Olivier Laboux

Current state of the art of biphasic calcium phosphate bioceramics

We have developed 15 years ago, with the collaboration of Lynch, Nery, and LeGeros in the USA, a bioactive concept based on biphasic calcium phosphate (BCP) ceramics. The concept is determined by an optimum balance of the more stable phase of HA and more soluble TCP. The material is soluble and gradually dissolves in the body, seeding new bone formation as it releases calcium and phosphate ions into the biological medium. The bioactive concept based on the dissolution/transformation processes of HA and TCP has been applied to both Bulk, Coating and Injectable Biomaterials. The events at the calcium phosphate (CaP) biomaterial/bone interface represent a dynamic process, including physico-chemical processes, crystal/proteins interactions, cells and tissue colonization, bone remodeling, finally contributing to the unique strength of such interfaces. An important literature and numerous techniques have been used for the evaluation of the fundamental physico chemical and biological performance of BCP concept. This type of artificial bone used from a long time in preclinical and in clinical trial, revealed the efficiency for bone filling, performance for bone reconstruction and efficacy for bone ingrowth at the expense of the micro macroporous BCP bioceramics.

Bioactive materials in endodontics.

Endodontic treatment in dentistry is a delicate procedure and many treatment attempts fail. Despite constant development of new root canal filling techniques, the clinician is confronted with both a complex root canal system and the use of filling materials that are harmful for periapical tissues. This paper evaluates reported studies on biomaterials used in endodontics, including calcium hydroxide, mineral trioxide aggregate, calcium phosphate ceramics and calcium phosphate cements. Special emphasis is made on promising new biomaterials, such as injectable bone substitute and injectable calcium phosphate cements. These materials, which combine biocompatibility, bioactivity and rheological properties, could be good alternatives in endodontics as root canal fillers. They could also be used as drug-delivery vehicles (e.g., for antibiotics and growth factors) or as scaffolds in pulp tissue engineering.

Study of the maturation of the organic (type I collagen) and mineral (nonstoichiometric apatite) constituents of a calcified tissue (dentin) as a function of location: a Fourier transform infrared microspectroscopic investigation.

Fourier transform infrared microspectroscopy (FTIRM) was used to investigate the organic and mineral phases of a calcified tissue (dentin) as a function of its location from predentin toward enamel. Thin dentin slices (decalcified or not) were fixed in formaldehyde and embedded in glycolmethylmethacrylate (GMA). Fixation did not denature collagen, and GMA did not interact with organic or mineral constituents of dentin. The ν1ν3 PO4 domain was studied in particular in order to estimate mineral maturity and amide I, II, A, and B to obtain data on protein conformation. The results showed that dentin apatite became increasingly mature (stoichiometric) from the mineralization front toward the enamel, especially through loss of HPO42− groups and vacancies. Moreover, collagen fibrils became less and less hydrated, suggesting that intrafibrillar mineralization partially dehydrated the collagen. Combined study of the organic and mineral fractions of calcified tissues may help clarify their relationships in physiological and pathological tissues.

Outcome and perspectives in bioactive coatings: What's new, what's coming

Abstract The main interest of calcium phosphate (CaP) coating is osteoconduction and faster and better osteogenic cells spreading and bone ingrowth onto the dental or orthopaedic surface implant. CaP coating are bioactive materials that have been shown to promote early bone apposition at the surface of metallic implants. However, every CaP is more or less resorbable; in this way, new technologies are developed to promote and/or induce osteogenic activity. These evolutions tend to control the chemical nature of CaP ceramic, the porosity and the thickness of the coating; and/or to integrate in the coating osteoinductive or therapeutic agents (biphosphonates, antibiotics); and/or to immobilize constitutional elements of bone on implants surface (growth factors (BMP, TGF-β), adhesion proteins (collagen, fibronectin, laminin, vitronectin) or peptides (RGD sequence). All these technological and biologic progress should be evaluated compared to possible side effects and the long-term benefit for the patients.

Quantitative Immunogold Labeling of Bone Sialoprotein and Osteopontin in Methylmethacrylate-embedded Rat Bone

Methylmethacrylate (MMA) embedding of undecalcified bone is routinely employed for histomorphometric analyses. Although MMA-embedded bone has been used for immunolabeling at the light microscopic level after removal of the resin, there are no such reports for electron microscopy. The aim of the present study was to determine whether MMA embedding can be used for ultrastructural immunolabeling and how it compares to LR White (LRW), an acrylic resin frequently used for immunocytochemistry of bone. Rat tibiae were fixed by vascular perfusion with aldehyde and embedded either in MMA or LRW resin. Thin sections were processed for postembedding protein A-gold immunolabeling with antibodies to rat bone sialoprotein (BSP) and osteopontin (OPN). The density of gold particles over bone was quantified. The density and distribution of immunolabeling for BSP and OPN respectively, were comparable between MMA and LRW. These results indicate that MMA performs as well as LRW for the ultrastructural immunolabeling of noncollagenous bone matrix proteins.

Tooth desensitization with an Er:YAG laser: in vitro microscopical observation and a case report

Tooth hypersensitivity is a frequent condition that causes discomfort and sometimes severe pain. It is caused by exposure of spots of dentinal tubules to the oral environment. Conventional desensitizing agents (professional pastes, toothpastes, mouthwashes) aim to obliterate the exposed dentinal tubules. Laser desensitization was introduced as an alternative efficient tool for the immediate treatment of tooth hypersensitivity. We explored in vitro the microscopical occluding effects of the Er:YAG laser on exposed dentinal tubules. The clinical application of this technique is also described.

A recall program for the outcome of conventional root canal treatment performed in a teaching hospital

Abstract Objectives: This study investigated the long-term survival and the prognostic factors of endodontic treatments performed in a dental teaching hospital. The aim was to calculate the probabilities of success or failure according to the follow-up extent and to assess the time allowed for a complete periapical healing. Materials and methods. A cohort of 185 teeth were re-examined 1–4 years after treatment. The outcome was assessed on the basis of radiographic and clinical criteria as success, uncertain or failure. A survival analysis using the Cox model was used (i) to explore tooth survival and periapical healing over the time and (ii) to highlight the predictive factors of treatment outcome. Results. After 2 years, the appearance of an apical periodontitis remained lower than 3.5%, whereas only 22.8% of periapical healed cases were notified. The prognosis factors are: (i) for teeth with initial healthy periapical conditions, coronal leakage (p = 0.002) with the higher risk of failure (RR = 19.77), absence of correspondence filling length/shaping = 0.026), type of teeth (p = 0.041) and (ii) for teeth with apical periodontitis, number of root canals (p = 0.000,91), correspondence filling length/shaping length (p = 0.017) and over-filling (p = 0.09). New periapical lesions or tooth loss were recorded after 2 years. Half of the successful cases of periapical healing were observed during the follow-up from 2–4 years. Conclusions. This longitudinal study shows that coronal leakage is responsible for late failure and that periapical healing is long to achieve. Therefore, endodontic treatments may require a follow-up of over 2 years.

Clinical Outcomes After Nonsurgical Periodontal Therapy with an Er:YAG Laser Device: A Randomized Controlled Pilot Study

OBJECTIVE The purpose of this study was to compare the short-term effects of nonsurgical periodontal treatment with the short-term effects of Er:YAG laser debridement (ERL) and manual scaling and root planning (SRP) in nonsmoking patients with chronic periodontitis. METHODS Nineteen nonsmoking patients (mean age 60.7) with chronic generalized periodontitis were randomly treated with ERL or SRP in a split-mouth design. Clinical attachment level (CAL), periodontal pocket depth (PPD), and bleeding on probing (BOP) were recorded. Immediately after completion of the treatment procedure, patients used a visual analogue scale (VAS) to grade the degree of discomfort experienced during treatment. RESULTS Both groups showed significant reductions in their PPD, CAL, and BOP values 2 months after treatment. The sites treated with Er:YAG laser demonstrated mean PPD changes that varied from 5.00 ± 0.63 to 3.54 ± 0.83 mm, mean CAL changes that varied from 5.19 ± 0.69 to 3.86 ± 0.94 mm, and BOP changes that varied from 26.57 ± 12.54 to 13.17 ± 7.52 mm. Sites treated with manual SRP demonstrated mean PPD changes that varied from 4.91 ± 0.55 to 3.51 ± 0.98 mm, mean CAL changes that varied from 5.08 ± 0.59 to 3.95 ± 1.16 mm, and BOP values that varied from 24.81 ± 7.65 to 15.41 ± 6.32 mm. Comparison of the two techniques demonstrated the statistically significant superiority of Er:YAG only for the CAL scores (p<0.05). CONCLUSIONS Within the limits of this study, ERL may be posited as an alternative to mechanical treatment in the management of chronic periodontitis. In addition, ERL may be performed on patients who are sensitive to the use of injectable anesthetics. Future studies, with larger samples, are needed to determine the long-term clinical outcomes of ERL.

Proteins of the mineral compartment of bovine fetal enamel share common antigenic determinants with serum proteins

SummaryTwo fractions were separated from the proteins of the mineral compartment of bovine developing enamel on the basis of their affinity for the lectin concanavalin-A. A monoclonal antibody was prepared by the hybridoma technique agains the Con-A-binding fraction. This antibody and a commercial polyclonal antibody against bovine serum albumin were used to examine the relationship between those proteins, serum albumin and alpha-2HS glycoprotein, two proteins concentrated within dentin and bone matrices. The Con-A-unbound fraction reacted with the anti-albumin antibody and the antibody against the Con-A-binding fraction recognized the alpha-2HS glycoprotein. These data fully support the presence of significant levels of proteins related to serum components in the mineral compartment of developing enamel matrix.