Nico Creugers - Academia.edu (original) (raw)

Papers by Nico Creugers

Children (Basel), Jun 30, 2023

This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY

Journal of the Mechanical Behavior of Biomedical Materials

To compare the biomechanical properties of different endocrown designs on endodontically treated ... more To compare the biomechanical properties of different endocrown designs on endodontically treated teeth with an extensive defect in the mesial wall using a three-dimensional finite element method (3D FEM). Methods: Four finite element analysis models were designed and built up based on different endocrown configurations in a mandibular molar. One model was designed as a butt joint preparation with 2 mm occlusal thickness(control), the other three models were butt joint designs with different distances between the bottom of the mesial wall preparation and the cemento-enamel junction (CEJ): 2 mm, 1 mm and 0 mm respectively. A vertical load parallel with the longitudinal axis of the tooth and an oblique load with a 45 • angle to the longitudinal axis were applied to the occlusal surfaces. The maximum Von Misses (VM) stresses and stress distribution patterns were calculated and compared. Weibull risk-of-rupture analysis was used to analyze the survival probability of the restorations and tooth in the different models. Results: For the restoration, the model with a mesial wall destruction at the level of CEJ showed much higher risk of failure than other models. Overall, none of the four models showed failure. Under oblique loading, VM stress in the cement layer of the models with a mesial wall defect was higher than in the control model. In the dentin, the highest VM stresses were found in the peri-cervical dentin. Under the oblique loading, the model with the mesial wall destruction at the level of CEJ restored by endocrown showed the highest risk of failure. Conclusion: Under the oblique loading, with the increase of the simulated defect in the mesial wall, the peak VM stress values in the cement layer increased accordingly. In the model with a mesial wall defect up to the level of CEJ risk of failure was highest in the cervical dentin.

$Research paper thumbnail of A survey of cusp fractures in a population of general dental practices$

The International journal of prosthodontics

This study was conducted to expand the knowledge on the incidence of complete cusp fractures of p... more This study was conducted to expand the knowledge on the incidence of complete cusp fractures of posterior teeth in Dutch general practices. During a 3-month period, data were obtained from 28 general practitioners, representing 46,394 patients. For each new case of complete cusp fracture, clinicians recorded information using a standard form with questions relating to location of the fracture, cause of fracture, and restorative status of the tooth prior to the cusp fracture. There were 238 cases of complete cusp fracture recorded. The results of this study indicate an incidence rate of cusp fractures of 20.5 per 1,000 person-years at risk. Molars were more frequently registered with cusp fractures than premolars (79% vs 21%). Maxillary molars presented more fractures of buccal cusps (66% vs 34%), while mandibular molars presented more fractures of lingual cusps (75% vs 25%). Almost 77% of the cases had been restored on three or more surfaces. Statistical analysis revealed a positive...

Health and Quality of Life Outcomes, 2010

Clinical Oral Investigations, 2012

Clinical Oral Investigations, 2011

Clinical Oral Investigations, 2013

Objectives The objective of this study was to investigate the clinical course of shortened dental... more Objectives The objective of this study was to investigate the clinical course of shortened dental arches ('SDA group') compared to SDAs plus removable denture prosthesis ('SDA plus RDP group') and complete dental arches ('CDA group', controls). Materials and methods Data (numbers of direct and indirect restorations, endodontic treatments, tooth loss and tooth replacements) were extracted from patient records of subjects attending the Nijmegen Dental School who previously participated in a cohort study on shortened dental arches with three to four posterior occluding pairs (POPs). Results Records of 35 % of the original cohort were retrievable. At the end of the follow-up (27.4±7.1 years), 20 out of 23 SDA subjects still had SDA with 3-4 POPs compared to 6 out of 13 for SDA plus RDP subjects (follow-up 32.6±7.3 years). Sixteen out of 23 CDA subjects still had CDA; none of them lost more than one POP (follow-up 35.0±5.6 years). SDA group lost 67 teeth: 16 were not replaced, 16 were replaced by FDP and 35 teeth (lost in three subjects) replaced by RDP. Mean number of treatments per year in SDA subjects differed not significantly compared to CDA subjects except for indirect restorations in the upper jaw. Conclusion Shortened dental arches can last for 27 years and over. Clinical course in SDA plus RDP is unfavourable, especially when RDP-related interventions are taken into account. Clinical relevance The shortened dental arch concept seems to be a relevant approach from a cost-effective point of view. Replacement of absent posterior teeth by free-end RDP cannot be recommended.

Journal of child neurology, Jan 19, 2015

Duchenne muscular dystrophy patients report masticatory problems. The aim was to determine the ef... more Duchenne muscular dystrophy patients report masticatory problems. The aim was to determine the efficacy of mastication training in Duchenne muscular dystrophy using chewing gum for 4 weeks. In all, 17 patients and 17 healthy age-matched males participated. The masticatory performance was assessed using a mixing ability test and measuring anterior bite force before, shortly after and 1 month after the training. In the patient group the masticatory performance improved and remained after 1-month follow-up, no significant changes in anterior maximum bite force was observed after mastication training. In the healthy subject the bite force increased and remained at the 1-month follow-up; no significant differences in masticatory performance were observed. Mastication training by using sugar-free chewing gum in Duchenne muscular dystrophy patients improved their masticatory performance. Since bite force did not improve, the working mechanism of the improvement in chewing may relate to cha...

Journal of Oral Rehabilitation, 1993

During the period 1974-1986, 112 post and core build-ups were inserted in 74 patients. The build-... more During the period 1974-1986, 112 post and core build-ups were inserted in 74 patients. The build-ups consisted of a metal prefabricated post (Dentatus, Unimetric or Radix) in combination with a composite core. After an average follow-up period of 7.9 years, 14 failures (12.5%) were noticed. Eight teeth could be rerestored and six teeth had to be extracted. However, when correction was made for teeth with a bad initial prognosis and for extractions not related to the build-up restoration, eight failures remained caused by failure of the build-up (7.5%). The Dentatus posts seemed to increase the risk for failure.

Journal of dentistry, 2000

To assess the evidence on single-tooth restorations (STRs) supported by implants, and to aggregat... more To assess the evidence on single-tooth restorations (STRs) supported by implants, and to aggregate overall survival results. Searching MEDLINE was searched from 1990 to April 1998 using the terms 'dental in SB', 'implant*' and 'single'. Conference abstracts and non-English language papers were excluded. Study selection Study designs of evaluations included in the review The authors did not specify a study design in their inclusion criteria. Specific interventions included in the review STRs supported by implants. Participants included in the review Patients undergoing STRs supported by implants. Outcomes assessed in the review The outcomes were failure of the STR supporting implant (defined as a removed or lost implant), complications with the STR (dislodgement, screw loosening or screw fracture of the abutment or supporting crown), and crown completion. How were decisions on the relevance of primary studies made? Three of the researchers independently selected the studies. Consensus on selection was achieved through discussion. The agreement on each selection item was measured using the Cohens kappa-coefficient (see Other Publications of Related Interest no.4). Assessment of study quality Validity was assessed formally using a modification of the quality scoring system described by Antczak et al. and Kreulen et al. (see Other Publications of Related Interest nos.1-3). The studies were evaluated as to whether they represented good scientific practice (GSP), on the basis of criteria covering the areas of study methodology, dental methodology, evaluation methodology, and statistical methodology. Each criteria was marked with 3 points for full credit, 2 points for partial credit and 1 point for no credit. The total criteria score for each study was transferred to a scale from 0 to 1, and the result referred to as the 'GSP-score'.

Journal of Dentistry, 1997

European Journal of Dental Education

INTRODUCTION Changes in society, new public demands for dental care and contemporary educational ... more INTRODUCTION Changes in society, new public demands for dental care and contemporary educational insights have influenced dental education worldwide and demand a renewed perspective. Following this perspective, an innovative interprofessional dental Master curriculum was developed at Radboud University Nijmegen in the Netherlands. EDUCATIONAL PRINCIPLES The curriculum is based on five contemporary educational principles and the core of the curriculum consists of a Student Run Dental Clinic that is fully run by students under professional supervision. THE NEW CURRICULUM In the Student Run Dental Clinic, Master dental students and Bachelor oral hygiene students are responsible for the care of approximately 750 patients. The students work within the same clinic for three years and patients receive oral health care from the same students over a long period. The clinic is a longitudinal cross-disciplinary clinic with different dental subdisciplines. Entrustable professional activities (also known as EPAs), to our knowledge not yet widely used in dental education, were introduced to facilitate learning and assessment. Fourteen EPAs have been developed to stimulate interprofessional education and learning. Of these, five EPAs are identical for the dental and oral hygiene curriculum, leading to extended interprofessional education and learning in the Student Run Dental Clinic. DISCUSSION Preliminary results show that EPAs are generally well received by supervisors and students. CONCLUSION To monitor and investigate the exact effect of the interventions and underlying mechanisms, a research program on interprofessional learning, practice based learning and EPAs and entrustment in dental education was recently set up.

Journal of dental research, 1994

A clinical trial of 201 posterior resin-bonded bridges (PRBBs) was conducted partially in a Unive... more A clinical trial of 201 posterior resin-bonded bridges (PRBBs) was conducted partially in a University clinic and partially in general dental practices, for study of the influence of some experimental variables on the survival of these restorations. This report contains the results of an interim analysis which was done after 2.5 years' follow-up. No significant differences were found among the bonding systems used to adhere the PRBBs (Clearfil F2/etching, Panavia EX/sandblasting, and Microfill Pontic C/silicate-coating), or among the different preparation forms. PRBBs made in general dental practices were as retentive as those made in the University clinic. The "location" factor was found to be highly significant (p = 0.0001). The survival rates were 81% for maxillary PRBBs and 56% for mandibular PRBBs.

Journal of dental …, 1998

Previous clinical observations have revealed that resinbonded bridges for posterior tooth replace... more Previous clinical observations have revealed that resinbonded bridges for posterior tooth replacements are less retentive than anterior resin-bonded bridges. Improved bonding procedures and preparation designs, however, may have a positive effect on the functional durability of these restorations. The present study reports the final analysis of a randomized controlled clinical trial in which different designs of posterior resin-bonded bridges were evaluated for a period of at least 5 years. The operational hypothesis was that the bonding system and the preparation design used in posterior resin-bonded bridges have an influence on the survival and clinical functioning of these restorations. Survival in this study was defined at two levels: (1) 'complete' survival (survival without any debonding), and (2) 'functional' survival (survival including loss of retention on one occasion and successful rebonding of the original RBB without further debonding). With regard to 'complete' survival, no significant differences were found between the bonding systems used for adherence of the restorations to abutment teeth (etching/Clearfil F2, sandblasting/Panavia EX, and silica-coating/Microfill Pontic C). The variable 'preparation form' (conventional preparation form vs. modified preparation form) for complete survival was statistically in favor of the modified preparation form (62% vs. 46%), but did not influence the functional survival. With regard to 'functional' survival, the combination of silica coating and Microfill Pontic C was more retentive than the other bonding systems (90% survival vs. 72% and 75%, p < 0.01). Factor location was found to be highly significant for both survival levels [Cox's PH model, p = 0.0002 (Cox, 1972)]: The five-year 'complete' survival rates were 65% for maxillary restorations and 40% for mandibular restorations, while the five-year 'functional' survival rates were 89% and 68%, respectively. It is concluded that preparation of grooves in abutment teeth for posterior resinbonded bridges is beneficial to their chance of survival. Resinbonded bridges placed in the maxilla have a better prognosis than those made in the mandible. The bonding systems used in this study appear to have no influence on the chance of failure. In rebonded posterior resin-bonded bridges, the bonding system silica-coating/Microfill Pontic C was more retentive than the other systems tested.

This part has been edited. We hope that it is clear now. 7. Was the questionnaire piloted before ... more This part has been edited. We hope that it is clear now. 7. Was the questionnaire piloted before the survey? This is an important step in questionnaire development and should be addressed in the paper. Yes. The text has been edited to address this point. 8. Socioeconomic status is not a demographic variable. Correct this in sentence 6 of the section 'Interview and clinical examination'. This has been corrected. 9. You mention inter-observer reliability tests were conducted. What about intra-observer reliability? 'Oral health' has been replaced by 'dental health' throughout the text. 3. The language of paper is poor and must be improved before any further decision. The manuscript has been edited. We hope that the quality of language is now acceptable. The text lacks some basic rules for scientific writing. The tense of verbs should be in past. The tense of verbs has been changed into past tense.

Journal of dentistry, 1999

To investigate the short term effects of gamma-irradiation and conventional freezing on the hardn... more To investigate the short term effects of gamma-irradiation and conventional freezing on the hardness of human dentine. Twenty-one dentine disks were produced by transverse sectioning 21 sound extracted human permanent molar teeth. The 2.1 mm thick disks were wet polished using 4000 grit polishing paper. Three lines were drawn dividing each disk into six symmetrical areas. Seven disks were randomly assigned for freezing in water at -18 degrees C for 12 days; seven were exposed to a single dose of 25.2 kGy gamma radiation in water; seven were kept in water at 20 degrees C for 12 days (control). Before treatment, three Vicker&amp;#39;s indentations at a load of 30 kg and a dwelling time of 20 s were made in one half of each disk, at equal distances from its edge and centre. Using light microscopy and image analysis software, the indentation diagonals were measured 4 h after preparation. Vicker&amp;#39;s hardness values (VHN = kg/mm2) were calculated for each indentation. Following the treatment, VHNs were calculated again, for three symmetrical indentations in the second half of each disk. A statistical analysis was performed using the Wilcoxon rank sum test. The frozen group showed no changes following the treatment (VHN = 58 +/- 6 before vs. 57 +/- 6 after). The irradiation and control groups showed some hardening (VHN = 53 +/- 7 vs. 59 +/- 8; 57 +/- 3 vs. 63 +/- 6, respectively), however all values were within the normal variation. Both conventional freezing at -18 degrees C for 12 days in water, and a single gamma-irradiation dose of 25.2 kGy in water, appeared to have no short term effects on the hardness of human coronal dentine.

BMC Oral Health, 2010

BACKGROUND: Before strategies or protocols for oral health care can be advised at population leve... more BACKGROUND: Before strategies or protocols for oral health care can be advised at population level, epidemiological information on tooth decay patterns and its effects on oral function are indispensable. The aim of this study was to investigate influences of socio-demographic variables on the prevalence of decayed, missing, filled (DMF) and sound teeth (St) and to determine the relative risk of

$Research paper thumbnail of Ex vivo fracture resistance of direct resin composite complete crowns with and without posts on maxillary premolars$

International …, 2005

To investigate ex vivo the fracture resistance and failure mode of direct resin composite complet... more To investigate ex vivo the fracture resistance and failure mode of direct resin composite complete crowns with and without various root canal posts made on maxillary premolars. The clinical crowns of 40 human extracted single-rooted maxillary premolars were sectioned at the cemento-enamel junction. The canals were prepared with Gates Glidden drills up to size 4. Thirty samples were provided with standardized post spaces in the palatal canal and all roots were embedded in acrylic. Minimal standardized preparations in the canal entrances were made. Groups of 10 samples were treated with (i) prefabricated metal posts, (ii) prefabricated glass fibre posts, (iii) custom-made glass fibre posts, and (iv) no posts (control). Posts were cemented with resin cement and resin composite complete crowns were made. All specimens were thermocycled (6000x, 5-55 degrees C). Static load until fracture was applied using a universal loading device (crosshead speed 5 mm min(-1)) at a loading angle of 30 degrees . Failure modes were categorized as favourable and unfavourable failures. No significant difference was observed between the mean failure loads (group 1: 1386 N, group 2: 1276 N, group 3: 1281 N, and group 4: 1717 N, P &amp;gt; 0.05), nor between frequencies of failure modes (P &amp;gt; 0.05). All failures were fractures of the resin composite crown in combination with tooth material (cohesive failures). Within the limits of this laboratory investigation it is concluded that severely damaged and root filled maxillary premolars, restored with direct resin composite complete crowns without posts have similar fracture resistances and failure modes compared to those with various posts, which suggest that posts are not necessarily required.

Journal of Dentistry, 1998

A randomized controlled clinical trial was undertaken, to study the influence of some patient- an... more A randomized controlled clinical trial was undertaken, to study the influence of some patient- and operator-dependent variables on the survival of posterior resin-bonded bridges (PRBBs) and to assess the survival of replacement&amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; PRBBs. This report contains some of the results of the 5-year analysis. Survival was defined at three levels: (1) complete survival (without any debonding), (2) functional survival (i.e. survival after one loss of retention) and (3) replacement survival (survival of &amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;replacement&amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; PRBBs, inserted after rebonded bridges suffered a second dislodgement). Potential risk factors were analysed with Cox&amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s proportional hazards model and differences were tested for significance with the Breslow test. Observed effects are expressed as conditional-relative-risk (CRR). Survival of &amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;replacement&amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; PRBBs was assessed with the Kaplan-Meier method. Factors showing significant influences on complete survival were: &amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;location&amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; (highest risk for mandibular PRBBs: CRR = 2.2), &amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;aetiology&amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; (higher risk in treatment of aplasia: CRR = 2.9), and &amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;time of existence&amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; (open spaces existing less than 2 years before insertion of PRBB: CRR: 2.0). The factor &amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;large open spaces in the mandible&amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; was a risk for both complete and functional survival (CCR values 3.1 and 3.5, respectively). The survival of mandibular and maxillary &amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;replacement&amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; PRBBs after 5 years was 19 +/- 7% and 31 +/- 18%, respectively. Risk factors for PRBBs were: &amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;location&amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;, &amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;aetiology&amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;, &amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;time of existence&amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;, &amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;isolation method&amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; and &amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;large open spaces in the mandible&amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;. Mandibular &amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;replacement&amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; PRBBs showed such an unacceptably low survival rate that fabrication is not recommended.