Biomedical subjects

L Bergmans

Publications and source records attributed to L Bergmans.

7 recordsLinked to original sources

PubMed2006

Bactericidal effect of Nd:YAG laser irradiation on some endodontic pathogens ex vivo.

AIM: To define the role of neodymium:yttrium-aluminum-garnet (Nd:YAG) lasers in root canal disinfection along with a minimally invasive treatment concept. METHODOLOGY: The hypothesis was tested ex vivo that Nd:YAG laser irradiation has a bactericidal effect on endodontic pathogens inoculated in root canals. Resultant colony-forming unit counts were associated with observations of bacterial cell structural changes using conventional scanning electron microscopy (CSEM) and environmental scanning electron microscopy (ESEM) on inoculated dentine surfaces, following indirect and direct Nd:YAG laser irradiation, respectively. RESULTS: The Nd:YAG laser irradiation (1.5 W, 15 Hz, four times for 5 s) of Enterococcus faecalis inoculated canals resulted in a significant reduction (P < 0.05, Wilcoxon signed rank test) of the bacterial load, meaning a 99.7% kill, but no sterilization. The CSEM procedure verified that the extent of radiation damage was in line with the total amount of laser energy applied. After 2 h of incubation and three cycles of indirect laser treatment (i.e. through a 1-mm-thick dentine disc), no morphologically intact bacteria of Actinomyces naeslundii or Streptococcus anginosus were discernible. However, when micro-colonies of S. anginosus and specially biofilms of E. faecalis were present after 2 days, the in situ experiment using ESEM and direct laser treatment showed that bacterial eradication was reduced in deep layers. CONCLUSIONS: The Nd:YAG laser irradiation is not an alternative but a possible supplement to existing protocols for canal disinfection as the properties of laser light may allow a bactericidal effect beyond 1 mm of dentine. Endodontic pathogens that grow as biofilms, however, are difficult to eradicate even upon direct laser exposure.

Actinomyces↗

PubMed2005

Microscopic observation of bacteria: review highlighting the use of environmental SEM.

Throughout the years, various methods have been adopted to investigate bacteria involved in root canal infection and apical periodontitis. This paper reviews the most commonly used microscopic techniques and discusses their possibilities, limitations and sample preparation. In particular, a recently developed variant of scanning electron microscope (SEM), referred to as environmental SEM (ESEM), is highlighted due to its potential impact across the diverse field of biomaterials research. The performance of this ESEM technique for bacterial observation of endodontic pathogens was illustrated by a practical approach. The paper concludes with a discussion on the possible use of ESEM for testing endodontic treatment modalities under environmental conditions in situ.

Bacteria↗

PubMed2003

Progressive versus constant tapered shaft design using NiTi rotary instruments.

AIM: To evaluate the influence of a progressive versus constant tapered shaft design on canal preparation by NiTi rotary techniques. METHODOLOGY: A XMCT-scanner and custom-made software were used to nondestructively analyse the mesial canals of 10 extracted mandibular molars in 3D with a spatial resolution of 12.5 microm. Specimens (n = 10 per group) were scanned before and after preparation using ProTaper (progressive tapered) or K3 (constant tapered) files. Numerical values for volume, curvature, dentine removal and centring ratio were obtained in addition to a visual inspection for canal aberrations. Data were analysed by (multiway factorial) anova, Wilcoxon tests and t-tests. RESULTS: The volume of total dentine removal (mean +/- SD) was 1.21 +/- 0.66 mm(3) (ProTaper) and 1.06 +/- 0.23 mm(3) (K3) (P > 0.05), and the amount of dentine removal at all separate horizontal regions examined was comparable for both groups. The mean linear dentine removal (transportation) was in the range of 8-212 microm (ProTaper) and 4-187 microm (K3). The resultant centring ratio varied from 0.01 to 0.24 (ProTaper) and from 0.01 to 0.17 (K3), whilst different straightening patterns were observed. A centre displacement towards the furcation coronally was most pronounced for the ProTaper group whereas a centre displacement towards the outer side of the curvature more apically was only observed for the K3 group. No severe canal aberrations were found. CONCLUSIONS: The progressive tapered shaft design of the ProTaper instrument was less influenced by the mid-root curvature than the constant tapered design of the K3 instrument thereby providing a good centred apical preparation. However, ProTaper instruments tended to transport towards the furcation in the coronal region.

Analysis of Variance↗

PubMed2002

Cervical external root resorption in vital teeth.

External resorptions associated with inflammation in marginal tissues present a difficult clinical situation. Many times, lesions are misdiagnosed and confused with caries and internal resorptions. As a result inappropriate treatment is often initiated. This paper provides three-dimensional representations of cervical external resorption, based on X-ray microfocus-tomographical scanning of a case, which will aid the dental practitioner in recognizing characteristic features during clinical inspection. In addition, histopathological examination reveals the cellular morphology of the adjacent tissues.

Adult↗

PubMed2002

Smooth flexible versus active tapered shaft design using NiTi rotary instruments.

AIM: The aim of this study was to evaluate the influence of a smooth flexible versus active tapered shaft design on canal preparation by NiTi rotary techniques. METHODOLOGY: A XMCT-scanner (SkyScan 1072) and developed software (Bergmans et al. 2001) were used to nondestructively analyze the mesial canals of 10 extracted mandibular molars in 3D with a spatial resolution of 30 microm. Specimens (n = 10 per group) were scanned before (PRE) and after (POST) preparation using Lightspeed (smooth flexible) or GT-rotary (active tapered) files. Numerical values for volumes, dentine removal (net) transportation and centring ability were obtained in addition to a visual inspection on canal aberrations. Data were analyzed by Shapiro Wilk test, multiway factorial anova, Tukey-Kramer test, Wilcoxon test and t-test. RESULTS: Results indicated that the active tapered shaft removed significantly more dentine in the middle to apical portion of the root compared to the smooth flexible design. Both groups demonstrated some straightening, but no significant differences were found with respect to instrument types. However, absolute values for net transportation and centering ratio were small and no canal aberrations could be found. CONCLUSIONS: The smooth flexible shaft design did not improve the morphological characteristics of canal preparation by NiTi rotary instruments when compared with the active tapered design. Therefore, system selection should be based upon other criteria.

Analysis of Variance↗

PubMed2001

A methodology for quantitative evaluation of root canal instrumentation using microcomputed tomography.

AIM: The aim of this paper was to present an objective methodology for quantitative evaluation of root canal instrumentation using microcomputer tomography, together with developed software based on a constructed mathematical model. METHODOLOGY: A desktop X-ray micro-CT scanner (SkyScan 1072) was used to provide data sets of an extracted mandibular molar before and after instrumentation (ProFile 0.04 Taper instruments, Dentsply Maillefer, Ballaigues, Switzerland) that were stored for later use by software. A volume visualization package (T3D) was applied to obtain 3D renderings of the molar to illustrate the qualitative visualization capacity. Next, medical image volume fusion software was used to allow alignment of pre and post image volumes. Finally, software was developed to make quantitative measurements and to provide additional qualitative information on the registered image volumes. This procedure implemented a true 3D mathematical model for quantification of instrumentation effects. Using a local co-ordinate frame, perpendicular reslices were made at five different levels within the mesio-buccal canal to evaluate transportation and centring ability. RESULTS: At first accurate and detailed 3D renderings were obtained. The general and local canal shape before and after preparation could visually be examined in 360 degrees rotation. Numerical values were obtained for volume, volume changes and transportation. Centring ability was calculated by centring ratio and centre movement. CONCLUSIONS: This methodology is a new and objective way for quantitative evaluation of root canal instrumentation using microcomputer tomography and dedicated software.

Evaluation Studies as Topic↗

PubMed2001

Mechanical root canal preparation with NiTi rotary instruments: rationale, performance and safety. Status report for the American Journal of Dentistry.

The growing use of NiTi rotary instruments in dental practice demands a good understanding of their concept of alloy and design in relation to improved properties and inherent limitations. Nickel titanium's super elasticity allows more centered canal preparations with less transportation and a decreased incidence of canal aberrations. Furthermore, the production of files with increased taper became possible. This is of special importance because of concerns on the achievement of adequate irrigation and close adaptation of the filling material during endodontic treatment. Unique shaft and tip designs should permit the use of a rotary handpiece allowing different tactile awareness. On the other hand, special attention is paid to maximize cutting efficiency and cutting control throughout instrumentation. NiTi rotary instruments are generally used in a crown-down approach and a continuous reaming motion. Consequently, rounder root canal preparations, with less straightening and a smaller amount of apical extrusion is achievable. In spite of their increased flexibility, separation is still a concern with NiTi files. The phenomenon of repeated cyclic metal fatigue and the variable of torsional loading are two important factors in instrument fracture. However, with awareness of the appropriate manipulation and special attention to the equipment used, NiTi systems are safe with a minimal incidence of instrument failure.

Dental Alloys↗