Biomedical subjects

K Van Landuyt

Publications and source records attributed to K Van Landuyt.

At least 19 recordsLinked to original sources

PubMed2006

Effects of ceramic surface treatments on the bond strength of an adhesive luting agent to CAD-CAM ceramic.

OBJECTIVES: The objective of this study was to evaluate the effect of different surface treatments on the micro-tensile bond strength (microTBS) of an adhesive luting agent to CAD-CAM ceramic. The hypothesis tested was that neither of the surface treatments would produce higher bond strength of the adhesive luting agent to CAD-CAM ceramic. METHODS: Ceramic specimens of two different sizes (6 mm x 8 mm x 3 mm; 13 mm x 8 mm x 4 mm) were fabricated from ProCAD ceramic blocs (Ivoclar-Vivadent) with a low-speed diamond saw. The ceramic blocks were divided into seven groups and submitted to the following surface treatments: group 1: no treatment; group 2: etching with 37% H(3)PO(4); group 3: etching with 37% H(3)PO(4)+silane; group 4: etching with 37% H(3)PO(4)+silane+adhesive resin; group 5: etching with 4.9% HF acid; group 6: etching with 4.9% HF acid+silane; group 7: etching with HF acid+silane+adhesive resin. After surface treatment, two differently sized porcelain disks were bonded together with a composite luting agent (Variolink II, Ivoclar-Vivadent). The specimens were stored for 24h in distilled water at 37 degrees C prior to microTBS testing. One-way analysis of variance was used to test the influence of surface treatment and Scheffe multiple comparisons test determined pair-wise statistical differences (p<0.05) in microTBS between the experimental groups. RESULTS: The mean microTBSs (standard deviation) are: group 1: 12.8 (+/-4.6)MPa; group 2: 19.1 (+/-5.0)MPa; group 3: 27.4 (+/-11.1)MPa; group 4: 34.0 (+/-8.9)MPa; group 5: 37.6 (+/-8.4) MPa; group 6: 34.6 (+/-12.8)MPa; group 7: 34.5 (+/-5.1)MPa. Statistical significant differences were found between group 1 and groups 3-7, and between group 2 and groups 4-7. All specimens of groups 1-4 exhibited adhesive failures, while a combination of adhesive and mixed (adhesive and cohesive) failures was observed in the specimens of groups 5-7. CONCLUSIONS: The results show that surface treatment is important to bond to ceramic and suggests that etching is needed preferably with hydrofluoric acid than with phosphoric acid.

Acid Etching, Dental↗

PubMed2006

Free DIEAP and SGAP flap breast reconstruction after abdominal/gluteal liposuction.

Perforator flaps are widely used in our unit for breast reconstruction. They provide ample tissue with minimal donor site morbidity together with long lasting aesthetic results. Increasing number of patients may have liposuction procedure which may jeopardise areas such as the abdomen and the buttock which are the donor sites for perforator-free flaps in breast reconstruction. Therefore, liposuction has been considered as a relative contraindication of raising perforator flaps. Six patients who had previous liposuction of the donor sites underwent autologous breast reconstruction with perforator-free flaps. Colour Duplex imaging was obtained in all cases preoperatively in order to evaluate the blood supply to the flap and to map the perforators. There were five deep inferior epigastric artery flaps (DIEP) and one superior gluteal artery perforator (SGAP) flap used. Total flap survival was obtained in all cases. Postoperative course was uneventful. Our results showed that raising perforator flaps after liposuction of the donor sites is possible. Preoperative radiological evaluation of the perforators is mandatory for such difficult cases.

Abdominal Wall↗

PubMed2006

Bonding effectiveness of adhesive luting agents to enamel and dentin.

OBJECTIVES: The bonding effectiveness of five adhesive luting agents to enamel and dentin using different application procedures was determined using a micro-tensile bond strength protocol (microTBS). METHODS: Enamel/dentin surfaces of human third molars were flattened using a high-speed diamond bur. Composite resin blocks (Paradigm, 3M ESPE) were luted using either Linkmax (LM; GC), Nexus 2 (NX; Kerr), Panavia F (PN; Kuraray), RelyX Unicem (UN; 3M ESPE) or Variolink II (VL; Ivoclar-Vivadent), strictly following manufacturers' instructions. For some luting agents, modified application procedures were also tested, resulting in four other experimental groups: Prompt L-Pop+RelyX Unicem (PLP+UN; 3M ESPE), Scotchbond Etchant+RelyX Unicem (SE+UN; 3M ESPE), Optibond Solo Plus Activator+Nexus 2 (ACT+NX; Kerr) and K-Etchant gel+Panavia-F (KE+P; Kuraray). The experimental groups were classified according to the adhesive approach in self-adhesive (UN), etch-and-rinse (ACT+NX, NX, KE+P, SE+UN and VL when bonded to enamel) and self-etch adhesive luting agents (LM, PLP+UN, PN and VL when bonded to dentin). The specimens were stored for 24h in distilled water at 37 degrees C prior to microTBS testing. The Kruskal-Wallis test was used to determine pairwise statistical differences (p<0.05) in microTBS between the experimental groups. RESULTS: When bonded to enamel, ACT+NX (15 MPa) and UN (19.6 MPa) scored significantly lower than VL (49.3 MPa), LM (49.2 MPa), PN (35.4 MPa) and SE+UN (35.2 MPa), while PLP+UN (23.5 MPa) showed a significantly lower microTBS than VL (49.3 MPa) and LM (49.2 MPa). No significant differences were noticed between VL (49.3 MPa), LM (49.2 MPa), NX (37.9 MPa), KE+PN (38.8 MPa), PN (35.4 MPa) and SE+UN (35.2 MPa). Regarding the bonding effectiveness to dentin, all luting agents bonded equally effectively (UN: 15.9 MPa; LM: 15.4 MPa; PN: 17.5 MPa; NX: 22.3 MPa), except VL (1.1 MPa), SE+UN (5.9 MPa) and ACT+NX (13.2 MPa). VL revealed an exceptionally high number of pre-testing failures, most likely due to a combined effect of not having cured the adhesive separately and an insufficiently light-cured luting agent. SIGNIFICANCE: Following a correct application procedure, the etch-and-rinse, self-etch and self-adhesive luting agents are equally effective in bonding to enamel and dentin. Several factors negatively influenced bond strength such as bonding RelyX Unicem to enamel without prior phosphoric acid etching; no separate light-curing of a light-polymerizable adhesive prior to cementation, use of a light-polymerizing adhesive converted into a dual-polymerizing adhesive, and use of a dual-cure luting agent with a low auto-polymerizable potential.

Acid Etching, Dental↗

PubMed2006

Development of a self-etch adhesive for resin-modified glass ionomers.

The favorable self-adhesiveness of resin-modified glass ionomers (RMGIs) might be even further improved if the time-consuming and technically sensitive etch-and-rinse pre-treatment step with polyalkenoic acids could be avoided. We undertook this study to assess the effectiveness of an experimental self-etch adhesive for RMGIs that does not need to be rinsed off. Ultrastructural analysis and micro-tensile bond strength testing to enamel and dentin of a RMGI restorative material and a RMGI adhesive were performed after 4 different surface pre-treatments: no conditioning; 25% polyalkenoic acid; an experimental self-etch adhesive; and 37.5% phosphoric acid followed by the experimental self-etch adhesive. The use of an experimental self-etch adhesive increased the bond strength of RMGIs, especially after an additional conditioning step. Interfacial analysis showed the formation of a thin hydroxyapatite-containing hybrid layer. The self-etch technique enhances the user-friendliness of RMGIs and lowers their technique-sensitivity, while maintaining desirable characteristics of the conventional etch-and-rinse approach with polyalkenoic acids.

Acid Etching, Dental↗

PubMed2005

The compound thoracodorsal perforator flap in the treatment of combined soft-tissue defects of sole and dorsum of the foot.

Nine cases of massive soft-tissue loss of the foot were reconstructed by means of a compound (chimera) thoracodorsal artery perforator (TAP) flap, which reconstituted the different functional units (dorsum, heel, instep, weight-bearing surface). In each case, the flap consisted of a skin component isolated on its perforator in combination with a portion of latissimus dorsi muscle and/or serratus fascia, all pedicled on the thoracodorsal vessels. The pedicle length allows up to 4-6 cm of independent mobility of the skin island. The mobility of the various flap components allows the various functional units of the foot to be reconstructed without relying on multiple flaps or anastomoses. The pedicle length was sufficient to be able to perform the anastomosis out of the zone of injury. In some cases the skin island was harvested along with intercostal nerve branches, this gave us the potential to develop a sensate flap. The indications and advantages of this reconstructive method are discussed.

Adolescent↗

PubMed2005

Clinical effectiveness of contemporary adhesives: a systematic review of current clinical trials.

OBJECTIVES: The purpose of this paper was to review current literature on the clinical effectiveness of contemporary adhesives when used to restore cervical non-carious class-V lesions. Restoration retention in function of time was recorded in order to find out if adhesives with a simplified application procedure are as clinically effective as conventional three-step adhesives. DATA SOURCES: Literature published from January 1998 up to May 2004 was reviewed for university-centred clinical trials that tested the clinical effectiveness of adhesives in non-carious class-V lesions. Restoration-retention rates per adhesive reported in peer-reviewed papers as well as IADR-AADR abstracts and ConsEuro abstracts were included and depicted as a function of time in graphs for each of the five adhesive classes (three- and two-step etch-and-rinse adhesives, two- and one-step self-etch adhesives, and glass-ionomers). The guidelines for dentin and enamel adhesive materials advanced by the American Dental Association were used as a reference. Per class, the annual failure rate (%) was calculated. Kruskal-Wallis analysis and Dwass-Steel-Chritchlow-Fligner pairwise comparisons were used to determine statistical differences between the annual failure percentages of the five adhesive categories. RESULTS: Comparison of retention of class-V adhesive restorations as a measure to determine clinical bonding effectiveness of adhesives revealed that glass-ionomers most effectively and durably bond to tooth tissue. Three-step etch-and-rinse adhesives and two-step self-etch adhesives showed a clinically reliable and predictably good clinical performance. The clinical effectiveness of two-step etch-and-rinse adhesives was less favourable, while an inefficient clinical performance was noted for the one-step self-etch adhesives. SIGNIFICANCE: Although there is a tendency towards adhesives with simplified application procedures, simplification so far appears to induce loss of effectiveness. Clinical performance can be correlated with, and predicted by, appropriate types of laboratory study.

Adhesives↗

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↗

PubMed2003

The pyramidalis muscle free flap.

The pyramidalis muscle is introduced as a new small muscle free flap, with description of its anatomy, the surgical technique and the clinical results in five different cases in which this flap was used to treat small recalcitrant wounds in the foot/ankle region. The pyramidalis muscle can be an alternative option in selective cases to reduce donor site morbidity as compared with more traditional free flaps.

Abdominal Muscles↗

PubMed2003

The role of iodine in antisepsis and wound management: a reappraisal.

For more than 150 years, iodine has been used for the prevention of infection and for the treatment of wounds. Nowadays a large amount of published evidence is available and, although it is generally in support of the use of iodine product, it is confused by being a mixture of laboratory, animals and human studies, often using different preparations. This makes interpretation and comparison difficult. After new developments and publications, the role of iodine in antisepsis and in wound management needs to be reevaluated. We mainly focused our review on the following problems: the role of the newly developed formulations of iodine preparations, its antimicrobial activity, the possibility of impairing the wound healing process, the role of iodine in the problem of growing resistance against antibiotics and antiseptics. New formulations seem to keep the same clinical efficacy, avoiding the problem of toxicity; it seems that the antibacterial activity of iodine is superior compared to other products and, in contrast with antibiotics and other antiseptics, it seems to have no resistance problem. It seems that povidone-iodine has all the characteristics to become the first choice antiseptic in wound treatment.

Anti-Infective Agents, Local↗

PubMed2002

A conservative approach for deep dermal burn wounds using polarised-light therapy.

This article reports a clinical study investigating the role of polarised-light therapy in the conservative treatment of deep dermal burn wounds. In 22 out of 67 patients with deep dermal burn wounds, clinical evaluation revealed only a very limited potential for spontaneous healing, and, despite the fact that the majority of the surgeons (four out of six) would have recommended surgery, these patients were treated conservatively with polarised-light therapy (400-2000 nm, 40 m W cm(-2), 2.4 J cm(-2)) until complete closure. Evaluation by a panel of four surgeons, all experts in burn surgery, revealed that conservative treatment of these deep dermal wounds with polarised-light irradiation resulted in a significantly shorter healing time, with almost no hypertrophic scarring, and optimal aesthetic and functional results at long-term follow-up. No extension of the hospital stay was required. Polarised-light therapy may be a valuable way of avoiding surgery in patients with deep dermal burns.

Adolescent↗

PubMed2001

Complete survival of a free flap after early pseudoaneurysm formation and pedicle thrombosis.

A microsurgical pseudoaneurysm is a very rare complication after free flap surgery. The authors report a case of a free thoracodorsal artery perforator flap transferred to a degloving wound on the dorsum of the foot and ankle. The patient developed pedicle thrombosis caused by a septic pseudoaneurysm, which was treated by conservative means. Sufficient vascularization developed within 15 days after surgery and the flap survived completely. This is in sharp contrast to other reported cases of pseudoaneurysm formation, all of which were treated surgically and resulted in flap failure, except in one case. A critical review of the literature is presented and the factors influencing flap survival are discussed.

Aged↗

PubMed2001

The versatility of the pudendal thigh fasciocutaneous flap used as an island flap.

The pudendal thigh flap is a sensate fasciocutaneous flap based on the terminal branches of the superficial perineal artery, which is a continuation of the internal pudendal artery. Several authors have reported using this axial patterned flap in a bilateral fashion to reconstruct the vagina, mostly in patients with vaginal atresia. The technique is simple, safe, and reliable, and no stents or dilators are required. The reconstructed vagina has a natural angle and is sensate. The donor site in the groin can be closed primarily with an inconspicuous scar. The distinct advantages of this flap widen its indications to several other pathologies. In this article, the authors report on the bilateral use of the flap to reconstruct a vagina in patients with congenital atresia (n = 8) and after oncological resection (n = 5). Furthermore, the versatility of this island flap is also demonstrated by its use in a unilateral fashion in patients with recurrent or complex rectovaginal fistulas (n = 4) and in two patients with a defect of the posterior urethra in a heavily scarred perineum. All 31 pudendal thigh flaps survived completely. Some wound dehiscence was observed in two patients. Two other patients required a minor correction at the introitus of the vagina. The functional outcome was excellent in all patients, despite the presence of some hair growth in the flaps. This article discusses the expanding indications of this versatile flap and the refinements in operative technique.

Female↗

PubMed2000

The use of pedicled perforator flaps for reconstruction of lumbosacral defects.

Large lumbosacral defects remain a difficult challenge in reconstructive surgery, especially in the nonparaplegic patient. Traditional options for closure include local rotation or transposition flaps and musculocutaneous flaps. These flaps, however, are not an optimal option in previously irradiated or operated areas, or in cases of large defects. Application of the perforator principle to the traditional musculocutaneous flap creates perforator flaps, which are an additional tool in the treatment of these defects in the nonparaplegic patient. A large amount of healthy, well-vascularized tissue can be transferred on one perforator without sacrificing important underlying muscles. The arc of rotation is also larger than in traditional flaps. The authors present an anatomic overview of three types of pedicled perforator flaps: the superior gluteal artery perforator flap, the lumbar artery perforator flap, and the intercostal artery perforator flap. They also report 4 patients in whom a pedicled perforator flap was used to reconstruct a large lumbosacral defect.

Adult↗

PubMed1999

Sensory nerve repair in perforator flaps for autologous breast reconstruction: sensational or senseless?

The spontaneous return of sensation in autologously reconstructed breasts, especially in the Transverse Rectus Abdominis Myocutaneous (TRAM) flap, generated the belief that sensory reinnervation by nerve repair of the flap would be superfluous. This study compares the sensation of the following non-reconstructed and reconstructed breasts: (1) non-operated breasts; (2) flaps of patients reconstructed with the Deep Inferior Epigastric Perforator (DIEP) flap with sensory nerve repair; (3) flaps of patients reconstructed with the Deep Inferior Epigastric Perforator (DIEP) flap without nerve repair; and (4) flaps of patients reconstructed with the free TRAM flap without nerve repair. Statistically significant lower pressure thresholds were found for DIEP flaps with nerve repair through Semmes-Weinstein testing. More segments of the DIEP flaps with nerve repair reacted to cold, warm and vibratory stimuli compared to flaps without nerve repair. Delayed but satisfactory sensory evoked potential responses were obtained for all reconstructed breasts, but in 46% of TRAM flaps no response could be registered compared with 23% and 0% for DIEP flaps without and with nerve repair, respectively. Questionnaires confirmed the objective data and showed return of erogenous sensation in 30% of the patients with DIEP flaps with nerve repair. Our data reconfirm the possibility of spontaneous return of sensation in pedicled and/or free lower abdominal flaps without nerve repair. Nerve repair in free DIEP flaps nevertheless does restore sensation earlier postoperatively, increases the quality and quantity of sensation in the flap and has a higher chance of providing erogenous sensation. The benefits obtained outweigh the disadvantages of the increased operating time.

Adult↗

PubMed1999

The superior gluteal artery perforator flap: an additional tool in the treatment of sacral pressure sores.

We describe the use of a large skin-subcutaneous tissue flap based on one perforator of the superior gluteal artery (SGA) to reconstruct large midline posterior defects in one stage. The integrity of the gluteus muscles is preserved and we feel this is particularly important in non-paralysed patients. Donor sites were always closed primarily. Use of the superior gluteal artery perforator (SGAP) flap preserves the entire contralateral side as a future donor site. On the ipsilateral side, the gluteal muscle itself is preserved and all flaps based on the inferior gluteal artery are still possible. We recommend this flap in an area where reconstructive possibilities are limited, as it preserves other reconstructive flap options, both on the ipsilateral and contralateral sides.

Adult↗

PubMed1999

Allogeneic cultured keratinocytes vs. cadaveric skin to cover wide-mesh autogenous split-thickness skin grafts.

Improved shock therapy has extended the limits of survival in patients with massive burns, and nowadays skin coverage has become the major problem in burn management. The use of mesh skin grafts is still the simplest technique to expand the amount of available donor skin. However, very wide-mesh skin grafts take a very long time to heal, often resulting in unaesthetic scar formation. On the other hand, allogeneic cultured keratinocytes have been reported as a natural source of growth factors and thus could be useful to improve wound healing of these wide-mesh grafts. A clinical study was performed to compare the use of cryopreserved allogeneic cultured keratinocytes vs. the traditional cadaveric skin as a double layer over widely expanded autogenous skin grafts. This procedure was performed in 18 pairs of full-thickness burn wounds (with similar depth and location) in 11 severely burned patients. Early clinical evaluation was made at 2, 3, and 4 to 5 weeks. Parameters such as epithelialization, granulation tissue formation, infection, and scar formation were evaluated. Biopsies were taken to compare the histological characteristics of the epidermis, the epidermal-dermal junction, and the dermis. Late evaluations were performed at 6 and 12 months regarding color, softness, thickness, and subjective feeling of the scar tissue. Aside from a faster (p < 0.05) epithelialization in the keratinocyte group at 2 weeks, there were no statistically different results in any of the early evaluated parameters, neither clinically nor histologically. At long-term follow-up, clinical results and scar characteristics were not significantly different in the two compared groups. It is concluded from the results of this study that, during the early phase, epithelialization was faster with allogeneic cultured keratinocytes compared with cadaveric skin. However, taking into account the substantial difference in costs, the described use of cryopreserved allogeneic cultured keratinocytes as a double layer on meshed autogenous split-thickness skin grafts can hardly be advocated.

Adolescent↗

PubMed1998

Doppler flowmetry in the planning of perforator flaps.

Perforator flaps have become the first choice in free flap reconstruction of contour defects or skin and fat replacement in our department. The Deep Inferior Epigastric Perforator (DIEP), the Superior Gluteal Artery Perforator (S-GAP) and the Thoracodorsal Artery Perforator (TAP) flaps are now routinely used. By evaluating the vascular anatomy of these flaps preoperatively, we intend to improve our surgical strategy so that these operative procedures can proceed in a faster and safer way. In this study, the results of the colour Duplex scanning in 50 consecutive DIEP flap patients are reviewed and evaluated for their sensitivity and positive predictive value. Also the preoperative information from unidirectional Doppler flowmetry in 30 S-GAP flaps and 11 TAP flaps is evaluated for its reliability. Due to the variable vascular anatomy of the lower abdominal wall and the dorso-lateral thoracic wall we now prefer using the colour Duplex scanning for planning the DIEP and TAP flaps. The more constant course of the branches of the superior gluteal artery allows us to use the easier and cheaper unidirectional Doppler flowmetry for planning the S-GAP flap.

Adult↗

PubMed1998

The antecubital fasciocutaneous island flap for elbow coverage.

Soft-tissue defects in the area of the periolecranon may be a source of concern to the reconstructive surgeon who aims for durable protection with a minimum of drawbacks. Lamberty and Cormack described the antecubital fasciocutaneous flap both as a local transposition and as a free flap. The island version of this flap enables a single-stage transfer of thin, pliable, sensitive skin into the region of the periolecranon without further scarring around the defect. In general, most of the donor site can be closed primarily together with a small, full-sheet, split-thickness skin graft on the remaining skin defect on the volar surface of the distal forearm. An additional advantage of this flap is the rather straightforward dissection with minimal repercussion on the forearm contour. An anatomic overview as well as 4 patients are described to illustrate the appealing features of this fasciocutaneous flap.

Adult↗