[Root canal post for build-up restorations: necessary or redundant?] / Wortelstift bij funderingsrestauraties: noodzakelijk of overbodig?

The purpose of root canal posts is to obtain additional retention for build-up restorations of endodontically treated teeth so they can be functionally reconstructed. Due to developments in adhesive dentistry and a lack of clinical evidence, root canal posts are used less and less. Currently, the advice of the European Society of Endodontology is to use a root canal post only in front teeth and premolars in the absence of remaining coronal dentine walls. It is important to avoid additional preparation when placing a root canal post, because this causes (additional) weakness of the tooth. The loss of dental tissue due to preparation cannot be compensated for by placing a post.

[Instruction in dental radiology]. / Scholing in de tandheelkundige radiologie.

The diagnostic use of oral radiology is an essential part of daily dental practice. Due to the potentially harmful nature of ionising radiation, the clinical use of oral radiology in the Netherlands is framed by clinical practice guidelines and regulatory requirements. Undergraduate students receive intensive theoretical and practical training in practical and theoretical radiology, with the aim of obtaining the 'Eindtermen Stralingshygiëne voor Tandartsen en Orthodontisten'-certificate, which is required for legal permission to use oral radiology in dental practice. It is recommended that the curriculum be expanded to include the areas of knowledge required to qualify for the 'Eindtermen Stralingshygiëne voor het gebruik van CBCT-toestellen door tandartsen' (the certificate for the use of conebeam radiology by dentists). The general dental practitioner is faced with changing laws and regulations in all areas of practice. One of the most significant legal changes in the field of dental radiology was the introduction of the new radiation protection and safety rules in 2014. Moreover, a large group of dentists is also being confronted with the transition from conventional to digital images, with all its challenges and changes in everyday practice.

[Technical aspects of treatments with single- and multi-unit fixed dental prostheses]. / Tandtechnische aspecten van de vervaardiging van kronen en bruggen.

For the manufacture of single- and multi-unit fixed dental prostheses, effective communication between dentist and dental technician is required. Mutual insight concerning the (im)possibilities of available treatments and technical options is prerequisitefor this communication. The manufacture of single- and multi-unit fixed dental prostheses involves 4 phases: recording the required detailed information on the relevant teeth and the occlusal system, the technical adjustments, the technical design and the technical fabrication. These phases can be accomplished through an analogue or (semi)digital procedure. Pioneering developments are computer aided design and computer aided manufacturing (CAD/CAM), and computerised milling machines. Associated with this are 3 manufacturing methods which can be distinguished: the dental practice method, the dental laboratory method and the milling centre method. Materials applied are metal alloys and ceramics, while resins are used for provisional and transitional constructions. Due to the fact that the choice of material in the analogue procedure is limited, CAD/CAM offers more options, the digital procedure is expected to gain ground gradually. It is expected that this development will provide an impulse to higher quality.

Challenges in conducting clinical research in primary care dentistry.

The integration of dentistry into primary health care is crucial for promoting patient well-being. However, clinical studies in dentistry face challenges, including issues with study design, transparency, and relevance to primary care. Clinical trials in dentistry often focus on specific issues with strict eligibility criteria, limiting the generalizability of findings. Randomized clinical trials (RCTs) face challenges in reflecting real-world conditions and using clinically relevant outcomes. The need for more pragmatic approaches and the inclusion of clinically relevant outcomes (CROs) is discussed, such as tooth loss or implant success. Solutions proposed include well-controlled observational studies, optimized data collection tools, and the integration of artificial intelligence (AI) for predictive modelling, computer-aided diagnostics and automated diagnosis. In this position paper advocates for more efficient trials with a focus on patient-centred outcomes, as well as the adoption of pragmatic study designs reflecting real-world conditions. Collaborative research networks, increased funding, enhanced data retrieval, and open science practices are also recommended. Technology, including intraoral scanners and AI, is highlighted for improving efficiency in dental research. AI is seen as a key tool for participant recruitment, predictive modelling, and outcome evaluation. However, ethical considerations and ongoing validation are emphasized to ensure the reliability and trustworthiness of AI-driven solutions in dental research. In conclusion, the efficient conduct of clinical research in primary care dentistry requires a comprehensive approach, including changes in study design, data collection, and analytical methods. The integration of AI is seen as pivotal in achieving these objectives in a meaningful and efficient way.

[Resin-bonded fixed partial dentures]. / Adhesiefbruggen.

A resin-bonded fixed partial denture is a prosthetic construction which can replace I or several teeth in an occlusal system and which comprises a pontic element which is adhesively attached to 1 or more abutment teeth. To compensate for the limited shear strength of the adhesive layer, the Jixed partial denture is occlusally supported by the abutment(s). A direct resin-bonded fixed partial denture is made of composite, reinforced or not by a frame of flexible metal or fiber material. For an indirect resin-bonded fixed partial denture, a metal, fibre-reinforced composite or ceramic substructure is fabricated in a dental laboratory. The basic principle of a resin-bonded fixed partial denture is minimal invasiveness. However, a restoration in an abutment tooth requires a certain occlusal space which is realized by tooth preparation. Resistance preparations may be performed to improve the longevity of resin-bonded fixed partial dentures. Both financially and biologically, a resin-bonded bridge is a cost-effective prosthetic construction. The longevity is limited, but when the construction fails the negative consequences for the abutments are generally limited, which leaves open several types of other treatments.

[The conventional and the digital impression method for single-unit and multi-unit fixed dental prostheses]. / De conventionele en de digitale afdrukmethode voor kronen en bruggen.

To manufacture single-unit and multi-unit fixed dental prostheses, an accurate cast is required. Casts can be obtained either by the conventional or the digital impression method. For both methods, dry tooth surfaces and a well exposed finish line of the tooth preparation are required. The conventional impression method requires an elastic impression material. Elastomers have a high detail accuracy, which can produce, in combination with a good fitting and rigid impression tray, an impression with reliable dimensional stability. Based on the number of different impression material consistencies used and the number ofphases of the impression procedure, several options of the conventional impression method can be distinguished. For the digital impression method, teeth or implants are scanned to produce a digital cast which can be used directly with the help of computer technology to produce single-unit or multi-unit fixed dental prostheses. The digital impression method has a number of advantages when compared to the conventional impression method, but is not applicable for all prosthetic cases.

[Contact wear related to single- and multi-unit dental prostheses]. / Contactslijtage in relatie tot kronen en bruggen.

Occlusal surfaces of teeth and restorations wear by repeated antagonistic contact. Two-body wear is the result of direct contact between occlusal surfaces. In cases of three-body wear, food is found between antagonistic teeth. Contact wear is expressed predominantly by abrasion and material fatigue. Erosion is a type of wear which does not involve direct antagonistic contact. Qualitative methods exist for registering occlusal tooth wear. Wear of restorations can be measured using casts. An obvious method for comparing rates of wear of restorative materials is laboratory research. This method has demonstrated that the wear rates of composite and enamel are similar. Cast metals and in particular ceramic wear less than enamel. The relation between oral factors and the rate of tooth wear is not always clear. Wellpolished surfaces of restorations wear less quickly and have less effect on the wearing of antagonistic teeth than rougher restoration surfaces.

[Determining and recording maxillomandibular relationships for the fabrication of single-unit and multi-unit fixed dental prostheses]. / Bepaling en registratie van de maxillomandibulaire relatie bij de vervaardiging van kronen en bruggen.

In a correctly functioning occlusal system, the design of the occlusal parts of single-unit and multi-unit fixed dental prostheses is generally determined by the maximum intercuspation. Determining and recording the maxillomandibular relationships is only required in case the adjacent teeth do not offer adequate support or reference to put the maxillary and mandibular cast in maximum intercuspation or in case the existing occlusion needs a well-structured alteration. The maxillomandibular relationships can be determined and registered analogously and digitally and on that basis the maxillary and mandibular casts can be mounted in a (virtual) occludator or articulator. In the absence of a distinct occlusal plane, one may consider first carrying out a facebow recording and transfer. Usually, the accuracy of determining and recording the maxillomandibular relationships does not increase when using more complicated methods.

[Attaching single- and multi-unit fixed dental prostheses]. / Bevestiging van kronen en bruggen.

A single- or multi-unit fixed dental prosthesis can be attached to the abutment teeth through mechanical retention and gap sealing or by adhesion. For sealing the gap, water-soluble cements are appropriate, such as zinc phosphate, polycarboxylate, and (resin-modified) glasionomer cement. Attachment through adhesion can be performed with composite cement. If the hard tooth tissue is prepared adequately, composite cement provides sufficient adhesion, but self-adhesive composite cement is now also available. For the adhesion of the composite cement to the restorative materials of the single- or multi-unit fixed dental prosthesis, surface sandblasting, silanizing, and tin coating and the application of a metal primer or chemically active composite are available. Cementing a single- or multi-unit dental prosthesis involves 3 phases: 1. Cleansing the single- or multi-unit dental prosthesis and the abutment tooth/teeth; 2. Preparing the hard tooth tissue, mixing the cement and placing the single- or multi-unit dental prosthesis; 3. Removing the excess cement.

[Build-up restorations after extensive loss of tooth tissue]. / Funderings restauraties bij uitgebreid weefselverlies van gebitselementen.

After (extensive) loss of tooth tissue, vital teeth can be built up completely with composite restoration material. Sometimes, the application of additional retentive preparations is indicated. In exceptional cases, a root canal treatment is indicated, following which a root canal post is applied if necessary. Endodontically treated multi-rooted teeth can be built up entirely with composite, utilizing the pulp chamber and root canal accesses for retention. However, in single-rooted teeth a root canal post is necessary, in which case a prefabricated root post is used. Traditionally, metal posts were used in combination with a cast, indirect build-up restoration. Subsequently, directly fabricated cores, combining metal posts with amalgam or, at the present time, composite restoration material, became customary. The present trend is to use prefabricated or individually fabricated fibre-reinforced posts. After restoring a tooth with a build-up restoration, a combined build-up restoration can be chosen, or a direct or indirect crown single tooth prosthesis.

Clinical survival and performance of premolars restored with direct or indirect cusp-replacing resin composite restorations with a mean follow-up of 14 years.

OBJECTIVES: The objective is to evaluate the long-term clinical survival and performance of direct and indirect resin composite restorations replacing cusps in vital upper premolars. METHODS: Between 2001 and 2007, 176 upper premolars in 157 patients were restored with 92 direct and 84 indirect resin composite restorations as part of an RCT. Inclusion criteria were fracture of the buccal or palatal cusp of vital upper premolars along with a class II cavity or restoration in the same tooth. RESULTS: Forty patients having 23 direct and 22 indirect composite restorations respectively, were lost to follow-up (25.6%). The cumulative Kaplan-Meier survival rates were 63.6% (mean observation time: 15.3 years, SE 5.6%) with an AFR of 2.4% for direct restorations and 54.5% (mean observation time: 13.9 years, SE: 6.4%) with an AFR of 3.3% for indirect restorations. The Cox regression analysis revealed a statistically significant influence of the patient's age at placement on the survival of the restoration (HR 1.036, p = 0.024), the variables gender, type of upper premolar, type of restoration, and which cusp involved in the restoration had no statistically significant influence. Direct composite restorations failed predominantly due to tooth fracture, indirect restorations primarily by adhesive failure (p < 0.05). SIGNIFICANCE: There was no statistically significant difference in survival rates between direct and indirect composite cusp-replacing restorations. Both direct and indirect resin composite cusp-replacing restorations are suitable options to restore compromised premolars. The longer treatment time and higher costs for the indirect restoration argue in favor of the direct technique.

[Education and dental practice offer possibilities to exchange competences]. / Onderwijs en praktijk bieden mngelijkheden tot uitwisseling van vaardigheden.

The 3 dental schools in the Netherlands have the same goals for their graduates, in terms of knowledge and skills, but the contents of the curricula are different. The curricula are all based on the pillars of scientific education, medical education, dental education, and professionalism. Within this construction a student is trained as the manager of an oral health team. At graduation, the new generation of dentists have many (new) competences and relatively limited clinical experience and need support in acquiring clinical experience. Moreover, dentists who have recently graduated may be faced with methods and materials to which they were not introduced in their educational programme. A dentist with considerable clinical experience can test the newly acquired competences of the new generation ofdentists, with the benefit of a critical eye, against (routine) daily practices.

[The integration of science in the clinical dental programme at the University of Nijmegen]. / Integratie van wetenschap in de kliniek van de Nijmeegse opleiding tandheelkunde.

To be able to make a well founded clinical decision on the basis of evidence, the concept of 'evidence based practice' offers a solution by making it possible to select the appropriate knowledge from the increasing amount of scientific clinical information. Competence is required to put the concept (combining the best available scientific clinical evidence, experience and skills of the dentist and preferences of the patient) into practice. To prepare the undergraduate student for future clinical practice, the Nijmegen dental school has adopted evidence based practice to be implemented from the first year of dental training. The experiences of both students and lecturers are modest. The probable reason is that many clinical decisions are (can be) taken on the basis of experience and routine. The challenge is to base life-long learning on the practice of evidence based dentistry.

Randomized controlled trial on the performance of direct and indirect composite restorations in patients with severe tooth wear.

OBJECTIVE: The study aimed to evaluate survival and failure behavior of Direct Composite Restorations (DRC) and Indirect Composite Restorations (ICR) on molars and anterior teeth, in a Randomized Controlled Trial (RCT). METHODS: Patients with generalized severe tooth wear were included, and randomly assigned to one of 2 protocols: (1) DCR: All teeth were restored with directly applied micro-hybrid composite restorations (Clearfil AP-X, Kuraray) for load bearing areas and nano-hybrid composite restorations (IPS Empress Direct, Ivoclar Vivadent) for buccal veneers; (2) ICR: First molars were restored with indirect composite 'tabletop' restorations and maxillary anterior teeth were restored with indirect palatal veneer restorations (Clearfil Estenia C&B, cemented with Panavia F, Kuraray). Remaining teeth were restored directly. Restorations were evaluated after 3 years, focusing on clinical acceptability. Statistical analysis was performed using Kaplan Meier curves, Annual Failure Rates (AFRs), and univariate Cox regression analyses (p < 0.05). RESULTS: 41 patients (age: 36.6 ± 6.6y) were evaluated after 3 years (40.0 ± 2.2 m). 408 restorations on first molars and palatal veneers on maxillary anterior teeth were part of this RCT, with 220 DCRs and 188 ICRs. No differences in survival between treatment modality for palatal veneers for any failure criteria were found. Tabletop restorations on first molars showed a considerable higher failure rate for ICR compared to DCR (p = 0.026, HR: 3.37, 95%CI = 1.16-9.81). SIGNIFICANCE: In this RCT, directly applied composite restorations showed superior behavior compared to the indirect composite restorations, when used in the molar region.

Systematic review of the prevalence of tooth wear in children and adolescents.

Data on the prevalence of tooth wear among children and adolescents are inconsistent. Given the impact of extensive tooth wear for over a lifetime, evidence on the extent is required. The aim was to systematically review the literature on the prevalence of tooth wear in children and adolescents. A PubMed literature search (1980-2008) used the keywords 'tooth' AND 'wear'; 'dental' AND 'attrition' AND 'prevalence'; 'dental' AND 'wear' AND 'prevalence'; 'erosion AND prevalence' AND 'abrasion AND prevalence'. Following exclusion criteria, 29 papers were reviewed using established review methods. There was a total of 45,186 subjects (smallest study 80 and largest study 17,047 subjects) examined from thirteen multiple random clusters, eight multiple convenience clusters and eight convenience clusters. Nine different tooth wear indices were used, but the common denominator among studies was dentin exposure as an indicator of severe wear. Forest plots indicated substantial heterogeneity of the included studies. Prevalence of wear involving dentin ranged from 0 to 82% for deciduous teeth in children up to 7 years; regression analysis showed age and wear to be significantly related. Most of the studies in the permanent dentition showed low dentin exposure, a few reported high prevalence (range 0-54%); age and wear were not related (regression analysis). The results of this systematic review indicate that the prevalence of tooth wear leading to dentin exposure in deciduous teeth increases with age. Increase in wear of permanent teeth with age in adolescents up to 18 years old was not substantiated.

[Efficiency of fixed partial dentures]. / Doelmatigheid van bruggen.

A proposal for restorative treatment is based on the expected efficiency of the treatment. Efficiency is determined by measuring the investment, such as the monetary and biological cost, against what is gained, such as functional restoration and durability. If one's goal is to save tooth tissue in the restorative process, it is interesting to compare the conventional fixed partial denture with the adhesive fixed partial denture. The mean survival rate of conventional fixed partial dentures clearly exceeds the mean survival rate of adhesive fixed partial dentures but there are biological risks. Loss of vitality of the abutment teeth and the occurrence of caries are more prominent with conventional fixed partial dentures than with adhesive fixed partial dentures. Consequently, the possibility of replacing a conventional fixed partial denture with a new conventional fixed partial denture is limited. Because this and other clinical aspects can not easily be expressed numerically, the patient should be informed qualitatively about the advantages, disadvantages and uncertainties of the various types of fixed partial dentures.

Clinical performance of full rehabilitations with direct composite in severe tooth wear patients: 3.5 Years results.

OBJECTIVES: To evaluate the mid-term clinical performance of direct composite restorations placed in patients with pathological tooth wear needing full rehabilitation with an increase of vertical dimension of occlusion. METHODS: In a prospective trial 34 patients (34.0 ±â€¯8.4 years; 25 males, 9 females) were treated with a minimal invasive additive technique using composite restorations. The restorative treatment protocol was to provide all teeth with composite build-up restorations in an increased vertical dimension of occlusion (VDO) using the DSO-technique. Recall appointments were planned after 1 month, 1 and 3 years after treatment. Restorations were scored for clinically acceptability (FDI-criteria) and scores 4 and 5 were recorded as clinically unacceptable. Frequencies of failures and Kaplan Meier survival curves are presented and effect of relevant variables was calculated with a multifactorial Cox regression (p < 0.05). RESULTS: 1256 Restorations were placed, 687 anterior, 324 premolar, and 245 molar restorations. After a mean observation time of 39.7 months a total of 69 failures were observed, of which 61 restorations were repaired (score 4) and 8 were replaced (score 5). Most common reasons for failure were (chip) fractures (n = 43) and caries (n = 11). Placement of anterior restorations in two sessions led to significant 4.6 times more failures then placed in one session. CONCLUSIONS: In patients with severe tooth wear a full rehabilitation, in an increased vertical dimension of occlusion, direct composite resin restorations show a 94.8% success and 99.3% survival rate after a period of 3.5 years.

Signs and symptoms related to temporomandibular disorders--Follow-up of subjects with shortened and complete dental arches.

OBJECTIVE: To assess prevalence of cardinal signs and symptoms related to temporomandibular disorders (TMD) in subjects with shortened dental arches and to clarify the individual course of these signs and symptoms. METHODS: In this 9-year follow-up study, subjects with shortened dental arches (n=74) were compared with subjects with complete dental arches (n=72). Of three reported symptoms (pain, noises/clicking and restricted mobility of the lower jaw), and of two clinical signs (palpated clicking of the temporomandibular joint and restricted maximal mouth opening) estimates of mean scores were calculated by a mixed model. Suggested determinants for TMD (gender, time, bruxism, chewing side preference) were investigated by covariate analyses. Subjects with complete 9-year follow-up (shortened dental arches: n=42; complete dental arches: n=41) were described more detailed by frequency distributions, Pearson correlations of signs and symptoms, and fluctuation of the symptoms. RESULTS: Covariate analyses using the mixed model revealed no significant differences between the shortened and the complete dental arch groups (p>0.05) with respect to symptoms and signs. Most prevailing effect was gender: females reported more frequently pain (p=0.05) and noises/clicking (p=0.03). Restricted mobility was significantly related with chewing side preference and bruxism habits (both: p=0.01). In both groups, subjects with complete 9-year follow-up had low prevalence of serious symptoms and signs and symptoms fluctuated without demonstrable correlation. CONCLUSION: In this 9-year follow-up, subjects with shortened dental arches had similar prevalence, severity, and fluctuation of signs and symptoms related to TMD compared to subjects with complete dental arches.

A comparison of fatigue resistance of three materials for cusp-replacing adhesive restorations.

OBJECTIVES: To investigate the fatigue resistance and failure behaviour of cusp-replacing restorations in premolars using different types of adhesive restorative materials. METHODS: A class 2 cavity was prepared and the buccal cusp was removed in an extracted sound human upper premolar. By using a copy-milling machine this preparation was copied to 60 human upper premolars. In groups of 20 premolars each, direct resin composite restorations, indirect resin composite restorations and ceramic restorations were made. All restorations were cusp replacements made in standardized shape and with adhesive techniques. Cyclic load (5 Hz) was applied starting with a load of 200 N (10,000 cycles) followed by stages of 400, 600, 800 and 1000 N at a maximum of 50,000 cycles each. Samples were loaded until fracture or to 2,10,000 cycles maximum. In case of fracture, the failure mode was recorded. RESULTS: No differences were seen in fracture strength between the three groups (Wilcoxon P = 0.16). No differences were observed with regard to failure mode above or below the cemento enamel junctions (chi2 P = 0.63). The indirect resin composite and ceramic restorations showed significantly more combined cohesive and adhesive fractures than the direct resin composite restorations, which showed more adhesive fractures (chi2 P = 0.03 and 0.002). CONCLUSIONS: The results of this study suggest that ceramic, indirect resin composite and direct resin composite restorations provide comparable fatigue resistance and exhibit comparable failure modes in case of fracture, although the indirect restorations tend to fracture more cohesively than the direct restorations.

[In vitro fracture behaviour of composite crowns with and without posts]. / In vitro faalgedrag van composietkronen met en zonder stift.

The failure load and failure mode of severely damaged endodontically treated maxillary premolars were examined within a laboratory study. The premolars were divided into 4 groups. The first of which was restored with prefab metal posts, the second with prefab fibre posts and the third with custom-made fibre posts; all 3 receiving direct resin crowns. In a 4th (control) group no post-space preparation was performed and no posts were placed; a direct resin composite complete crown was made. After thermocycling, all specimens were statically loaded in a universal test machine until failure, under an angle of 30 degrees. There was no significant difference between the mean failure loads. Failure was merely due to unfavourable, non-repairable fractures (ending below the simulation of bone level). This study suggests that posts are not necessarily required to increase the failure load of direct resin composite crowns, however, clinical studies are necessary to confirm these findings.