The International Journal of Oral & Maxillofacial Implants, 06/2001

The aim of this study was to assess the quality of randomized controlled trials (RCTs) concerned with the effectiveness of oral implants and to create a trial register. A multilayered search strategy was used to identify all RCTs published by the end of 1999 in any language. The Cochrane Oral Health Group specialist register, PubMed, and personal libraries were searched. Seventy-four RCTs were identified. Forty-three articles, not presenting the same patient material, were independently assessed by 3 researchers using a specially designed form. A statistician assessed all trials for the appropriateness of statistics. The quality of each study was assessed on 7 items, including 3 key domains. Randomization and concealment allocation procedures were not described in 30 articles (70%). Reasons for withdrawals were not given in 10 reports(23%). No attempt at blinding was reported in 31 studies (72%). The quality of RCTs of oral implants is generally poor and needs to be improved.

There is limited dental literature evaluating the retentive capabilities of luting agents when used between metal components, such as cast metal restorations cemented onto machined metal implant abutments. This study compared the retentive strengths of 5 different classes of luting agents used to cement cast noble metal alloy crowns to 8-degree machined titanium cementable implant abutments from the Straumann ITI Implant System. Sixty prefabricated 5.5-mm solid titanium implant abutments and implants were used; 30 received the standard surface preparation and the other 30 received an anodized surface preparation. Anodized implant components were used to reflect current implant marketing. Sixty castings were fabricated and randomly paired with an abutment and implant. A total of 12 castings were cemented onto the implant abutment assemblies for each of the 5 different luting agents (zinc phosphate, resin composite, glass ionomer, resin-reinforced glass ionomer, and zinc oxide¨Cnon-eugenol). After cementation, the assemblies were stored in a humidor at room temperature prior to thermocycling for 24 hours. Each casting was pulled from its respective abutment, and the force at which ond failure occurred was recorded as retentive trength. A statistically significant difference was ound between the 5 cements at P ¡Ü .001. Of the cements used, resin composite demonstrated the highest mean retentive strength. Zinc phosphate and resin-reinforced glass-ionomer cements were the next most retentive, while glass ionomer and zinc oxide¨Cnon-eugenol cements demonstrated minimal retention. In addition, retention was not altered by the use of an anodized abutment surface. Keywords: cemented implant restorations, dental cements, dental implants

The effects caused by the implantation of bioabsorbable hydroxyapatite (HA) bound to a pool of bone morphogenetic proteins (BMPs) and other bone noncollagenous hydrophobic proteins mixed with anorganic bovine bone inside rabbit bone marrow were assessed. Within the interior of hollow cylindric titanium prototypes, the following biomaterials were inserted: (1) test group: HA containing a pool of BMPs and noncollagenous hydrophobic proteins mixed with anorganic bovine bone; (2) control group: HA without any protein mixed with anorganic bovine bone; and (3) negative control group: blood clot. The cylinders were placed surgically into the medial portion of the tibiae of 7 rabbits in a manner that allowed the biomaterials to contact just the bone marrow. Morphometric analysis showed that: (1) the biomaterials containing the protein mixture resulted in significantly less new bone than the biomaterials without such a mixture; (2) the group without the protein pool formed larger amounts of bone within the cylinder when compared to the negative control (blood clot only); and (3) the biomaterials containing the protein pool did not show any difference in relation to the negative control. It was concluded that a pool of BMPs and other bone noncollagenous hydrophobic proteins had an inhibitory effect on osteogenesis, and that the biomaterials without a protein pool formed a favorable substrate to bone formation.

The aim of this study was to evaluate the effects of coating implants with hydroxyapatite (HA) by an ion beam-assisted deposition (IBAD) method and to compare them with implants prepared with sandblasted and machined surfaces. Examination of osteoblast cultures displayed no difference in the secretion of alkaline phosphatase (ALP) between the various surfaces, but the IBAD-HA specimen showed low ALP secretion (P .05). Removal torque tests showed that implants coated with HA by the IBAD method had values similar to the implants with a sandblasted surface, but values for the machined-surface implants differed. Implants placed in a group of ovariectomized rabbits showed lower mechanical test values than implants placed in sham-operated rabbits (P .05). Implants coated with HA by the IBAD method demonstrated the highest mean bone-to-metal contact ratio on all threads and on the 3 best consecutive threads, followed by the implants with a sandblasted surface and implants with a machined surface (P .05). Hydroxyapatite-coated implants showed a slightly higher bone-to-implant contact ratio than sandblasted implants, but no statistically significant difference was seen between the 2 materials. The implants placed in ovariectomized rabbits showed lower amounts of bone-to-metal contact than the implants placed in sham-operated rabbits, but no statistically significant difference was seen between the 2 groups. Evaluation of bone volume on all threads and the 3 best consecutive threads showed no statistically significant difference among the different surface treatment groups, but lower bone volume was seen in the ovariectomized rabbits than in the shamoperated animals (P .05).

Osseous integration of dental implants depends on the use of proper surgical technique during site preparation, including the prevention of thermal injury to the surrounding bone. Heat generation during drilling has been reported to positively correlate with the production of forces at the surgical site. In this study, peak torque and axial load levels were measured during a drilling procedure into a polymeric material simulating the human mandible. Axial rotary milling was performed using 5 different twist drill designs (3i Irrigated Tri-Spade, 3i Disposable, Nobel-Biocare, Straumann, and Lifecore) of 15 to 20 mm in length and 2 to 2.3 mm in diameter, at a free-running rotational speed of 1,500 rpm and continuous feed rate of 3.5 mm/second, to a total depth of 10.5 mm. Ten drills representing each of the 5 types (n = 50) were subjected to 30 individual drill pecks and heat-sterilized every 3 pecks to determine the effects of cyclic mechanical and thermal loading on drill performance. Normal stress ()and shear stress () were calculated from the kinetic data and drill geometries. A drill efficiency coefficient (µ) was also calculated as the ratio of torsional resistance to translational resistance. Overall, the hypotheses of drill performance dependency on drill type as well as mechanical and thermal accumulated loading were tested and confirmed (P .05). The 5 drill types produced a range of normal stresses (2.54 to 5.00 MPa), shear stresses (9.69 to 29.71 MPa), and efficiency (1.16 to 3.16) during repeated testing. Scanning electron microscopic images revealed minor deformations in the cutting edges of the tri-spade drills following testing.

Between February 1995 and May 1996, 71 patients received treatment that involved 1 or more wide Screw-Vent implants. A total of 131 wide implants were placed. All patients were recalled 1 year after loading. Seven patients (14 implants) were lost to follow-up. Six implants were removed before completion of prosthetic treatment. One hundred eleven implants were evaluated at the recall examination. Almost all majority of patients (93 implants), it was a 17 months (range, 11 to 21 months). No implants were lost during the loading period. The overall survival rate was 95%. The survival rate for mandibular implants was 94%; for maxillary implants, it was 96%. These percentages were not statistically different. Crestal bone remodeling was examined using periapical radiographs. After 17 months in function, only 3 implants (2.5%) presented bone loss beyond the first thread.

Implant placement in the posterior maxilla often requires elevation of the sinus floor, which can be achieved through either the modified Caldwell-Luc or the crestal osteotome technique. The objectives of this study were to evaluate (a) the resistance to perforation of maxillary sinus membranes obtained from formaldehyde-fixed cadavers in vitro, (b) the frequency and extent of membrane perforations occurring after sinus floor elevation in cadavers using the crestal approach, and (c) the amount of membrane elevation (doming) that can be achieved using the crestal approach. Pretreatment of maxillary sinus membrane tissues with commonly used tissue softeners did not have a statistically significant effect on resistance to perforation. Maxillary sinus membranes were elevated 4 to 8 mm in formaldehyde-fixed cadavers using the osteotome technique; implants were placed. Of the 25 sites that received implants, only 6 showed perforations, as assessed by double-blind investigation after dissection of the lateral wall of the nose, allowing direct examination of the sinus cavity. Perforations were categorized as Class I (¡Ü 2 mm with exposure of the implant into the sinus cavity and loss of doming); Class II perforations (¡Ý 2 mm) were associated with proximity of the osteotomy site to the medial wall of the sinus or the presence of septae. These results indicated that the crestal osteotome approach compared favorably to the modified Caldwell-Luc technique as it relates to the frequency of maxillary sinus membrane perforations and the degree of achievable membrane elevation.

Expeditious postoperative appositional growth of bone to dental implants is desired for clinically successful fixation of oral implants. The present study was performed to evaluate the effect of applying a capacitively coupled electric field (CCEF) followed by functional loading on peri-implant osteogenesis in the dog mandible. Nine adult beagles were used in this study. All premolars on both sides of the mandible were removed from each dog. A physio-odontlam implant (POI, Ti-6AI-4v) with 2 stages (3.7 mm in diameter and 8.0 mm in length), whose surface had been treated with anodic oxidation and sandblasted, was placed into each test site by self-tapping. Daily application of CCEF (8 hours per day) was initiated on the day following surgery and continued for 14 days or 21 days. After CCEF treatment was finished for each period, a prosthetic abutment and a straight post were placed on each implant. Four days after placement of the post, implants were placed under functional loading for 30 days. The dogs were then sacrificed, and histologic and radiographic studies of the mandible were performed. Relatively well calcified, mature bone with a lamellar-like structure was observed by contact microradiography and histologic study (double staining with basic fuchsin-methylene blue) of the peri-implant region on the CCEF-treated samples. In contrast, poorly calcified, immature bone without a lamellar structure was observed in control sites not treated with CCEF. The bone area ratios of the CCEF-treated sides were larger than those of control sides. These results suggest that the application of CCEF after implant placement may enhance peri-implant osteogenesis, even with functional loading.

Soft tissue closure is a critical factor in preprosthetic surgery and implant placement. In large transverse or vertical bone augmentations, there is often insufficient or very thin mucosa available. Soft tissue dehiscences and bone or implant exposure may result. Based on the application of a periosteal flap, the presented method solves this problem. The flap is prepared in the neighboring area and folded into the corresponding surgical area. It not only provides good soft tissue coverage but also results in soft tissue augmentation. Periosteoplasty has been successfully applied in over 60 patients over the last 2 years.

The aim of this study was to determine the efficacy of a bioresorbable collagen membrane (Bio-Gide) in combination with autogenous bone grafts in the treatment of peri-implant dehiscences, fenestrations, or limited vertical defects. Eighteen titanium dental patients were studied. Autogenous bone was used in all cases to fill the defect and maintain the space underneath the barrier. The collagen membrane was trimmed and adapted to cover the defect in a saddle configuration. The membrane absorbed the blood and easily covered and adhered to the underlying bone. It was not stabilized by any retentive means. Sixteen to 32 months postoperatively, the sites were reentered and the amount of bone regenerated was measured. The results showed significant bone gain (average 87.6%)in the treatment of peri-implant defects with Bio-Gide and autogenous bone.

Congenital absence of multiple teeth and poorly developed alveolar ridges are associated with ectodermal dysplasia. Affected patients often require dental prosthetic treatment during their developmental years. Maxillofacial growth and development in a preadolescent female patient with ectodermal dysplasia following oral rehabilitation with maxillary and mandibular endosseous dental implants is reported. Four maxillary and 4 mandibular implants were successfully integrated and restored at 8 years of age. Growth analysis 12 years later revealed that the implants followed maxillary and mandibular growth displacement. Minor impaction of the maxillary implants was observed, and mandibular implants were affected by the mandibular growth rotation, which led to a change in implant inclination. The treatment outcome is compared to similar previously reported studies and cases.

The success of bone grafting procedures depends largely on the management and integrity of the gingival flaps. Soft tissues aid in the protection of the bone graft, participate in the revascularization of the newly formed hard tissues, and play an important role in the esthetic outcome of the reconstructive phase. Acellular dermal matrix (ADM)is a material obtained from human skin and used in plastic and reconstructive surgery as an allograft. It acts as a bioactive substrate for cell attachment and proliferation. The outcome of the use of ADM as a dressing material to treat flap fenestrations in bone grafting surgery is presented.

Skin overgrowth of auricular implant abutments can be a difficult and frustrating problem, leading to multiple procedures and delaying the placement of a definitive prosthesis. In the present patient, plastic rings or "washers" were employed to successfully deal with this problem. A discussion of the management of peri-implant soft tissues is presented.