Biomedical subjects

Bernd d'Hoedt

Publications and source records attributed to Bernd d'Hoedt.

9 recordsLinked to original sources

PubMed2003

Effect of low-level GaAlAs laser irradiation on the proliferation rate of human periodontal ligament fibroblasts: an in vitro study.

AIM: The aim of this in vitro study was to evaluate a potential stimulatory effect of low-level laser irradiation on the proliferation of human periodontal ligament fibroblasts (PDLF). MATERIALS AND METHODS: PDLF obtained from third molar periodontal ligaments were cultured under standard conditions and spread on 96-well tissue culture plates. Subconfluent monolayers were irradiated with an 809-nm diode laser operated at a power output of 10 mW in the continuous wave (cw) mode at energy fluences of 1.96-7.84 Jcm-2. The variable irradiation parameters were the time of exposure (75-300 s per well) and the number of irradiations (1-3). After laser treatment, the cultures were incubated for 24 h. The proliferation rate of the lased and control cultures was determined by means of fluorescence activity of a reduction-oxidation (REDOX) indicator (Alamar Blue Assay) added to the cell culture. Proliferation, expressed in relative fluorescence units (RFU), was determined 24, 48 and 72 h after irradiation. RESULTS: The irradiated cells revealed a considerably higher proliferation activity than the controls. The differences were significant up to 72 h after irradiation (Mann-Whitney U-test, p<0.05). CONCLUSION: A cellular effect of the soft laser application is clearly discernible. Clinical studies are needed to evaluate whether the application of low-level laser therapy might be beneficial in regenerative periodontal therapy.

Aluminum↗

PubMed2002

Effect of simulated CO2 and GaAlAs laser surface decontamination on temperature changes in Ti-plasma sprayed dental implants.

BACKGROUND AND OBJECTIVE: To investigate and compare temperature elevations at the implant-bone interface during simulated implant surface decontamination with a CO2 and a GaAlAs laser. STUDY DESIGN/MATERIALS AND METHODS: Stepped cylinder implants (Frialit 2) Friadent GmbH, Mannheim, Germany) with a Titanium plasma sprayed surface were inserted into bone blocks cut from pig femurs. An artificial periimplant bone defect provided access for laser irradiation in the coronal third. Both lasers were operated at 1.0-2.5 W in the cw-mode. The bone block was placed into a 37 degrees C water bath in order to simulate in vivo thermal conductivity and diffusitivity of heat. K-type thermocouples connected to a digital meter were used to register temperature changes at the periimplant bone. RESULTS: In mean, the critical threshold of 47 degrees C was exceeded after 8 seconds at a power output of 2.5 W, 13 seconds at 2.0 W, 18 seconds at 1.5 W, and 42 seconds at 1.0 W with the GaAlAs laser and 15 seconds (2.5 W), 23 seconds (2.0 W), 35 seconds (1.5 W), and 56 seconds (1.0 W) with the CO2 laser. At equal energy fluence, GaAlAs laser irradiation induced significantly higher temperature elevations than CO2 laser irradiation. CONCLUSIONS: In an energy dependent manner implant surface decontamination with both laser types must be limited in time to allow the implant and bone to cool down. Clinical guidelines are presented to avoid tissue damage.

Animals↗

PubMed2002

Low level 809-nm diode laser-induced in vitro stimulation of the proliferation of human gingival fibroblasts.

BACKGROUND AND OBJECTIVE: The authors investigated the effects of low level laser irradiation on the proliferation rate of human gingival fibroblasts (HGF) in vitro. STUDY DESIGN/MATERIALS AND METHODS: HGF were obtained from gingival connective tissue explants and cultured under standard conditions. 110 cell cultures in their logarithmic growth phase were spread on 96-well tissue culture plates and were irradiated at energy fluences of 1.96-7.84 J/cm(2). Another 110 cultures served as control. An 809-nm semiconductor laser operated at a power output of 10 mW in the cw-mode was used. The time of exposure varied between 75 and 300 seconds. Laser treatment was performed alternatively once, twice, and three times at a 24-hour interval. After lasing, incubation was continued for 24 hours. The proliferation rate was determined by means of fluorescence activity of a redox indicator added to the cell culture. Proliferation was determined 24, 48, and 72 hours after irradiation and expressed in relative fluorescence units (RFU). RESULTS: The irradiated cells revealed a considerably higher proliferation activity. The differences were highly significant 24 hour after irradiation (Mann-Whitney U-test, P < 0.05) but decreased in an energy-dependent manner after 48 and 72 hour after irradiation. CONCLUSIONS: A cellular effect of the soft laser irradiation on HGF is evident. Its duration, however, seems to be limited. These findings might be clinically relevant, indicating that repeated treatments are necessary to achieve a positive laser effect in clinical applications.

Cells, Cultured↗

PubMed2002

Randomized multicenter comparison of two coatings of intramobile cylinder implants in 313 partially edentulous mandibles followed up for 5 years.

Intramobile cylinder (IMZ) implants with either of two coatings, hydroxyapatite (HA) or titanium plasma-flame (TPF), as distal abutments for combined tooth implant-supported restorations, were compared in 313 partially edentulous mandibles with respect to postprosthetical failure patterns and complication frequencies in a randomized multicenter clinical trial. Within the treatment protocols, the two coatings do not show evidence of different efficacy with respect to occurrence of postprosthetical integration deficiency (ID) or functional deficiency (FD). Statistical equivalence for an absolute effect of +/-15% in event-free survival could only be demonstrated for FD, not for ID, however. Intent-to-treat and per-protocol population analyses gave consistent results. Hazards of occurrence of ID and FD, adjusted for years of follow-up, were estimated for ID as 7% per year (95%CI 4-10% per year) with HA and 5% per year (95%CI 3-7% per year) with TPF, and for FD as 5% per year (95%CI 3-7% per year) with HA and 4% per year (95%CI 2-6% per year) with TPF. The 5-year cumulative success rates for no ID were 69.5% (95%CI 58-81%) with HA and 82.2% (95%CI 74-91%) with TPF. With respect to frequencies of complications, there was no relevant statistically significant difference between the two coatings.

Adult↗

PubMed2002

B-mode versus A-mode ultrasonographic measurements of mucosal thickness in vivo.

OBJECTIVE: The objective of this study was to compare the measurement accuracy of A-mode and B-mode ultrasonographic assessments of palatal masticatory mucosal thickness in vivo. STUDY DESIGN: Thickness of palatal masticatory mucosa in the molar region of 50 volunteers was measured once with a B-mode ultrasound device (10 MHz) combined with a standoff for intraoral applications. At identical reading points thickness was also assessed with an A-mode device (5 replicates) and by needle probing for determination of true thickness. RESULTS: On average true thickness ranged between 2.9 and 3.3 mm (95% confidence intervals; median, 3.1 mm). B-mode ultrasonography overestimated truth by 0.19 mm (median) and differed significantly from truth (P =.008), whereas A-mode ultrasonography slightly underestimated true thickness by -0.05 mm (median). Limits of agreement were wider for A-mode ultrasonography (2.00 mm) than for B-mode ultrasonography (0.88 mm). CONCLUSIONS: Because accuracy of 0.2 mm is acceptable for many clinical indications, B-mode and A-mode yield sufficient accuracy for measurements of mucosal thickness.

Humans↗

PubMed2002

Bactericidal effect of the Er:YAG laser on dental implant surfaces: an in vitro study.

BACKGROUND: The aim of the in vitro study was to examine the bactericidal effect of an Er:YAG laser on common dental implant surfaces. METHODS: Seventy-two titanium platelets with 3 different surfaces--sandblasted and acid-etched (SA), titanium plasma-sprayed (TPS), and hydroxyapatite-coated (HA)--were incubated with a suspension of Streptococcus sanguinis (ATCC 10556). Irradiation at pulse energies of 60 and 120 mJ and a frequency of 10 pps was performed on a computer-controlled XY translation stage. After laser treatment the specimens were sonicated and the bacterial growth examined by counting colony forming units on blood agar plates. Temperature elevations during irradiation were investigated using K-type thermocouples. Laser treated implant surfaces were analyzed by means of electron microscopy. RESULTS: Compared to non-irradiated specimens, mean bacterial reductions of 99.51% (SA), 98.39% (HA), and 99.6% (TPS) at a pulse energy of 60 mJ and 99.92% (SA), 99.85% (HA), and 99.94% (TPS) at 120 mJ were calculated. At these laser parameters, no excessive temperature elevations or morphological implant surface alterations were detected. CONCLUSIONS: Even at low energy densities, the Er:YAG laser has a high bactericidal potential on common implant surfaces. Clinical studies are justified to evaluate the applicability and efficacy of the Er:YAG laser in the treatment of peri-implantitis.

Acid Etching, Dental↗

PubMedDate not supplied

Temperature changes at the implant-bone interface during simulated surface decontamination with an Er:YAG laser.

PURPOSE: This study investigated temperature changes at the implant-bone interface during simulated implant surface decontamination with an Er:YAG laser. MATERIALS AND METHODS: Stepped cylinder implants with three different surfaces (titanium plasma sprayed, sandblasted and acid etched, and hydroxyapatite coated) were placed in bone blocks cut from freshly resected pig femurs. An artificial periimplant bone defect with a size of 6 mm2 provided access for laser irradiation in the coronal third of the implant. A 540-pm periimplantitis application tip was used at a distance of 0.5 mm from the implant surface. Pulse energy was varied between 60 and 120 mJ at 10 pps. The bone block was placed into a 37 degrees C water bath to simulate in vivo thermal conductivity and diffusitivity of heat. K-type thermocouples connected to a digital meter were used to register temperature changes at three levels of the periimplant bone. RESULTS: The temperature at the implant-bone interface did not exceed 47 degrees C after 120 seconds of continuing laser irradiation. Temperature elevations were significantly higher at the hydroxyapatite-coated implants than in the two titanium surface groups (P < .001). CONCLUSION: Decontamination of implant surfaces by means of the Er:YAG laser did not excessively heat the periimplant bone within the energy range investigated. This technique therefore seems clinically safe, at least when used with the surfaces studied.

Acid Etching, Dental↗

PubMedDate not supplied

A 5-year longitudinal study of the clinical effectiveness of ITI solid-screw implants in the treatment of mandibular edentulism.

PURPOSE: The aim of this longitudinal study was to gain 5-year clinical documentation of the 1-stage surgical technique in connection with ITI solid-screw implants used in the edentulous mandible. MATERIALS AND METHODS: One hundred patients with totally edentulous mandibles were treated with bar-retained overdentures supported by a total of 340 consecutively placed ITI solid-screw implants. The patients were followed at annual intervals for at least 5 years to evaluate implant success, longitudinal reactions of the peri-implant hard and soft tissues, and incidences of biologic and mechanical complications. RESULTS: During the trial period, a total of 4 implants failed, all prior to loading, and 51 implants were lost to follow-up, resulting in a cumulative survival rate of 98.8% after 5 years of functional service. The success analysis included additional strictly defined events (either "first occurrence of marginal bone loss > or = 4 mm" or "first occurrence of pocket depth > or = 4 mm" and "first occurrence of crevicular fluid flow rate > or = 2.5 mm) and resulted in a cumulative 5-year success rate of 95.7%. The median marginal bone loss experienced between implant placement and prosthetic treatment was 0.5 mm, followed by an annual bone level change of 0.1 mm for the functional period of 5 years. The increasing incidence of remarkable plaque deposits from 19% to 50% represented the difficulties of the patients in maintaining a high level of oral hygiene, particularly for the lingual surfaces. Sulcus Bleeding Index, probing depth, attachment level, and crevicular fluid flow rate were used to describe the health of the peri-implant soft tissues and remained almost within acceptable standards. DISCUSSION: Survival and success rates of implants, amount of marginal bone loss, and periodontal indices of peri-implant soft tissues were consistent with those reported in the literature regarding implants with the submerged healing concept. CONCLUSION: With a cumulative survival rate of 98.8%, a cumulative success rate of 95.7%, and a median marginal bone loss of 0.5 mm during the healing period, followed by an annual rate of 0.1 mm after loading, non-submerged ITI solid-screw implants confirm the good clinical outcome of implant-supported treatment concepts for the rehabilitation of totally edentulous patients in a medium-term perspective.

Adult↗

PubMedDate not supplied

Residual ridge resorption in the edentulous maxilla in patients with implant-supported mandibular overdentures: an 8-year retrospective study.

PURPOSE: This retrospective study radiologically investigated alveolar bone resorption in the edentulous maxilla in patients with implant-supported mandibular overdentures. MATERIALS AND METHODS: This study consisted of 35 healthy, completely edentulous patients with a mean age of 59.7 years. They had received two implants between the mental foramina. New bar-retained mandibular overdentures and maxillary complete dentures were fabricated. Standardized panoramic radiographs taken subsequent to loading and at annual recall visits for up to 8 years were measured for alveolar bone loss in the maxilla. Bone areas and areas of reference not subject to resorption were measured with a planimetry program. The proportional value between both was expressed as a ratio (R). Bone loss was expressed as a change in R between two time points. Differences in the resorption rate between the anterior and posterior parts of the maxilla were investigated. RESULTS: Residual ridge resorption continued during the follow-up period and revealed high individual variability. With a range of 5% to 11% (median) loss in the original bone height, it was significantly (P < .031) more pronounced in the anterior than posterior maxilla (2% to 7%) from the second through eighth years. Regression analysis of the medians revealed a relatively high correlation between time and bone loss in both anterior and posterior parts of the maxilla. CONCLUSION: The anterior anchorage of mandibular overdentures by means of two implants and an ovoid bar was associated with slightly higher resorption in the anterior than in the posterior part of the edentulous maxilla.

Alveolar Bone Loss↗