International Journal of Periodontics & Restorative Dentistry, 04/2010

Adequately contoured implant restorations need to transition from the circumferential design of the implant head to the correct cervical tooth anatomy. The implant abutment may be used to effect this transition provided there is sufficient running room. Implant restorations have been described as overcontoured, flat, and undercontoured. It has been shown that overcontouring will generally cause apical positioning of the gingival margin, while undercontouring will induce the opposite effect. However, these terms have been applied arbitrarily and without allocating specific determinants. Furthermore, the concept of "contour" as originally adapted from tooth-supported restorations needs to be redefined as it pertains to implant dentistry. Two distinct zones within the implant abutment and crown are defined as critical contour and subcritical contour. Any alteration of critical or subcritical contour can modify the soft tissue profile. The purpose of this paper is to determine the effect of abutment contour modifications at these zones on the peri-implant soft tissues, including the gingival margin level, papillae height, gingival architecture, labial alveolar profile, and gingiva color.

Transverse expansion or proclination of the teeth are valid alternatives to extraction in cases of crowding, but lack of stability and development of bone dehiscences have been demonstrated as side effects subsequent to anterior displacement of the incisors. The aim of this study was to repair the osseous dehiscence associated with incisor proclination. The multiple adjacent bone dehiscences were treated with a titanium membrane and bone matrix. Exposed root surfaces were covered with newly formed tissues. The patients in this study are the first to demonstrate the treatment of bone dehiscences that may occur as a result of orthodontic proclination.

This paper presents ultrasonic surgery (ie, Piezosurgery) as a new, relevant, and predictable method for performing atraumatic tooth extraction and subsequent implant site preparation. Forty noninfected teeth or roots were extracted in 23 patients and replaced immediately with implants. Extraction consisted of cutting the fibers of the periodontal ligament with vibrating tips of up to 10 mm in depth; the teeth or roots were mobilized afterward with an elevator. All teeth/roots were removed without fracture. Implant osteotomies were performed using conical tips of increasing diameters. During implant placement, notching of the apical third of the palatal wall or the interradicular bridge was performed without complication due to uncontrolled movements of the instrument. After a mean healing period of 2.4 months, all implants were osseointegrated and have been successfully loaded for at least 12 months. By implementing Piezosurgery, extraction can be atraumatic and implant placement can be predictable and undemanding compared to the use of burs, which can lead to instruments slipping during the procedure.

Recent advancements in the arena of therapeutic molecular enhancement have shown favorable clinical findings for periodontics. However, further studies to optimize clinical outcomes using this technology are warranted. Twelve premolar extraction sockets were assigned randomly for treatment with 0.3 mg/mL recombinant human platelet-derived growth factor (rhPDGF-BB) combined with either a collagen containing anorganic deproteinized bovine bone (xenograft) or betatricalcium phosphate (ß-TCP). Histologic evaluation of extraction socket healing was performed at 3 months. Histologic findings were similar with ß-TCP and the xenograft, having 21% and 24% vital bone, respectively. The use of rhPDGF-BB with either ß-TCP or a xenograft resulted in uneventful socket healing. At reentry, all implants were placed without the need for further grafting, and 100% implant success was recorded at the time of final evaluation (restoration completion).

An esthetic implant-supported rehabilitation continues to be a major challenge in patients with a thin periodontium. Ridge preservation and immediate implant placement are intended to preserve the hard tissue volume and prevent preimplant bone loss following tooth extraction. Since these techniques are almost always combined with bone grafting, primary wound closure is indispensable. Therefore, a technique for reliable wound closure was developed. This technique employs a combined epithelized-subepithelial connective tissue graft, leaves the mucogingival line in its place, and has the added advantage of thickening the buccal soft tissue with the resultant local conversion of a thin marginal gingiva to a thick marginal gingiva.

The aim of this report is to investigate the efficacy of the sandwich technique for vertical bone augmentation in the atrophic posterior mandible of three patients through clinical and histologic studies. A complete osteotomy was conducted using a piezoelectric device to create segmented bone in the atrophic edentulous area and the segmented bone was elevated 6 mm vertically. Interpositional mineral allograft materials were inserted in the space between the basal bone and the segmented bone. After a mean 5-month healing period, bone biopsies were taken in the grafted areas and implants were placed. Six millimeters of vertical bone gain was achieved in all patients by using the sandwich technique. Histomorphometric analysis of the biopsy specimens showed favorable new bone formation without inflammation.

Traumatic tooth fractures represent an intriguing challenge for clinicians, particularly when they involve the anterior region of the maxilla. In such situations, esthetic, psychosocial, functional, and therapeutic problems may have a negative effect on the patient's quality of life. In addition, fractures that involve the biologic width of the periodontium are even more difficult to treat. An interdisciplinary approach based on crown lengthening with or without orthodontic extrusion and the definitive prosthetic rehabilitation represent the standard modality of treatment for these conditions to restore the appropriate biologic dimension and to reduce the damage esthetically. However, if the margins of the fragment and the tooth show perfect juxtaposition with no interfragmentary space, an adhesive technique may be indicated. The aim of this case report is to describe the treatment of a severe subgingival tooth fracture by means of adhesive reattachment of the fragment followed by a periodontal evaluation over a 15-month period.

The purpose of this study was to evaluate the short- and mid-term prognosis of maxillary and mandibular single molar implants, prosthetic complications, and factors mediating the effects seen on them. Eighty-seven patients were enrolled consecutively in this study and 96 implants were placed into a single molar defect site by one oral and maxillofacial surgeon from March 2004 to December 2006. Primary osseointegration failure developed in two implants and delayed implant failure occurred at four implants. The fraction surviving interval was 97% to 100%, and at the last follow-up observation, the cumulative survival rate was 91.1%. All failed implants occurred in second molar sites, and the failure rate, according to implant site, showed a significant difference. Prosthetic complications, such as screw loosening, showed a significant correlation to the mesiodistal cantilever. Furthermore, crestal bone loss 3 years after loading was 0.2 mm on average and a very stable result was obtained. Based on the results, the risk of failure for maxillary and mandibular single molar implants is high and the possibility of developing prosthetic complications during loading is also high. Therefore, to minimize the cantilever, implants must be placed precisely and followed carefully and maintained for a long period of time.

This study investigated whether surface topography affects the retentive strength of cemented full crowns, comparing the effects of standard machined, sandblasted, and grooved implant abutments. Five metallic crowns per abutment type were cast and cemented with zinc phosphate. After 24 hours, the specimens were submitted to a tensile test. The retentive strength of the cemented crowns was affected by abutment surface topography. The sandblasted and grooved surface groups had approximately 2.4 times greater mean uniaxial retentive strength than the machined surface group (P .001). The retentive strength of the sandblasted and grooved abutments was similar, despite marked differences in surface profiles and roughness parameters.

The purpose of this study was to present a new laboratory technique for cementable implant-supported restorations and to evaluate its efficacy in reducing chair time for both patients and clinicians, while maintaining the precision of an indirect procedure for crown fabrication. The technique consisted of the duplication of the implant portion of a working cast prepared using double-pour or plastic base die systems for single or multiple crowns. For this purpose, a flask previously intended for the production of ceramic inlays and onlays was used. Duplication was obtained using a high-precision addition silicon material and a low-shrinkage polyurethane resin. The duplicated implant abutment was used to finalize the fixed partial denture restorations after the originals were delivered to the patients. Fifty abutments were tested consecutively. The castings (19 single crowns, 31 fixed partial dentures) produced on the original abutments were seated on the duplicate abutments and evaluated by two prosthodontists and two dental technicians using a visual inspection method (laboratory microscope at 16X magnification). Forty-eight restorations were "good" (completely seated, no marginal opening) and 2 were "acceptable" (incomplete seating but amendable), with a 98% success rate. The technique presented demonstrates efficacy and predictability in reducing the number of clinical sessions for delivering precisely fitting cementable implant-supported restorations.