Biomedical subjects

M Braem

Publications and source records attributed to M Braem.

At least 19 recordsLinked to original sources

PubMed2005

Micro-rotary fatigue of tooth-biomaterial interfaces.

The bonding effectiveness of restorative materials to tooth tissue is typically measured statically. Clinically tooth/composite bonds are however subjected to cyclic sub-critical loads. Therefore, in vitro fatigue testing of dental adhesives should predict better the in vivo performance of adhesives. The objective of this study was to determine the fatigue resistance of two representative adhesives, a self-etch and an etch&rinse adhesive, bonded to enamel and dentin. Therefore, tooth/composite interfaces were cyclically loaded using a miniaturized version of a rotating beam fatigue testing device. Subsequently, the load at which 50% of the specimens fail after 10(5) cycles, was determined as the median micro-rotary fatigue resistance (microRFR). For both adhesives, the microRFR was about 30-40% lower than the corresponding micro-tensile bond strength (microTBS) to both enamel and dentin. Analysis of the fracture surfaces by Feg-SEM revealed typical fatigue fracture patterns. It is concluded that resin/tooth interfaces are vulnerable to progressive damage by sub-critical loads, with the 3-step etch&rinse adhesive being more resistant to fatigue than the 2-step self-etch adhesive.

Adhesiveness↗

PubMed2005

A critical review of the durability of adhesion to tooth tissue: methods and results.

The immediate bonding effectiveness of contemporary adhesives is quite favorable, regardless of the approach used. In the long term, the bonding effectiveness of some adhesives drops dramatically, whereas the bond strengths of other adhesives are more stable. This review examines the fundamental processes that cause the adhesion of biomaterials to enamel and dentin to degrade with time. Non-carious class V clinical trials remain the ultimate test method for the assessment of bonding effectiveness, but in addition to being high-cost, they are time- and labor-consuming, and they provide little information on the true cause of clinical failure. Therefore, several laboratory protocols were developed to predict bond durability. This paper critically appraises methodologies that focus on chemical degradation patterns of hydrolysis and elution of interface components, as well as mechanically oriented test set-ups, such as fatigue and fracture toughness measurements. A correlation of in vitro and in vivo data revealed that, currently, the most validated method to assess adhesion durability involves aging of micro-specimens of biomaterials bonded to either enamel or dentin. After about 3 months, all classes of adhesives exhibited mechanical and morphological evidence of degradation that resembles in vivo aging effects. A comparison of contemporary adhesives revealed that the three-step etch-and-rinse adhesives remain the 'gold standard' in terms of durability. Any kind of simplification in the clinical application procedure results in loss of bonding effectiveness. Only the two-step self-etch adhesives approach the gold standard and do have some additional clinical benefits.

Adhesives↗

PubMed2004

A new method for semiautomatic analysis of surface EMG in patients with oral parafunctions.

Sleep-related phenomena or disorders, including snoring and tooth grinding, can be investigated using polysomnography. This method, however, generates large amounts of synchronically recorded data that are often analyzed visually with subjective interpretation. The purpose of this study was to minimize the need for subjective evaluation by developing a computer program for analysis of EMG data linked with polysomnographic recordings in a standardized and semi-automatic way. The selected algorithm differs from the Root Mean Square (RMS) method by being based on the theory of "differentiated EMG" (DIFEMG), which relies on two principles. The first says that the activation of a larger number of motor units results in a greater force production. The second principle says that the force production will continue for some time after the muscle is no longer stimulated. After a visual check for artifacts in the basic EMG recordings, the computer program is used to analyze the corrected basic EMG signal. The results were that both methods yield identical results as far as the detected number of events is concerned. There is, however, a significant difference when the duration of the events is considered, because the start and end of an event can be more accurately determined with the new method presented here. The computer program described will make comparison of data from different studies easier.

Algorithms↗

PubMed2004

[Inter-university cooperation in Flanders--an academic point of view on peer review].

Peer review as a possibility for discussion among practising dentists was introduced in Belgium in 1998 in the framework of a quality ensuring program. The 'Interuniversitary Cooperation', an initiative of Flemish universities active in teaching, research and patient treatment in dentistry has been involved in this program since its beginning to set up a dialogue between academia and dental practitioners and to gather information on scientific and educational matters. In this article the principles and organisation are described and thought is given to the attitude of the participants and future possibilities.

Belgium↗

PubMed2003

Root canal treatment performed by Flemish dentists. Part 1. Cleaning and shaping.

AIM: To gather information on root canal treatment carried out by dentists working in Flanders (Belgium). METHODOLOGY: A questionnaire was handed to 312 dentists attending peer review sessions organized by the Flemish Universities. Basic information (age, gender, year of graduation, practice profile) and information on various issues relating to the cleaning and shaping of root canals was collected. RESULTS: A total of 310 questionnaires were returned. The majority (85.7%) of respondents categorized themselves as general practitioners; 25.7% mentioned a clinical interest or speciality in practice. Most practitioners (64.5%) did not use rubber dam routinely during root canal treatment and performed treatment over two visits irrespective of the number of root canals. The majority of respondents (82.4%) used sodium hypochlorite as an irrigant, but 10.6% did not know the concentration they used; EDTA was used by 61.6%. The vast majority exposed a radiograph with an instrument of known length in situ to gauge the working length; only 3.6% relied on tactile sense; electronic root canal length determination was seldom used. Amongst the root canal instruments, K-files were used solely or in combination with other instruments by 60.3% of the respondents, reamers were used solely or in combination with other instruments by 55.4%. The stepback technique was used by 31.2% of the participants, a combination of stepdown and stepback by 26.4%, a reaming technique by 26.1% and the step-down technique by 14.7%. The majority were familiar with mechanical root canal Instruments. Almost half of the practitioners believed their preparation technique could be improved: only 1.3% felt that their procedures were poor. CONCLUSIONS: The results of this study indicate that the theoretical knowledge of dentists working in Flanders is good. However, the use of rubber dam remained low, half believed their preparation technique could be improved.

Belgium↗

PubMed2003

Endodontic treatment performed by Flemish dentists. Part 2. Canal filling and decision making for referrals and treatment of apical periodontitis.

AIM: To gather information on root-canal treatment carried out by dentists working in Flanders (Belgium). METHODOLOGY: A questionnaire reported in a previous study was also used to gather information on canal medicaments, canal filling, and in decision making for referrals and treatment of apical periodontitis. RESULTS: Calcium hydroxide as an interappointment dressing was used by 69.7% of the respondents. Approximately one-third of the respondents did not use any intracanal medicament. Caustic products used for pulp tissue fixation were used by 66.8% of the respondents. Cavit (48.2%) and glass-ionomer (31.3%) were the temporary coronal-filling materials used most often, followed by zinc oxide-eugenol and IRM(R). Cold lateral condensation of gutta-percha was the filling technique most used by the respondents (65.8%). Single-cone gutta-percha placement (16%), paste techniques (4.9%) and silver points (3.9%) were still used. Resin-based sealers were used most often (88.6%). Paraformaldehyde containing sealers such as Endomethasone and N2 were used infrequently. Approximately half of the practitioners were satisfied with their canal-filling technique, others felt that they could do better (43.0%); 0.7% were not satisfied. In cases with apical periodontitis, the size of periapical lesions and/or the presence of a root filling influenced the choice of endodontic treatment. The most common reasons for referral of endodontic cases were: retrieval of silver points, surgery, and post removal. CONCLUSIONS: The results of this study indicate that techniques and methods used for canal medication and canal filling were acceptable for the majority of the respondents. Re-treatment was underestimated as a treatment option.

Attitude of Health Personnel↗

PubMed2002

Influence of a bite-plane according to Jeanmonod, on bruxism activity during sleep.

One way to look at nocturnal oral parafunction such as bruxism, is using polysomnography. Although in recent years several studies have been carried out, it is almost impossible to compare the respective results because of the lack of standardization in the methodology used. The nocturnal muscular activity of m. Masseter and m. Temporalis Anterior has been registered in 21 patients suffering from bruxism, prior and after treatment with a bite-plane made according to Jeanmonod. A group of five persons without any dental or muscular parafunction has been included as a control. A computer program based on the biomechanical principles of muscle contraction has been developed and was used to analyse the raw electromyography (EMG) signal. The data shows a significant decrease (P = 0.008) in nocturnal parafunctional muscle activity with the bite-plane in situ. The present study shows that by analysing the raw signal obtained via EMG using a specially designed computer program, it becomes possible to isolate the occurrence of parafunctional events in the EMG signal and to study the influence of a given therapy on this EMG signal.

Adolescent↗

PubMed2001

Decreased amount of slow wave sleep in nocturnal bruxism is not improved by dental splint therapy.

OBJECTIVE: To test the efficacy of dental treatment of bruxism on sleep quality, using slow wave sleep as the primary outcome parameter. METHODS: The study design consisted of an open label, unpaired comparison between normals and patients and a paired comparison between pre- and post-treatment patient recordings. Twenty patients suffering from bruxism (13 male, 7 female, mean age 35 years) and 6 normal volunteers (3 male, 3 female, mean age 30 years) participated in the study. Polysomnographic recordings were performed in a sleep laboratory in a general hospital both before and after treatment. The treatment was derived from a model that ascribes bruxism to a dental malocclusion, and consisted solely of dental therapy (Jeanmonood 1988). RESULTS: The untreated bruxism group had worse sleep than normals when comparing slow wave sleep (21% versus 32% slow wave sleep percentage in sleep period time) during the second polysomnographic recording, after one night adaptation. Therapy did not improve sleep quality; bruxism patients showed only minor, non-significant differences in sleep quality when comparing pre- and post-treatment recordings.

Adult↗

PubMed2000

Surface contact fatigue and flexural fatigue of dental restorative materials.

Antagonistic contact on a dental restoration may produce surface and subsurface stresses leading to fatigue wear as well as to bulk stressing, eventually causing catastrophic failure. It was the aim of the present work to study the outcome of two different approaches to fatigue testing of materials involving either surface contact fatigue or flexural fatigue mechanisms. A range of materials was tested, including conventional glass-ionomers, resin-modified glass-ionomers, poly-acid modified composites, and composites. Materials were prepared and tested using both surface contact and flexural fatigue. The results show that conventional glass-ionomers have the least resistance to fatigue under both regimes while composites have the longest fatigue lives and the highest values of flexural fatigue limit. However, the results also support the fact that catastrophic failure should be investigated separately from surface contact fatigue. Within the group of composite products tested, a hybrid composite material had a significantly greater flexural fatigue limit than a microfilled one, but the latter material had a significantly greater surface contact fatigue life, indicating that wear behavior cannot be predicted from bulk fracture characteristics and vice versa. The process of wear occurs by a combination of a number of fundamental processes, and the contribution fatigue makes will vary according to the environment and nature of the material.

Dental Materials↗

PubMed1998

Immediate versus one-month wet storage fatigue of restorative materials.

Immediate finishing is a highly desirable property of restorative materials. In general, the resin composites, the polyacid-modified resin composites and resin-modified glass-ionomers are finished immediately after light-curing. For the conventional glass-ionomers a waiting period of 24 h is recommended. Therefore, the objective of this study was to investigate whether immediate finishing and application of cyclic loading under water spray on resin-modified glass-ionomers, a conventional glass-ionomer, a polyacid-modified resin composite and a resin composite are reflected in their Young's modulus and fatigue resistance after 1-month wet storage compared with a control group that could mature untroubled for 1 month. From this study, it could be concluded that there is a material-dependent response on immediate finishing. For the conventional glass-ionomer, the waiting period of 24 h is highly advisable. The resin composite suffered more than the other test materials. A second statement is that one must be cautious by the extrapolation of findings obtained on quasi static tests (Young's modulus) towards dynamic properties (flexural fatigue limit).

Biocompatible Materials↗

PubMed1997

Comparative physico-mechanical characterization of new hybrid restorative materials with conventional glass-ionomer and resin composite restorative materials.

The recently developed hybrid restorative materials contain the essential components of conventional glass ionomers and light-cured resins. The objective of this study was to determine several physical and mechanical properties of eight such materials in comparison with two conventional glass ionomers, one micro-filled, and one ultrafine compact-filled resin composite. The two resin composites and two of the three polyacid-modified resin composites could be polished to a higher gloss than the conventional as well as the resin-modified glass ionomers. After abrasion, surface roughness increased for all materials, but not at the same extent, being the least for the conventional resin composites and one polyacid-modified resin composite, Dyract. In contrast to the later resin composites, of which the surface roughness is principally determined by the presence of protruding filler particles above the resin matrix, roughness of conventional and resin-modified glass ionomers results from both protruding filler particles and intruding porosities. The mean particle size of the hybrid restorative materials fell between the smaller mean particle size of the resin composites and the larger one of the conventional glass ionomers. The micro-hardness and Young's modulus values varied substantially among all eight hybrid restorative materials. For all the resin-modified glass-ionomer restorative materials, the Young's modulus reached a maximum value one month after mixing and remained relatively stable thereafter. The Young's modulus of the conventional and the polyacid-modified resin composites decreased slightly after one month. The conventional glass-ionomer materials undoubtedly set the slowest, since their Young's modulus took six months to reach its maximum. The flexural fatigue limit of the hybrid restorative materials is comparable with that of the micro-filled composite. From this investigation, it can be concluded that the physico-mechanical properties vary widely among the eight hybrid restorative materials, indicating that these materials probably have yet to achieve their optimum properties. Their mechanical strength is inadequate for use in stress-bearing areas, and their appearance keeps them from use where esthetics is a primary concern.

Acrylic Resins↗

PubMed1996

Restorative therapy for erosive lesions.

More needs to be learned about the etiology of erosion lesions before they can be accurately diagnosed, confidently treated and, more importantly, prevented. The treatment is dependent on the location and the degree of erosion. The decision to treat an erosion lesion should be based on careful consideration of the etiology and progression of the condition. Reasons for restoring noncarious enamel/dentin lesions are discussed and various therapeutic measures are provided. Preventive and restorative therapeutic measures for noncarious abrasive/ erosive lesions are proposed such as: a change of dietary or behavior patterns; application of desensitization products; intensive fluoride therapy with or without iontophoresis; brushing with desensitizing dentifrices; adhesive penetration with dentin bonding agents; glass ionomers and compomers; resin composites; composite or porcelain veneers; crown and bridge work; occlusal adjustments and nightguard fabrication if the abfraction factor coincides. The clinical durability of restorative therapy and important clinical factors related to the restoration of multifactorial defects are discussed.

Composite Resins↗

PubMed1996

[Resin-modified glass-ionomers in dentistry].

The resin-modified glass-ionomers contain the essential components of both a conventional glass-ionomer and a visible light-cured resin. They have several advantages like longer working time, shorter setting time, bonding to tooth structure, fluoride-release, better aesthetics than conventional glass-ionomers and ease in use. As disadvantages can be mentioned the polymerisation shrinkage, trapping of air-bubbles, difficulties in colour choice and contouring. A physical and mechanical characterisation was necessary to define the possibilities and limits of these materials. It can be stated that the strength and aesthetic appearance of resin-modified glass-ionomers are less than that of composites, but better than that of conventional glass-ionomers. Clinically, this is expressed in a rough and dull surface compared to a composite restoration. They are not indicated in stress bearing areas. Consequently, they are mainly indicated in cervical class V-restorations in the postcanine region, and probably restorations in pedodontics, geriatric dentistry and for patients with a high caries activity.

Compomers↗

PubMed1996

[Characterization of resin-containing glass ionomers].

Recently, several new resin-modified glassionomers have been introduced on the dental market. At the moment a real confusion exists over the right terminology of the products and its limits in use. Therefore, an in vitro and in vivo study with simultaneously a comparison with conventional glassionomers and composite resins was really necessary. This study revealed that resin-modified glassionomers have physico-mechanical properties that are situated between those of conventional glassionomers and composite resins. The manufacturers have a different approach concerning the particle size distribution. The new materials give a rough surface. They are not indicated for posterior restorations, because their surface hardness is too low compared to that of enamel, and their fatigue resistance is insufficient. The elasticity decreases during setting and maturation. Consequently, they are mainly indicated in situations that require a moderate strength and esthetics, for patients with a high caries activity and when ease in use is requested.

Composite Resins↗

PubMed1996

The interaction of adhesive systems with human dentin.

PURPOSE: To investigate the interaction of six experimental and commercial bonding systems with dentin in vivo. MATERIALS AND METHODS: One-Step, Clearfil Liner Bond 2, OptiBond, Permagen with 10% phosphoric acid, Permagen with 35% phosphoric acid, and Prime & Bond were applied in standard Class I occlusal cavities in premolars scheduled for extraction for orthodontic reasons, combined either with a self-cured or with a light-cured resin composite. The teeth were carefully extracted 5 minutes after resin polymerization and fixed in 2.5% glutaraldehyde. After fixation, the specimens were dehydrated, sectioned, and processed for field-emission SEM. RESULTS: Although some systems produced gap-free intact interfaces in specific specimens, all of them showed detachment at the transition between the resin-dentin interdiffusion zone and the fluid resin placed over it. It was apparent that the presence of air-bubbles and/or thick layers of polymerized-filled fluid resin resulted in less frequent separation areas at the resin-dentin interface, providing support for the concept of the elastic cavity wall. It was also confirmed that some dentin adhesive systems do not form a thick layer over the dentin, otherwise the resin composite would not have penetrated the dentin tubules.

Adolescent↗

PubMed1996

Three-year clinical effectiveness of four total-etch dentinal adhesive systems in cervical lesions.

A 3-year follow-up clinical trial of two experimental Bayer total-etch adhesive systems and two commercial total-etch systems. Clearfil Liner Bond System and Scotchbond Multi-Purpose, was conducted to evaluate their clinical effectiveness in Class V cervical lesions. Four hundred twenty abrasion-erosion lesions were restored randomly using the four adhesive systems. There were two experimental cavity designs, in which the adjacent enamel margins either were or were not beveled and acid etched. Clearfil Liner Bond System and Scotchbond Multi-Purpose demonstrated high retention rates in both types of cavity design at 3 years. The two experimental Bayer systems scored much lower retention rates in both cavity designs at 3 years. None of the systems guaranteed margins free of microleakage for a long time. At 3 years, superficial, localized marginal discolorations were observed, the least for Clearfil Liner Bond System, followed by Scotchbond Multi-Purpose and the two experimental systems. Small marginal defects were recorded at the cervical dentin and the incisal enamel margin. Retention of Clearfil Liner Bond and Scotchbond Multi-Purpose appears to be clearly improved over earlier systems, but marginal sealing remains problematic. The two Bayer systems were found to be clinically unreliable.

Acid Etching, Dental↗

PubMed1996

[Characterization of glass ionomer cements containing resin].

Chemical Phenomena↗

PubMed1995

Clinical and semiquantitative marginal analysis of four tooth-coloured inlay systems at 3 years.

OBJECTIVES: The marginal quality of four tooth-coloured inlay systems was clinically investigated and subjected to computer-aided semiquantitative marginal analysis under scanning electron microscopy (SEM) after 3 years of clinical service. METHODS: Three of the restoration types were made using the Cerec CAD-CAM apparatus: one was milled from preformed glass ceramic blocks, and the two other inlay types were milled from preformed porcelain blocks. The fourth system was based on an experimental indirect resin composite inlay system. Each inlay type was luted with a different luting resin composite. The clinical evaluation was performed with a mirror and explorer by two clinicians separately, and the marginal analysis was conducted microscopically on replicas (SEM x 200). RESULTS: After 3 years in situ, all the restorations were clinically acceptable. No recurrent caries was observed. Marginal analysis under SEM detected a high percentage of submargination for all four systems, which suggests that their respective resin composite luting agents were all subject to wear. The percentage of marginal fractures on the enamel side as well as on the inlay side did not increase dramatically compared to the 6-month results. CONCLUSION: The first recall after 6 months of clinical service indicated how tooth-coloured inlays behave at their margins. The 3-year results confirmed the early findings, indicating that wear of resin composite lutes is important and present in all systems. The two ceramic materials showed a similar behaviour at the margins. The resin composite inlay performed better at the inlay site than at the enamel site.

Adult↗