International Journal of Periodontics & Restorative Dentistry, 03/2012

The purpose of this study was to determine the effect of cigarette smoking and residual native bone height on the survival of dental implants placed immediately in grafted sinuses. In this retrospective study, 334 subject records were screened, and 75 subjects (155 implants) were included. Data collection based on treatment notes and radiographs included age, sex, smoking status, sinus floor bone height, dental implant information, and implant survival. The survival rates of implants for nonsmokers and smokers at stage-two surgery were 93% and 84%, respectively. After 12 months of functional loading, the survival rates of implants for nonsmokers and smokers were 87% (81 of 93) and 79% (49 of 62), respectively (P .000). Analysis revealed that the effect of smoking on implant survival is significant when the preoperative bone height is less than 4 mm, with an 82.4% implant survival rate in nonsmokers compared to 60% in smokers (P .05). Smoking should be considered as a high risk factor when implants are placed immediately in grafted sinuses, particularly in areas of limited bone height.

The purpose of this case report is to demonstrate the effectiveness of a matrix consisting of recombinant human platelet-derived growth factor BB (rhPDGF-BB)-hydrated cancellous allogenic block graft in the reconstruction of large local human alveolar ridge defects. The results suggest improved bone regeneration when combining rhPDGF-BB with the allogenic block graft. The clinical and histologic evidence of new bone formation as well as bone remodeling supports the clinical potency of this growth factor- mediated therapy.

Soft tissue augmentation around dental implants in the esthetic region remains a challenging and unpredictable procedure. The ideal surgical technique would include of an off-the-shelf product to minimize morbidity after autogenous grafting procedures. The aim of this study was to use a resorbable collagen matrix (Mucograft) to serve as a scaffold to recombinant human platelet-derived growth factor BB (rhPDGF-BB) to increase peri-implant soft tissue volume in anterior maxillary sites. A total of six patients who had previously undergone a bone regeneration procedure were included in this study. The collagen matrix was applied during stage-two surgery (expanded polytetrafluoroethylene membrane removal and implant placement). Measurements were performed through customized stents by means of endodontic files, and at abutment connection, a soft tissue biopsy specimen was harvested for histologic examination. The healing period was uneventful in all six patients. Measurements were taken apically, centrally, and occlusally for each site. The mean gains in volume from baseline to the 4-month measurement at the apical, central, and occlusal aspects were 0.87 ± 2.13 mm, 2.14 ± 3.27 mm, and 0.35 ± 3.20 mm, respectively. The results showed a moderate increase in the soft tissue volume in esthetic peri-implant sites when applying a collagen matrix infused with rhPDGF-BB. However, the measuring techniques available need to be further improved to record exact changes in the soft tissue volume.

Recombinant human growth/differentiation factor 5 (rhGDF-5) and recombinant human bone morphogenetic protein 2 (rhBMP-2), as members of the transforming growth factor ß family, influence bone formation and differentiation. This in vitro osteoblast cell culture study investigated the molecular biologic effect of these growth factors on regulator gene expression of the homebox proteins MSX1 and MSX2 as well as distal-less homebox 5 (Dlx5) and runt-related transcription factor 2 (Runx2/Cbfa1). Concerning effector genes, the messenger ribonucleic acids of osteocalcin (OCN) were quantified using a reverse transcriptase realtime polymerase chain reaction. Over a period of 15 days, osteoblasts were stimulated and analyzed at days 1, 2, 5, 10, and 15. rhGDF-5 and rhBMP-2 were applied in concentrations of 100, 500, and 1,000 ng/mL. The results showed enhanced gene expression of MSX1 and MSX2 by the lower rhGDF-5 concentration (100 ng/mL) during the first 48 hours and a marginally enhanced gene expression of Runx2 and OCN in a dose-dependent manner. The rhBMP-2 stimulation showed enhanced MSX1 and MSX2 gene expression with peaks at 24 and 240 hours; Runx2 and OCN were more highly expressed than the unstimulated control with the 100-ng/mL concentration. rhGDF-5 seems to stimulate early osteoblast differentiation and extracellular matrix production, while rhBMP-2 seems to boost early and late osteoblast differentiation. Low growth factor concentrations appeared to be more effective in terms of gene expression.

Among the graft materials that can be used clinically, xenografts are the most common. Xenografts are of bovine, porcine, or equine origin and require the complete removal of proteins to avoid immunologic problems and the risk of transmission of prions, viruses, etc. Protein destruction can be achieved by a chemical procedure using organic solvents and heat treatment. After this process, a carbonated hydroxyapatite similar to human bone remains. The aim of this case report is to investigate the bone formation in a sinus augmentation procedure using a high temperature-treated bovine porous hydroxyapatite. A 58-year-old woman underwent bilateral sinus augmentation using this biomaterial. After 9 months, during stage-two surgery, two core biopsy specimens were retrieved and treated to obtain thin ground undecalcified sections. Microscopically, newly formed bone was present at the interface with most particles. The major portion of the particles appeared to be completely lined and surrounded by bone. No obvious signs of resorption were present on the biomaterial surface. No gaps or connective tissue were present at the bone-biomaterial interface. No inflammatory infiltrate or fibrous encapsulation of the particles was present. Histomorphometry showed that the percentages of newly formed bone, residual grafted particles, and marrow spaces were 25.1% ± 2.3%, 37.3% ± 1.1%, and 38.5% ± 3.1%, respectively. The excellent properties demonstrated by Endobon are probably a result of its particular hydroxyapatite porous microstructure with a high percentage of interconnected micropores that promote the ingrowth of osteogenic cells and vessels, making graft integration easier and faster.

The aims of this in vivo study were to compare the effectiveness and color stability of at-home and in-office bleaching techniques and to evaluate whether the use of light sources can alter bleaching results. According to preestablished criteria, 40 patients were selected and randomly divided into four groups according to bleaching treatment: (1) at-home bleaching with 10% carbamide peroxide, (2) in-office bleaching with 35% hydrogen peroxide (HP) without a light source, (3) in-office bleaching with 35% HP with quartz-tungsten-halogen light, and (4) in-office bleaching with 35% HP with a lightemitting diode/laser. Tooth shade was evaluated using the VITA Classical Shade Guide before bleaching as well as after the first and third weeks of bleaching. Tooth shade was evaluated again using the same guide 1 and 6 months after the completion of treatment. The shade guide was arranged to yield scores that were used for statistical comparison. Statistical analysis using the Kruskal-Wallis test showed no significant differences among the groups for any time point (P > .01). There was no color rebound in any of the groups. The bleaching techniques tested were equally effective. Light sources are unnecessary to bleach teeth.

Guided bone regeneration has been shown to be a successful technique to increase the ridge width for dental implant placement. However, in cases of severe or localized horizontal bone deficiencies, achieving sufficient soft tissue mobilization to ensure primary wound closure over the augmented area can be difficult. This article describes a buccal periosteal pocket flap proposed to overcome these challenges. The flap design results in a periosteal pocket, which allows filling of bone-grafting material while facilitating primary tension-free soft tissue closure by splitting of the mucosa. The flap gives stability to the augmented volume within the pocket. Ridge widths of five patients consecutively treated with this technique were recorded before and 24 weeks after augmentation. Results from these cases showed a mean 389% ± 301% gain in bone width (range, 50% to 1,420%) when the periosteal pocket flap design was used. Data obtained from this study suggest that the periosteal pocket flap design could be a predictable alternative flap approach for correction of severe or localized horizontal bone deficiencies.

Most of the histologic studies found in the literature on the peri-implant soft tissues have been done in animals and usually have been confined to mandibular implants fitted with healing or standard abutments. Few studies have investigated human peri-implant soft tissues. Moreover, the structure and dimensions of the peri-implant soft tissues in immediately loaded implants have not been investigated in depth. Human histologic data are valuable to validate animal models. This histologic and histomorphometric study evaluated the peri-implant soft tissues around three immediately loaded implants in humans. The implants were retrieved using a trephine and treated to obtain thin, ground sections. The sulcular epithelium was composed of approximately four to five layers of parakeratinized epithelial cells and had a length of approximately 1.2 to 1.3 mm. The junctional epithelium was composed of approximately three to four layers of epithelial cells and had a length of approximately 1.0 to 1.5 mm. Connective tissue attachment had a width of between 400 and 800 µm. Peri-implant collagen fibers, in the form of bundles (1- to 5-µm thick), began at the crestal bone and were oriented perpendicular to the abutment surface until 200 µm from the surface, where they became parallel running in several directions. Collagen fibers appeared to form a three-dimensional network around the abutment. No acute or chronic inflammatory cell infiltrate was present. Collagen fibers oriented in a perpendicular manner and in direct contact with the abutment surface were not observed in any of the specimens. This differentiated network of fibers may have clinical relevance as a mechanical protection of the underlying bone. These human histologic data are extremely valuable to validate and confirm those obtained from studies performed on animal models. Moreover, immediate loading of the implants did not compromise soft tissue integration.

Many studies have shown that alloplastic bone grafts are clinically stable and safe. Nevertheless, postoperative problems such as ankylosis and root resorption are associated with alloplastic bone grafts. This report examined two cases of ankylosis of nonresorbable hydroxyapatite (NHA) alloplastic grafts associated with recurrent periodontitis. There was no clear border between the NHA particles and dentin. The particles were irregularly shaped and had plaque on the surfaces. It is postulated that ankylosis of NHA particles and dentin is a contributing factor in recurrent periodontitis.

Immediate loading procedures may cause discomfort to the patient and increase the possibility of damage to the surgical site during prosthetic restorations. The aim of this clinical report is to describe an alternative method to fabricating a mandibular hybrid prosthesis in 3 days without taking an impression. Five implants were placed in the anterior region of an edentulous mandible and restored with a definitive mandibular hybrid prosthesis using a unique acrylic resin framework. This acrylic resin framework enabled the fabrication of the metal framework of the mandibular hybrid prosthesis without taking a final impression. The step-by-step technique is described.

The aim of this paper is to present a new approach to bone regeneration in a patient with multiple recurrent ameloblastoma of the left mandibular angle. Through an extraoral approach, complete resection of the tumor was achieved. Bone marrow aspirate from the iliac crest was centrifuged to concentrate the mesenchymal cellular fraction. Based on a stereolithographic cast, titanium mesh was bent preoperatively to accurately reconstruct the mandibular angle. The mesh was filled with two blocks of xenogenic material mixed with recombinant bone morphogenetic protein 7 (BMP-7) and stem cells. Nine months later, three endosseous implants were placed in the regenerated bone to restore the patient's masticatory function. At this time, bone samples were obtained for histomorphometric analysis. New bone formation was confirmed around the particles of xenograft material. The results indicate that adequate esthetics and function may be achieved with bone marrow aspirate seeded on a scaffold obtained from bovine xenograft blocks and BMP- 7. This technique attains new bone formation with sufficient quantity and quality to allow for implant placement, with decreased patient morbidity and surgical time compared to conventional reconstructive methods.

The purpose of this randomized clinical trial was to determine the clinical wear behavior of three nanofilled composites (Filtek Supreme XT [FS], Tetric EvoCeram [TEC], and Aelite Aesthetic [AA]) with two indirect composites (Estenia [E] and Tescera ATL [TATL]) on permanent molar teeth. Fifty-four patients whose treatment plans included moderate Class I and/or II restorations on molar teeth were selected for inclusion in this study. Wear was measured by use of gypsum replicas at baseline and 6 and 12 months using three-dimensional scanning and rapid-form software to elucidate the wear mechanisms. For statistical analyses, one-way analysis of variance and the Scheffé test were used. Statistical results revealed that wear behavior of TATL was significantly different from that of AA (P .05). No significant differences were detected between AA and E (P > .05) or between TEC, FS, and TATL composite resins (P > .05). The results showed similar clinical performance between the five composite resins evaluated. Therefore, composite resins may be indicated for the restoration of posterior teeth. However, the composition of the composite resin did affect the wear behavior of the composite material.

The aim of this research was to evaluate the effect of postpolymerization method on the color stability of resin-based composites. Samples of direct and indirect restorative materials were polymerized with two photo-curing units (Visio photo-curing oven system and LED Elipar Freelight 2). All samples were submitted to an initial chromatic analysis using a spectrometer and submitted to ultraviolet-accelerated artificial aging. The direct material showed less color change than the indirect material, independent of the photo-activation method used. Samples photo cured with the LED system showed less change than those photo cured with the Visio system. The postpolymerization oven did not improve the color stability of direct and indirect resin-based composites.

The purpose of this blind, randomized, controlled pilot investigation was to noninvasively determine bone mineral density (BMD) changes around endosseous implants placed in healthy patients who were administered the oral aminobisphosphonate alendronate. BMD was analyzed using computed tomography (CT) and grayscale imaging. Male patients (62 ± 12 years of age) were selected for placement of implants in a two-stage protocol. Patients requiring implants were initially seen for placement of half the total number of implants unilaterally in the maxilla or mandible, and each patient underwent a baseline CT scan. Six months from baseline, contralateral implants were placed with randomization into groups receiving 70 mg of alendronate weekly or a placebo, and a second CT scan was completed. Alendronate/placebo was discontinued after 6 months, and a CT scan was completed at 12 months. Patients returned for an exit evaluation and CT scan at 18 months. Hounsfield units were measured at implant placement and nonsurgical sites in the maxilla and mandible. Within the limitations of this study, results included: a decreasing trend in BMD surrounding an implant when alendronate was administered for 6 months starting at the time of implant placement, a less evident decreasing trend in BMD surrounding an implant when alendronate was administered for 6 months after the implant had successfully undergone osseointegration, and a trend suggesting BMD "rebound" when alendronate was discontinued for 6 months after initial drug administration starting either at the time of implant placement or after the implant had successfully undergone osseointegration for 6 months.

The aim of this research was to study the influence of the osteotome technique on insertion torque and stability values when compared with conventional surgical drilling of the implant site. A total of 20 implants (4-mm diameter, 8.5-mm long) were placed in the distal femural condyle of 10 New Zealand White rabbits. The implant sites were prepared by using either the conventional drilling technique as a control group (group A) or the osteotome technique (group B). Cutting torque and resonance frequency analyses (RFAs) were conducted at and after implant placement. The resulting values were subjected to correlation and comparative analyses between groups. Insertion torque measurements were conducted at three different levels of implant insertion: crestal, middle, and apical. Group B showed higher mean insertion torque and RFA values (P .05). No statistically significant correlation could be observed when comparing the mean torque values with RFA values (P > .05). Bone condensation before implant insertion in low-density bone led to higher mean insertion torque and RFA values. Within the limits of this experimental study, a benefit in using the osteotome technique was observed when dealing with low-density bone. Bone condensation can improve primary stabilization of implants.

This paper presents three cases of peri-implant mucosal defects that were successfully treated with a newly proposed "pouch roll" implant soft tissue augmentation technique. This procedure uses a de-epithelialized connective tissue layer during the first or second stage of implant surgery over the underlying dental implant without the need for sutures. At 2 weeks, healing was remarkable, with excellent plaque control. At 3 months, only minimal tissue shrinkage was evident. As a result, a 2- to 3-mm increase in the width of the keratinized tissue was noted around the augmented implant site. This technique is an atraumatic, versatile, and cost-effective surgical modality that enhances the peri-implant soft tissue over the ridge with a soft tissue thickness >= 3 mm. The pouch roll implant soft tissue augmentation procedure provides an easy and less traumatic correction of a mild to moderate buccal ridge deficiency by thickening the soft tissue around the dental implant.