness.

CONCLUSIONS

Adding new antibacterial monomer DMAHDM into dental bonding agent yielded a strong antimicrobial activity, substantially decreasing the 3D biofilm thickness, live biofilm volume, and percentage of live bacteria on cross-sections through the biofilm thickness.

SIGNIFICANCE

Novel DMAHDM-containing bonding agent with capability of inhibiting 3D biofilms is promising for a wide range of dental restorative and preventive applications to inhibit biofilms at the tooth-restoration margins and prevent secondary caries.