Roberto Cleymaet

Development and testing of bioadhesive, fluoride-containing slow-release tablets for oral use.

Abstract— The bioadhesive characteristics of tablets for oral use made from modified starch, polyacrylic acid (PAA), polyethylene glycol (PEG) and sodium carboxymethylcellulose (CMC) were investigated. Adhesion force and energy were determined in‐vitro and maximal adhesion time was evaluated in‐vivo in human subjects. In‐vitro, PAA showed the best bioadhesive properties, followed by modified maize starch and PEG with a mol. wt of 300 000–400 000 daltons. The presence of 0·1 mg of fluoride as NaF did not lead to significant differences in adhesion force and energy for the same formulation. The in‐vivo bioadhesion was not strongly correlated to the in‐vitro data. PAA, despite its excellent adhesion, proved to be irritating to the mucosa. PEG with a mol. wt of 200000 daltons was subject to erosion. CMC showed good bioadhesive properties but the mechanical strength of the tablets was low. Modified maize starch tablets containing 5% (w/w) PAA and PEG with a mol. wt of 300 000 daltons proved to be the most suitable formulations for a fluoride‐slow‐release tablet with bioadhesive properties. In‐vitro, the tablets released all of the fluoride within the 8 h period, with a high initial release. The release rate was related to the water absorption rate of the tablets. The PAA‐containing formulations and the CMC formulations had the fastest release. In‐vivo, fluoride levels with a minimum of 150 and a maximum of 1000 μg mL−1 were maintained for 8 h in the oral cavity. These fluoride levels were sustained significantly longer than those obtained with the administration of fourfold the amount of fluoride in the form of a fluoride‐containing toothpaste. The release characteristics in‐vivo exhibited a high variation. The use of bioadhesive polymers in oral pharmacotherapy seems promising.

Immediate single‐tooth implants in the anterior maxilla: 3‐year results of a case series on hard and soft tissue response and aesthetics

PURPOSE The objective of this prospective study was to assess the overall outcome of immediate single implant treatment in the anterior maxilla after a 3-year observation period. MATERIAL AND METHODS Thirty consecutively treated patients with a thick gingival biotype, ideal gingival level/contour and intact socket walls at the time of tooth extraction were treated for single-tooth replacement in the aesthetic zone by two experienced clinicians. Treatment included minimal mucoperiosteal flap elevation, immediate implant placement (NobelReplace TiUnite(®)), insertion of a grafting material between the implant and the socket wall and connection of a screw-retained provisional restoration. The latter was replaced by a cemented crown 6 months thereafter. Patients were clinically and radiographically re-examined after 3 years to assess implant survival, complications and hard and soft tissue conditions. The aesthetic outcome was objectively rated using the Pink Esthetic Score (PES) and White Esthetic Score (WES) by a blinded clinician who had not been involved in the treatment. RESULTS Twenty-five patients could be re-evaluated after 3 years. One early implant failure had occurred resulting in an implant survival rate of 96%. Radiographic examination yielded on average 1.13 mm mesial, respectively 0.86 mm distal bone loss. The clinical conditions showed fairly low peri-implant plaque (18%) and bleeding (24%) and mean probing depth was 3.17 mm. Mean mesial/distal papilla shrinkage and midfacial soft tissue recession in reference to the pre-operative status accounted for 0.05, 0.08 and 0.34 mm, respectively. Between the 1- and 3-year reassessment mesial papillae showed significant re-growth (0.36 mm; p=0.015). Advanced midfacial recession (>1 mm) was found in 2/25 (8%) cases. Five (21%) cases were aesthetic failures (PES<8 and/or WES<6) and 5/24 (21%) showed an (almost) perfect outcome (PES≥12 and WES≥9). The remainder (14/24 or 58%) demonstrated acceptable aesthetics. CONCLUSIONS The proposed strategy seems a valuable and predictable treatment option for well-selected patients in the mid-long term as shown by almost full papillary re-growth and a low risk for advanced midfacial recession.

Soft Tissue Preservation and Pink Aesthetics around Single Immediate Implant Restorations: A 1-Year Prospective Study

PURPOSE (1) To document soft tissue aspects using a specific protocol for immediate implant treatment (IIT) following single-tooth removal; (2) to evaluate whether this protocol allows preservation of pink aesthetics as objectively assessed. MATERIALS AND METHODS Patients with a thick gingival biotype and intact buccal bone wall upon extraction of a single tooth in the aesthetic zone (15-25) were consecutively treated. The protocol included flapless extraction and implant surgery, socket grafting, immediate nonocclusal loading with a screw-retained provisional crown, and replacement by a permanent crown 6 months thereafter. The outcome was assessed after 3, 6, and 12 months. Cases demonstrating major alveolar process remodeling and/or advanced midfacial recession (>1 mm) at 3 months were additionally treated with a connective tissue graft (CTG). The emergence profile of the provisional crown was replicated for all permanent crowns. RESULTS Twenty-two patients (12 men, 10 women; mean age 50) were treated after tooth extraction for nonperiodontal reasons using a novel bone condensing implant with variable-thread design, conical connection, and platform switch (NobelActive®, Nobel Biocare, Göteborg, Sweden). One implant failed and mean marginal bone loss was 0.1 mm (p = .059). Temporary mesial papilla reduction occurred, whereas distal papilla reduction was permanent (mean 0.5 mm; p = .001). At 3 months, five cases demonstrated major alveolar process remodeling and two advanced midfacial recession. Hence, slight initial decline in the pink esthetic score (PES) (p = .053) was observed. CTG resulted in a steady improvement of the PES after 3 months (p ≤ .037). At 12 months, pink aesthetics (mean PES 12.15) was comparable to the preoperative status (mean PES 11.86; p = .293). Distal papillae had significantly deteriorated (p = .020) in this time span, whereas midfacial contour had significantly improved (p = .005). CONCLUSIONS Preservation of pink aesthetics is possible following IIT. However, to achieve that, CTG may be necessary in about one-third of the patients. Major alveolar process remodeling is the main reason for additional treatment.

Four Modalities of Single Implant Treatment in the Anterior Maxilla: A Clinical, Radiographic, and Aesthetic Evaluation

PURPOSE To document the outcome of single implants in the anterior maxilla following four routine treatment modalities when performed by experienced clinicians in daily practice using the same implant system and biomaterials. MATERIAL AND METHODS A retrospective study in patients who had been treated by two periodontists and two prosthodontists in 2006 and 2007 was conducted. The four treatment modalities practically covered every clinical situation and included standard implant treatment (SIT), immediate implant treatment (IIT), implant treatment in conjunction with guided bone regeneration (GBR), and implant treatment in grafted bone (BGR) harvested from the chin. All implants were installed via flap surgery. Patients were clinically and radiographically examined. Complications were registered and the aesthetic outcome (pink esthetic score [PES] and white esthetic score [WES]) was rated. A blinded clinician who had not been involved in the treatment performed all evaluations. Patients aesthetic satisfaction was also registered. RESULTS One hundred four out of 115 eligible patients (44 SIT, 28 IIT, 18 GBR, and 14 BGR) received at least one single NobelReplace tapered TiUnite® (Nobel Biocare, Göteborg, Sweden) implant in the anterior maxilla and were available for evaluation. Clinical parameters (implant survival: 93%, mean plaque level: 24%, mean bleeding on probing: 33%, and mean probing depth: 3.2 mm) and mean bone level (1.19 mm) did not differ significantly between treatment modalities. Postoperative complications were more common following GBR/BGR (>61%) when compared with SIT/IIT (<18%) (p < .001). BGR was in 4/14 patients associated with permanent sensory complications at the donor site. Technical complications occurred in 9/104 patients. SIT and IIT showed similar soft tissue aesthetics (PES: 10.07 and 10.88, respectively), however major alveolar process deficiency was common (>15%). PES was 9.65 for GBR. BGR showed inferior soft tissue aesthetics (PES: 9.00; p = .045) and shorter distal papillae were found following GBR/BGR (p = .009). Periodontal disease (odds ratio [OR]: 13.0, p < .001), GBR/BGR (OR: 4.3, p = .004), and a thin-scalloped gingival biotype (OR: 3.7, p = .011) increased the risk for incomplete distal papillae. WES was 7.98 for all patients considered. Poor agreement was found between objective and subjective aesthetic ratings. CONCLUSIONS All treatment modalities were predictable from a clinical and radiographic point of view. However, advanced reconstructive surgery, especially BGR, increased the risk for complications and compromised aesthetics. Research is required on the prevention and minimally invasive treatment of buccal bone defects at the time of tooth loss to avoid complex therapy.

Load dependency and reliability of microhardness measurements on acid-etched enamel surfaces

The load dependency of hardness measurements was investigated on sound and demineralized enamel samples. For all samples investigated, the Knoop hardness number (KHN) varied as a function of the applied load. Higher loads enhanced indenter penetration into the test surface. The variation in KHN values observed in demineralized enamel, both surface-softened and surface-etched, was explained by a decrease in porosity as a function of depth. The reading error for indentations made on surface enamel etched with 37% phosphoric acid gel for 30 s was found to be slightly elevated compared to indentations made on a polished sound enamel surface. It was concluded that the surface microhardness technique can be used for the longitudinal investigation of etched surface enamel.

Comparison of salivary fluoride concentrations after administration of a bioadhesive slow‐release tablet and a conventional fluoride tablet

Abstract— The in‐vitro and in‐vivo fluoride release of bioadhesive, slow‐release tablets prepared from a mixture of polyethylene glycol polymers, containing 0·1 mg of fluoride as NaF was studied, and their ability to sustain fluoride levels in saliva were compared with conventional fluoride tablets with the same fluoride content. In‐vitro release experiments showed that the bioadhesive tablets needed 8 h to release all their fluoride compared with < 1 h for the conventional fluoride tablets. In‐vivo, the bioadhesive tablets had a retention period of 6 h and could sustain a salivary fluoride level of more than 10 μm above the baseline for 7 h. The conventional fluoride tablets achieved a peak concentration of 0·5 Mm directly after dissolution in the mouth, but the fluoride level could not be sustained for longer than 1 h. A good agreement was found between the in‐vitro swelling behaviour of the bioadhesive tablets and their in‐vitro and in‐vivo release characteristics and their in‐vivo retention time.

Single Implant Treatment in Healing versus Healed Sites of the Anterior Maxilla: A Clinical and Radiographic Evaluation

PURPOSE The aim was to document the Nobelreplace tapered TiUnite® (Nobel Biocare, Göteborg, Sweden) implant system used by experienced clinicians in daily practice for replacing single maxillary anterior teeth and to compare the clinical and radiographic outcome between implants installed in healing sites (early implant placement) and fully healed sites (conventional implant placement) after on average two and a half years of function. MATERIAL AND METHODS A cross-sectional study in patients who had been treated by two periodontists and two prosthodontists in 2006 and 2007 was conducted. Surgical treatment involved standard flap elevation without releasing incisions and restorative procedures included cemented crowns in all patients. Only straightforward single implant treatments in healing sites (6-8 weeks following tooth extraction) and fully-healed sites (≥6 months following tooth extraction) were considered with both neighboring teeth present and without the need for hard and/or soft tissue grafting. Clinical and radiographic analyses of all implants were performed by a blinded clinician who had not been involved in the treatment. RESULTS Forty-nine of the 53 eligible single implants (22 early and 27 conventionally placed implants) in 44/48 patients were available for scrutiny. There was no significant difference in implant survival between early (95%) and conventionally (93%) installed implants (p = 1.000). Mean bone level to the implant-abutment interface was 1.25 and 1.02 mm for early and conventional implant placement, respectively (p = .220). In spite of fairly low plaque levels (26%), overall peri-implant bleeding was quite prevalent (36%). Mean peri-implant probing depth was 3.3 mm. Five restorations had experienced technical complications. CONCLUSIONS Single Nobelreplace tapered TiUnite® implants installed in healing as well as in healed sites of the anterior maxilla are predictable. Both strategies seem equally successful in terms of implant survival, bone remodeling, clinical response, and risk for complications.

Acid-etched enamel surfaces after 24 h exposure to calcifying media in vitro and in vivo

The remineralization of acid-etched enamel lesions is investigated in this study both in vitro and in vivo over periods of 24 h. In an initial study, samples of etched bovine enamel were subjected in vitro to treatment with synthetic calcifying solutions, or were exposed to saliva by means of an intraoral appliance. Alterations in hardness of the enamel surface were measured by indentation techniques. In a second study the suitability of an impression technique for investigating the surface relief induced by an acid-etch procedure was investigated. Extracted human incisors were used to make SEM observations of eteched areas and corresponding sections of impressions. Subsequently, six subjects were selected for a clinical evaluation of the impression technique. Although a significant decrease in indentation length (increase in hardness) was observed for etched enamel lesions treated with calcifying solutions in vitro, no evidence for any such change was observed in samples exposed to the influence of saliva when investigated by the indentation and impression techniques.

Regenerative periodontal therapy of infrabony defects using minimally invasive surgery and a collagen‐enriched bovine‐derived xenograft: a 1‐year prospective study on clinical and aesthetic outcome

AIM To evaluate the clinical and aesthetic outcome of regenerative periodontal therapy (RPT) using minimally invasive surgery and a collagen-enriched bovine-derived xenograft (1); to identify risk factors for failure (clinical attachment level (CAL) gain ≤ 1 mm) and advanced gingival recession (REC) increase (>1 mm) (2). MATERIAL AND METHODS Ninety-five non-smoking patients, with ≤ 25% full-mouth plaque and bleeding presenting ≥ 6 months after initial periodontal therapy with ≥ 1 isolated inter-dental infrabony defect were recruited. Patients were consecutively treated by the same clinician using minimally invasive surgery and a collagen-enriched bovine-derived xenograft. Clinical, radiographic and aesthetic data were collected before surgery and up to 1 year. Multivariate analyses were used to identify risk factors for failure and advanced REC increase. RESULTS Eighty-four patients (39 men, 45 women; mean age 53) complied and demonstrated mean probing depth (PD) of 7.8 mm, CAL of 10.0 mm and defect depth of 5.2 mm before surgery. At 1 year, postsurgery mean PD reduction was 3.5 mm (range 0.0-8.0), CAL gain was 3.1 mm (range 0.0-7.0) and radiographic defect fill was 53% (range 0-100). Forty-nine percentage showed ≥ 4 mm CAL gain, whereas 15% were considered failures. Mean inter-dental and midfacial REC increase was 0.3 mm (range-2.0-2.0) and 0.5 mm (range-1.5-2.0) respectively. Midfacial REC increase and contour deterioration contributed most to a small, yet significant reduction in the Pink Esthetic Score from 10.06 to 9.42 (p = 0.002). Risk factors for failure included defects with a non-supportive anatomy (OR: ≥ 10.4), plaque (OR: 14.7) and complication(s) (OR: 12.0). Risk factors for advanced midfacial REC increase included defects with a non-supportive anatomy (OR: 58.8) and a thin-scalloped gingival biotype (OR: 76.9). CONCLUSIONS RPT using minimally invasive surgery and a collagen-enriched bovine-derived xenograft demonstrated favourable clinical outcome after 1 year, even though soft tissue aesthetics could not be fully preserved. Defects with a non-supporting anatomy may be at risk for failure and advanced midfacial recession.

Predictors of alveolar process remodeling following ridge preservation in high-risk patients

PURPOSE (1) To clinically evaluate horizontal remodeling of the alveolar process (hard and soft tissues) following ridge preservation in high-risk patients and (2) to identify predictors of such remodeling. MATERIALS AND METHODS Periodontally healthy nonsmoking patients with a failing tooth in the anterior maxilla (15-25) were selected for a prospective case series. All were in need of a single implant and demonstrated high risk for aesthetic complications given an incomplete buccal bone wall and/or thin-scalloped gingival biotype. Following flapless tooth extraction, ridge preservation was performed using one or more collagen-enriched, bovine-derived block grafts (Geistlich Bio-Oss® Collagen® 100 mg, Geistlich Pharma AG, Wolhusen, Switzerland) without the additional use of membranes or soft tissue grafts. The change in buccopalatal dimension of the alveolar process between baseline (prior to tooth extraction) and 4 months was assessed on the basis of superimposed occlusal slides. Regression analysis was performed to identify predictors of alveolar process remodeling. RESULTS Forty-two patients (21 females, 21 males; mean age 38) met the selection criteria and consented to the treatment. Mean alveolar process remodeling was 14% (SD 7, range 4-30) with minimal remodeling (≤ 10%) in 16 patients (38%) and advanced remodeling (>20%) in 10 patients (24%). A single implant could be installed in all subjects without additional guided bone regeneration. Connective tissue grafting was performed later on in the treatment for aesthetic purposes, hereby compensating for tissue loss at the buccal aspect. Predictors of alveolar process remodeling were tooth location (central incisors and cuspids > laterals incisors and premolars), tooth abscess (p = .025), and buccal bone loss (p = .035). CONCLUSION Alveolar process remodeling seems inevitable yet acceptable following ridge preservation in high-risk patients. Proper case selection may reduce the incidence of advanced remodeling.