Denervation of the thumb carpometacarpal joint for symptomatic osteoarthritis in 46 patients.

We investigated the effect of an extended denervation procedure in the thumb carpometacarpal (CMC) joint in patients suffering from CMC osteoarthritis. Between 2006 and 2018, 46 patients underwent the procedure in our clinic and were included in this retrospective study. Pain, strength, range of motion, DASH score, complications and overall satisfaction were determined. Assessment showed a significant decrease in pain and excellent physical function at a median 5 years' follow-up. Twelve patients needed secondary surgery due to persistent pain. Overall, 28 of the 46 patients were satisfied with the results of the denervation. Even though the results of CMC denervation are poorer than with simple trapeziectomy, considerable pain relief can be achieved in selected young, physically active patients by exclusively soft-tissue surgery, conserving the biomechanical properties of the joint. In case of failure of the procedure, all other options remain available.

The adipofasciocutaneous gluteal fold perforator flap a versatile alternative choice for covering perineal defects.

AIM: Perineal defects following the resection of anorectal malignancies are a reconstructive challenge. Flaps based on the rectus abdominis muscle have several drawbacks. Regional perforator flaps may be a suitable alternative. We present our experience of using the gluteal fold flap (GFF) for reconstructing perineal and pelvic defects. METHODS: We used a retrospective chart review and follow-up examinations focusing on epidemiological, oncological (procedure and outcome), and therapy-related data. This included postoperative complications and their management, length of hospital stay, and time to heal. RESULTS: Twenty-two GFFs (unilateral n = 8; bilateral n = 7) were performed in 15 patients (nine women and six men; anal squamous cell carcinoma n = 8; rectal adenocarcinoma n = 7; mean age 65.5 + 8.2 years) with a mean follow-up time of 1 year. Of the cases, 73.3% were a recurrent disease. Microscopic tumor resection was achieved in all but one case (93.3%). Seven cases had no complications (46.7%). Surgical complications were classified according to the Clavien-Dindo system (grades I n = 2; II n = 2; IIIb n = 4). These were mainly wound healing disorders that did not affect mobilization or discharge. The time to discharge was 22 + 9.9 days. The oncological outcomes were as follows: 53.3% of the patients had no evidence of disease, 20% had metastatic disease, 20% had local recurrent disease, and one patient (6.7%) died of other causes. CONCLUSIONS: The GFF is a robust, reliable flap suitable for perineal and pelvic reconstruction. It can be raised quickly and easily, has an acceptable complication rate and donor site morbidity, and does not affect the abdominal wall.

Randomized in situ study on the efficacy of CO2 laser irradiation in increasing enamel erosion resistance.

OBJECTIVES: The aim of this double-blind, randomized in situ study was to evaluate the erosion-preventive effect of a specific set of CO2 laser parameters, associated or not with fluoride. METHODS: Two hundred forty bovine enamel blocks were prepared for individual palatal appliances (n = 6 samples/appliance). The study had four phases of 5 days each, with ten volunteers and the following treatments: CO2 laser irradiation (L), fluoride treatment (F), combined fluoride and laser treatment (FL), and no treatment, control (C). Laser irradiation was performed at 0.3 J/cm2 (5 µs/226 Hz/10.6 µm) and the fluoride gel contained AmF/NaF (12'500 ppm F-/pH = 4.8-6). For erosive demineralization, the appliances were immersed extra-orally in citric acid (0.05 M/20 min/pH = 2.3) twice daily. Analysis of enamel surface loss was done using a 3D-laser profilometer on 3 days. Additionally, fluoride uptake was quantified and scanning electron microscopies were done. Data were analyzed with repeated measures ANOVA and post hoc pairwise comparisons (α = 0.05). RESULTS: At all analyzing days, both laser groups caused the lowest means of enamel loss, which were also statistically significant lower than C (p < 0.05). At day 5, FL means ± SD (33.6 ± 12.6 µm) were even significantly lower than all other groups (C 67.8 ± 15.4 µm; F 57.5 ± 20.3 µm; L 46.8 ± 14.5 µm). Significantly increased enamel fluoride uptake was observed for both fluoride-containing groups (p < 0.05) at day 1. CONCLUSION: Compared to the control, the CO2 laser irradiation with a specific set of laser parameters (0.3 J/cm2/5 µs/226 Hz) either alone or in combination with a fluoride gel (AmF/NaF) could significantly decrease enamel erosive loss up to 5 days in situ. CLINICAL RELEVANCE: Combined CO2 laser-fluoride treatment has a significant anti-erosive effect.

Increased differentiation and production of extracellular matrix components of primary human osteoblasts after cocultivation with endothelial cells: A quantitative proteomics approach.

Coculturing of bone-forming and blood vessel-forming cells is a strategy aimed at increasing vascularity of implanted bone constructs in tissue-engineering applications. We previously described that the coculture of primary human osteoblasts (hOBs) and human umbilical vein endothelial cells (HUVECs) improves the differentiation of both cell types, leading to the formation of functional blood vessels and enhanced bone regeneration. The objective of this study was to further delineate the multifaceted interactions between both cell types. To investigate the proteome of hOBs after cocultivation with HUVECs we used stable isotope labeling by amino acids in cell culture, revealing 49 significantly upregulated, and 54 significantly downregulated proteins. Amongst the highest regulated proteins, we found the proteins important for osteoblast differentiation, cellular adhesion, and extracellular matrix function, notably: connective tissue growth factor, desmoplakin, galectin-3, and cyclin-dependent kinase 6. The findings were confirmed by enzyme-linked immunosorbent assays. We also investigated whether the mRNA transcripts correlate with the changes in protein levels by quantitative real-time reverse transcription polymerase chain reaction. In addition, the data was compared to our previous microarray analysis of hOB transcriptome. Taken together, this in-depth analysis delivers reliable data suggesting the importance of coculturing of hOBs and HUVECs in tissue engineering.

[Current Perceptions of Lipofilling on the Basis of the New Guideline on "Autologous Fat Grafting"]. / Aktuelle Erkenntnisse zur Eigenfett Transplantation anhand der neuen Leitlinie "Autologe Fetttransplantation".

Introduction: Autologous fat transfer has recently become an increasingly popular surgical procedure and comprises harvesting, processing and transplantation of adipose tissue, as well as professional follow-up care. This method, as a surgical procedure, can be utilised for trauma-, disease- or age-related soft tissue volume deficits and soft tissue augmentation. As usage is increasing, but the variables of fat harvest, specific indications and fashion of fat transfer are poorly defined, there is a great demand for development of a guideline in the field of reconstructive and aesthetic surgery. Methods: All relevant points were discussed within the scope of a consensus conference including a nominal group process of all societies involved in the procedure and ratified with a strong consensus (>95%). Literature from the standard medical databases over the last 10 years was retrieved, studied and specific guidelines were concluded. Results: Consensus was achieved among all professionals involved on the following points: 1. definition 2. indication/contraindication, 3. preoperative measures 4. donor sites 5. techniques of processing 6. transplantation 7. follow-up care 8. storage 9. efficacy 10. documentation 11. evaluation of patient safety. Conclusion: Definite indications and professional expertise are paramount for autologous fat tissue transfer. Successful transfers are based on the use of correct methods as well as specific instruments and materials. Autologous adipose tissue transplantation is considered to be a safe procedure in reconstructive and aesthetic surgery, due to the low rate of postoperative complications and sequelae.

[Comparison of the Results of Lundborg's and Sirotakova's Resection-Suspension Arthroplasty for the Treatment of Trapeziometacarpal Joint Osteoarthritis]. / Vergleich der Ergebnisse der Resektions-Suspensionsarthroplastik nach Lundborg und Sirotakova zur Behandlung der Rhizarthrose.

BACKGROUND AND AIMS: The aim of this prospective randomised study was to compare Sirotakova's and Lundborg's methods of resection-suspension arthroplasty using the abductor pollicis longus tendon in the surgical treatment of osteoarthritis of the trapeziometacarpal joint. PATIENTS AND METHODS: Between 2009 and 2012, 38 patients (29 female, 9 male) with symptomatic trapeziometacarpal osteoarthritis (34% stage II, 58% stage III and 8% stage IV according to the Eaton-Littler classification) were randomly allocated to one of the surgical methods (mean age 62.7 years, range 43-85). Preoperatively, the following data were collected: pain intensity (Visual Analogue Scale, VAS; at rest: Lundborg 4.4±1.7; Sirotakova 4.6±2.1), strength (key pinch force Lundborg 8.1 kPa±6.6; Sirotakova 10.4 kPa±10.8), range of motion in the trapeziometacarpal joint (Lundborg 61.64±26.4; Sirotakova 46.67±25.6), Kapandji index (Lundborg 9.42±1.4; Sirotakova 9.33±1.5), distance between the base of the first metacarpal bone and the scaphoid bone as measured by standardised x-ray images (Lundborg 12 mm±1.5; Sirotakova 11.4 mm±3), DASH questionnaire (Lundborg 40.4±13.9; Sirotakova 49.9±23.5). A significant difference between the 2 groups was not found. Patients were examined 3 and 9 months postoperatively. RESULTS: Both resection-suspension arthroplasty procedures led to a statistically significant postoperative reduction of pain, a significant improvement in radial and palmar abduction, a significant gain in quality of life and significant asymptomatic proximalisation of the first metacarpal bone. There was no significant difference in postoperative strength. CONCLUSION: Both methods lead to reliable and satisfying results. Given our findings we cannot generally recommend one method over the other.

Overexpression of Hif-1α in Mesenchymal Stem Cells Affects Cell-Autonomous Angiogenic and Osteogenic Parameters.

Reconstruction of large bone defects still represents a major medical challenge. In recent years tissue engineering has developed techniques based on adult mesenchymal stem cells (MSCs) that could represent an attractive therapeutical option to treat large bone defects in the future. It has been demonstrated in various animal models that ex vivo expanded MSCs are capable of promoting the regeneration of skeletal defects after implantation. However, for the efficient regeneration of bone in tissue engineering applications, a rapid vascularization of implanted grafts is essential to ensure the survival of cells in the early post-implantational phase. A promising strategy to enhance vascularization of MSC-containing implants could consist of overexpression of the angiogenic master transcription factor Hypoxia-inducible factor 1 (Hif-1) in the MSCs in order to induce angiogenesis and support osteogenesis. In the present study, we overexpressed Hif-1α in MSCs by using recombinant adenoviruses and investigated cell-autonomous effects. Overexpression of Hif-1α enhanced proliferation, migration, cell survival and expression of pro-angiogenic genes. Other parameters such as expression of the osteogenic markers BMP-2 and RunX2 were decreased. Hif-1α overexpression had no effect on invasion, senescence and osteogenic differentiation of MSCs. Our experiments revealed multifarious effects of Hif-1α overexpression on cell-autonomous parameters. Therefore, Hif-1α overexpression may represent a therapeutic option to improve cellular functions of MSCs to treat critical sized bone defects.

[Application possibilities and initial experience with digital volume tomography in hand and wrist imaging]. / Digitale Volumentomografie (DVT) des knöchernen Handskeletts: Erste Erfahrungen und Anwendungsmöglichkeiten.

During the last decade, DVT (digital volume tomography) imaging has become a widely used standard technique in head and neck imaging. Lower radiation exposure compared to conventional computed tomography (MDCT) has been described. Recently, DVT has been developed as an extremity scanner and as such represents a new imaging technique for hand surgery. We here describe the first 24 months experience with this new imaging modality in hand and wrist imaging by presenting representative cases and by describing the technical background. Furthermore, the method's advantages and disadvantages are discussed with reference to the given literature.

[Motor replacement surgery via tendon transfer in radial nerve palsy]. / Motorische Ersatzplastik durch Sehnentransposition bei Lähmung des Nervus radialis.

OBJECTIVE: Restoration of active extension of wrist, thumb and digits by muscle-tendon transposition. INDICATIONS: Radial nerve palsy due to peripheral nerve injury. Peripheral nerve disease. Muscle or tendon injury. Restoration of wrist extension in high radial nerve palsy. CONTRAINDICATIONS: Reversible distal radial nerve palsy, absence of suitable donor muscles, spasticity, limited range of motion of affected joints, extensive scarring and inappropriate soft tissue conditions, unjustifiable loss of function at donor site. Reinnervated donor muscles, progressive muscle disease, insufficient patient compliance. SURGICAL TECHNIQUE: Dissection of the flexor carpi ulnaris, palmaris longus and pronator teres tendon insertion. Transposition of the tendons. Interweaving of tendons of the pronator teres and extensor carpi radialis brevis muscles, the extensor digitorum communis and flexor carpi ulnaris muscles, as well as the extensor pollicis longus and palmaris longus muscles using the Pulvertaft technique. POSTOPERATIVE MANAGEMENT: 3 Weeks immobilization in forearm splint. Additional immobilization for 2 weeks at night. Subsequently, intensive physical and occupational therapy for another 4-6 weeks is required, starting 3 weeks postoperatively. RESULTS: The procedure was carried out in 12 patients over the past 14 years. We treated proximal radial nerve palsy in nine cases. In accordance with the current medical literature, we consider the described motor replacement surgery a reliable procedure.

Cytogenetic aspects of childhood leukemias.

Recurrent non-random chromosome abnormalities, including numerical or structural changes such as translocations, inversions, insertions or deletions within the leukemia cell nucleus, have been discovered in approximately 80% of patients with a malignant hematological disease. These reciprocal translocations correlate with specific cellular subtypes of hematopoeisis at the stage of their maturation arrest and are therefore important for diagnosis. Some of these aberrations are independent prognostic indicators and help to stratify patients into different risk-adapted therapy groups. Owing to new laboratory methods such as the fluorescence in situ hybridization (FISH) and modified polymerase chain reaction (RT-PCR) the chromosomal breakpoints can be investigated and the rearrangements of genes which produce the abnormal proteins can be identified. Due to the high sensitivity of these available data a new prognostic factor, the "minimal residual disease" (MRD), can be investigated at diagnosis and at intervals during the treatment period. Since we now know which oncoproteins are involved, a target-directed therapy with inhibitors might be possible in the future.Standard cytogenetic and molecular genetic analysis of the leukemia karyotype is of the utmost importance for classification (WHO), therapy and therapy results in the acute childhood leukemias.

Increased extracellular matrix and proangiogenic factor transcription in endothelial cells after cocultivation with primary human osteoblasts.

The most promising strategies in bone engineering have concentrated on providing sufficient vascularization to support the newly forming tissue. In this context, recent research in the field has focused on studying the complex interactions between bone forming and endothelial cells. Our previous work has demonstrated that direct contact cocultivation of human umbilical vein endothelial cells (HUVECs) with primary human osteoblasts (hOBs) induces the osteogenic phenotype and survival of hOBs. In order to investigate the mechanisms that lead to this effect, we performed microarray gene expression profiling on HUVECs following cocultivation with hOBs. Our data reveal profound transcriptomic changes that are dependent on direct cell contact between these cell populations. Pathway analysis using the MetaCore™ platform and literature research suggested a striking upregulation of transcripts related to extracellular matrix and cell-matrix interactions. Upregulation of a number of major angiogenetic factors confirms previous observations that HUVECs enter a proangiogenic state upon cocultivation with osteoblasts. Interestingly, the downregulated transcripts clustered predominantly around cell cycle-related processes. The microarray data were confirmed by quantitative real-time RT-PCR on selected genes. Taken together, this study provides a platform for further inquiries in complex interactions between endothelial cells and osteoblasts.

Refinements in reconstruction of penile skin loss using intra-operative prostaglandin injections, postoperative tadalafil application and negative pressure dressings.

PURPOSE: Penile shaft skin defects represent demanding reconstructive tasks because a high degree of flexibility and stability of the skin grafts are essential to allow regular erections and sexual intercourse. METHODS: A new concept of tailoring skin grafts to the erect penis by intra-operative application of prostaglandin E1 and postoperative stabilisation by negative-pressure wound therapy and pharmacological expansion by tadalafil was tested on four patients with penile shaft skin defects. Graft take, stability, pliability, softness and aesthetic results were evaluated up to at least 12 months postoperatively. The ratio of the skin transplanted area in the non-erect compared to the erect penis (non-erect/erect ratio) and the ratio of the skin transplanted area in the erect penis at 12 months compared to intra-operatively (Post/Pre ratio) was determined to define the amount of graft contraction and flexibility. International Index of Erectile Function (IIEF)-5 scores were evaluated postoperatively. RESULTS: There were no complications. Graft take was 97, 100, 100 and 100%. Stable skin grafts were achieved after 2 weeks. Sexual intercourse was possible at 2-3 months. The Post/Pre ratio was between 81 and 87% and proves comparably mild contracture rates. The non-erect/erect ratio of 50-72% shows how significantly undersized penile shaft skin grafts are when adjusted to the non-erect penis and that an adequate flexibility for erections can be reconstructed. IIEF-5 scores proved regular potency in three patients; one patient was no longer sexually active. CONCLUSIONS: With the new concept of tailoring the skin graft to the erect penis, pharmacological expansion and external stabilisation by vacuum-assisted closure (VAC) dressing the difficult task of penile skin reconstruction can be facilitated, accelerated and the functional and aesthetic outcome improved compared to earlier efforts or to results presented in the literature.

[Soft tissue reconstruction with a temporoparietal fascial flap (TPFF)]. / Der temporoparietale Faszienlappen zur Rekonstruktion von Weichteildefekten.

OBJECTIVE: Soft tissue reconstruction with a temporoparietal fascial flap (TPFF). INDICATIONS: Defect coverage with thin, pliable, and well-vascularized tissue. A bilayered TPFF provides a gliding surface in tendon reconstruction. Further options include TPFF harvest with overlying skin or subjacent bone for composite tissue reconstruction or the application as a sensate local fascial flap. Maximum defect dimensions: 17 × 14 cm. CONTRAINDICATIONS: Absolute: prior injury to the flap or flap pedicle, temporal arteritis, Moyamoya syndrome, defects with volume deficit. Relative: alopecia along the planned incision. SURGICAL TECHNIQUE: Pedicle location is outlined using Doppler ultrasound. Injection of the incision line with diluted epinephrine solution. Skin incision with subsequent visualization of the temporoparietal fascia and supplying vessels. Skin flaps are raised carefully paying special attention to the hair follicles (CAVE: postoperative alopecia). Primary closure of the donor site. Defect coverage with pedicled or free TPFF with subsequent full or split-thickness skin grafting. Dressing: Bolster or V.A.C. POSTOPERATIVE MANAGEMENT: Immobilization/elevation in the setting of extremity reconstruction. Removal of bolster dressing or V.A.C. on postoperative day 5. Dangling protocol instituted on postoperative day 7. Removal of sutures/staples at the donor site on postoperative day 5-7 and at the recipient site on postoperative day 12-14. RESULTS: The TPFF was utilized for soft tissue reconstruction in 8 patients. A pedicled TPFF was used in 2 patients. Mean time to healing was 16.3 days. Mean follow-up was 13.4 months. Successful reconstructive results with satisfactory functional and aesthetic appearance were obtained in all patients. Complications were encountered in 3 patients and included alopecia at the donor site and iatrogenic injury to the frontal branch of the facial nerve. Vascular compromise was observed in the early postoperative period in a third patient. However, operative revision resulted in successful flap salvage.

The "PIP scandal" - Complications in Breast Implants of Inferior Quality: State of Knowledge, Official Recommendations and Case Report.

Following the clinical observation of high rate of ruptures of breast implants of the French manufacturer Poly Implant Prothèse (PIP), the French Health Products Safety Agency (Afssaps) removed these products from the market in March 2010. Physical and toxicological tests confirmed the use of silicone of improper quality both for the shell and the gel filling. Until now (12/2011), no acute toxicity or mutagenicity could be observed, but 20 cases of malignancies occured in carriers of PIP-prostheses. By means of a clinical example, we summarize the official recommendations of the Afssaps and its German equivalent, the Bundesinstitut für Arzneimittel und Medizinprodukte (BfArM) for diagnosis and treatment in women with PIP breast implants. Furthermore, we intend to raise awareness for the fact that the German GfE Medizintechnik and the Dutch manufacturer Rofil distributed the identical product with a different label. Supplementary, the medical and medico-legal aspects of the "PIP scandal" are discussed.

T-RFLP-based differences in oral microbial communities as risk factor for development of oral diseases under stress.

The human oral microbiome is comprised of approximately 800 different bacterial species many of which are as yet uncultivated. Their dynamics and variability in relation to health and disease are still poorly understood. Here we tested the hypothesis that the emergence of stress-induced periodontal diseases is predictable based on the composition of the initial microbiota. As a model, we analysed 58 individuals performing a challenging expedition (exposure to various stress-factors due to changes in diet, hygiene, temperature, physical and mental stress) in remote regions of the Himalayans (Annapurna Himal). Plaque samples were taken at start (Bhulbule) and destination (3000 meter difference in altitude) seven days later (Manang). Twenty-eight individuals remained symptom-free (Group I) while 30 participants developed periodontal problems, mostly gingivitis (Group II). The microbiota was monitored via T-RFLP-analysis of amplified 16S rRNA genes directly from the plaque samples. Based on the Additive-Main-Effects-Multiplicative-Interactions-model (AMMI) using the T-Rex software variation from T-RF main effects was at least 95%, indicating that most variation was due to inherent differences in microbial communities among individuals. However, an interaction signal up to 3% was consistently observed between groups I and II but not between the two time points of sampling regardless of selected analytical parameters. The data, supported by heterogeneity, diversity and similarity indices indicated marked differences between groups I and II already prior the onset of clinical symptoms. These differences may provide the basis for using ecological parameters of oral microbial communities as early diagnostic marker for the onset of oral disorders and infections.

Prevention of toothbrushing abrasion of acid-softened enamel by CO(2) laser irradiation.

OBJECTIVE: The aim of the present study was to evaluate the effect of CO(2) laser irradiation (10.6µm) at 0.3J/cm(2) (0.5µs; 226Hz) on the resistance of softened enamel to toothbrushing abrasion, in vitro. METHODS: Sixty human enamel samples were obtained, polished with silicon carbide papers and randomly divided into five groups (n=12), receiving 5 different surface treatments: laser irradiation (L), fluoride (AmF/NaF gel) application (F), laser prior to fluoride (LF), fluoride prior to laser (FL), non-treated control (C). After surface treatment they were submitted to a 25-day erosive-abrasive cycle in 100ml sprite light (90s) and brushed twice daily with an electric toothbrush. Between the demineralization periods samples were immersed in supersaturated mineral solution. At the end of the experiments enamel surface loss was determined using a contact profilometer and morphological analysis was performed using scanning electron microscopy (SEM). For SEM analysis of demineralization pattern, cross-sectional cuts of cycled samples were prepared. The data were statistically analysed by one-way ANOVA model with subsequent pairwise comparison of treatments. RESULTS: Abrasive surface loss was significantly lower in all laser groups compared to both control and fluoride groups (p<0.0001 in all cases). Amongst the laser groups no significant difference was observed. Softened enamel layer underneath lesions was less pronounced in laser-irradiated samples. CONCLUSION: Irradiation of dental enamel with a CO(2) laser at 0.3J/cm(2) (5µs, 226Hz) either alone or in combination with amine fluoride gel significantly decreases toothbrushing abrasion of softened-enamel, in vitro.

Rehardening of acid-softened enamel and prevention of enamel softening through CO2 laser irradiation.

OBJECTIVES: The aims of the present study were to investigate whether irradiation with a CO(2) laser could prevent surface softening (i) in sound and (ii) in already softened enamel in vitro. METHODS: 130 human enamel samples were obtained and polished with silicon carbide papers. They were divided into 10 groups (n = 13) receiving 5 different surface treatments: laser irradiation (L), fluoride (AmF/NaF gel) application (F), laser prior to fluoride (LF), fluoride prior to laser (FL), non-treated control (C); and submitted to 2 different procedures: half of the groups was acid-softened before surface treatment and the other half after. Immersion in 1% citric acid was the acid challenge. Surface microhardness (SMH) was measured at baseline, after softening and after treatment. Additionally, fluoride uptake in the enamel was quantified. The data were statistically analysed by two-way repeated measurements ANOVA and post hoc comparisons at 5% significance level. RESULTS: When softening was performed either before or after laser treatment, the L group presented at the end of the experiments SMH means that were not significantly different from baseline (p = 0.8432, p = 0.4620). Treatment after softening resulted for all laser groups in statistically significant increase in SMH means as compared to values after softening (p < 0.0001). Enamel fluoride uptake was significantly higher for combined laser-fluoride treatment than in control (p<0.0001). CONCLUSION: Irradiation of dental enamel with a CO(2) laser at 0.3J/cm(2) (5 µs, 226 Hz) not only significantly decreased erosive mineral loss (97%) but also rehardened previously softened enamel in vitro.

Dentine caries inhibition through CO(2) laser (10.6µm) irradiation and fluoride application, in vitro.

OBJECTIVE: The purpose of the study was to investigate whether dentine irradiation with a pulsed CO(2) laser (10.6µm) emitting pulses of 10 ms is capable of reducing dentine calcium and phosphorus losses in an artificial caries model. DESIGN: The 90 dentine slabs obtained from bovine teeth were randomly divided into six groups (n=15): negative control group (GC); positive control group, treated with fluoride 1.23% (GF); and laser groups irradiated with 8 J/cm(2) (L8); irradiated as in L8+fluoride 1.23% (L8F); irradiated with 11 J/cm(2) (L11); irradiated as in L11+fluoride 1.23% (L11F). After laser irradiation the samples were submitted to a pH-cycling model for 9 days. The calcium and phosphorous contents in the de- and remineralization solutions were measured by means of inductively coupled plasma optical emission spectrometer--ICP-OES. Additionally intrapulpal temperature measurements were performed. The obtained data were analysed by means of ANOVA and Tukey's test (α=0.05). RESULTS: In the demineralization solutions the groups L11F and GF presented significantly lower means of calcium and phosphorous losses than the control group; and in L11F means were significantly lower than in the fluoride group. Both irradiation parameters tested caused intrapulpal temperature increase below 2°C. CONCLUSION: It can be concluded that under the conditions of this study, CO(2) laser irradiation (10.6 µm) with 11 J/cm(2) (540 mJ and 10 Hz) of fluoride treated dentine surfaces decreases the loss of calcium and phosphorous in the demineralization process and does not cause excessive temperature increase inside the pulp chamber.

CO2 Laser (10.6 microm) parameters for caries prevention in dental enamel.

Although CO(2) laser irradiation can decrease enamel demineralisation, it has still not been clarified which laser wavelength and which irradiation conditions represent the optimum parameters for application as preventive treatment. The aim of the present explorative study was to find low-fluence CO(2) laser (lambda = 10.6 microm) parameters resulting in a maximum caries-preventive effect with the least thermal damage. Different laser parameters were systematically evaluated in 3 steps. In the first experiment, 5 fluences of 0.1, 0.3, 0.4, 0.5 and 0.6 J/cm(2), combined with high repetition rates and 10 micros pulse duration, were chosen for the experiments. In a second experiment, the influence of different pulse durations (5, 10, 20, 30 and 50 micros) on the demineralisation of dental enamel was assessed. Finally, 3 different irradiation times (2, 5 and 9 s) were tested in a third experiment. In total, 276 bovine enamel blocks were used for the experiments. An 8-day pH-cycling regime was performed after the laser treatment. Demineralisation was assessed by lesion depth measurements with a polarised light microscope, and morphological changes were assessed with a scanning electron microscope. Irradiation with 0.3 J/cm(2), 5 micros, 226 Hz for 9 s (2,036 overlapping pulses) increased caries resistance by up to 81% compared to the control and was even significantly better than fluoride application (25%, p < 0.0001). Scanning electron microscopy examination did not reveal any obvious damage caused by the laser irradiation.