Peter K. Moy

Maxillary sinus augmentation: Histomorphometric analysis of graft materials for maxillary sinus floor augmentation

This study used histomorphometric analysis to quantitate the bone composition of four different sinus grafting materials biopsied at the time of implant installation. The study consisted of five patients in whom eight bone biopsies were obtained from seven grafted sites. The grafting materials consisted of hydroxylapatite (HA) granules mixed with cortical chin bone, HA mixed with demineralized bone powder, HA alone, and cortical chin bone alone. Histomorphometry was performed using backscattered scanning electron microscopy images and a computerized image analysis system. The biopsy cores yielded 46 sections from which a total of 255 fields, measuring 2.0 mm x 2.0 mm each, were imaged and analyzed. The biopsy cores contained 44.4% bone after grafting with HA granules and chin bone, 59.4% bone after grafting with chin bone alone, 20.3% bone after grafting with HA granules alone, and 4.6% bone after grafting with HA granules and demineralized bone powder. The small number of biopsies did not permit analysis of statistical significance. However, this study demonstrated the feasibility of correlating mineralized tissue composition of different sinus grafting materials with clinical outcome after dental implant installation.

Pivotal, Randomized, Parallel Evaluation of Recombinant Human Bone Morphogenetic Protein-2/Absorbable Collagen Sponge and Autogenous Bone Graft for Maxillary Sinus Floor Augmentation

PURPOSE The purpose of this prospective study was to evaluate the safety and effectiveness of recombinant human morphogenetic protein-2 (rhBMP-2) on an absorbable collagen sponge (ACS) compared with an autogenous bone graft when used for 2-stage maxillary sinus floor augmentation. The study assessed new bone formation, placement integration, and functional loading after 6 months and long term for 2 years. MATERIALS AND METHODS A total of 160 subjects were randomized, enrolled, and followed from January 1999 to February 2004 at 21 centers in the United States. The subjects with less than 6 mm of native bone height were treated with 1.50 mg/mL rhBMP-2/ACS or with an autograft. The height and density measurements were quantified by computed tomography scans. Core biopsies were obtained at dental implant placement and used for histological analysis. Safety was evaluated by oral examinations, radiographs, serum chemistries, and hematology. RESULTS A significant amount of new bone was formed by 6 months postoperatively in each group. The mean change in bone height in the rhBMP-2/ACS subjects was 7.83 +/- 3.52 mm versus 9.46 +/- 4.11 mm for the bone graft subjects. At 6 months after dental restoration, the induced bone in the rhBMP-2/ACS group was significantly denser than that in the bone graft group. No marked differences were found in the histologic parameters evaluated between the 2 groups. The new bone was comparable to the native bone in density and structure in both groups. The success rate for the rhBMP-2/ACS group was 79% (64 of 81 subjects), and 201 of 251 implants placed in the bone graft group and 199 of 241 implants placed in the rhBMP-2/ACS group were integrated, retained, and functional at 6 months after loading. No adverse events were deemed related to the rhBMP-2/ACS treatment. The autograft group was noted to have a 17% rate of long-term parasthesia, pain, or gait disturbance related to the bone graft harvest. CONCLUSIONS The results of our multicenter, randomized, prospective, clinical trial have shown the effectiveness and safety of rhBMP-2/ACS compared with bone graft for sinus floor augmentation. The studys primary endpoint was exceeded, and the implants placed in rhBMP-2/ACS and bone graft groups performed similarly after functional loading.

Optimum placement of osseointegrated implants

A method was described that includes a stent provided by the restorative dentist indicating optimum implant location. The stent, with imbedded metal bearings, is worn by the patient during tomographic radiographic survey. The tomogram provides a more accurate image of the quantity and quality of the osseous structures. The same template may be used as a surgical stent to aid the surgeon in initial bur placement. Through careful planning and systematic control, the predictable placement of osseointegrated implants can be achieved. With cooperative efforts of restorative dentists and surgeons, more than 400 implants have been successfully placed at University of California, Los Angeles, School of Dentistry.

Nasal defects and osseointegrated implants: UCLA experience

A clinical study of 23 craniofacial implants placed in 11 nasal defects was conducted over a 7-year period. Implant-retained nasal prostheses were fabricated, implant success rate was determined, and the soft tissue responses were recorded at 6-month intervals. No data were gathered on two implants because of patient death. The implant success rate was 71.4% (15/21) but varied significantly by anatomic site. The implant success rate in the glabella was 0% (0/4), whereas the success rate in the anterior nasal floor was 88.1% (15/17). All implant failures occurred within the first year of loading. A five-point scale was used to record the health of the peri-implant soft tissues, and the patients were followed up from 6 to 74 months. The unit of measure was a visit/site, and a unit was assigned for each instance an implant site was evaluated. Evaluations were conducted at 6-month intervals for a total of 76 visit/sites for the study period. The results revealed that 85.5% (65/76) of the visit/sites demonstrated an absence of inflammation; 10.5% (8/76) of the visit/sites demonstrated slight redness; 1.3% (1/76) demonstrated peri-implant red and moist tissues; 2.6% (2/76) demonstrated granulation tissue associated with the implants; and 0% (0/76) demonstrated infection of the peri-implant soft tissues. Severe soft tissue reactions around implants placed in the anterior nasal floor are rare.

Complications of Computer-Aided-Design/Computer-Aided-Machining-Guided (NobelGuide™) Surgical Implant Placement: An Evaluation of Early Clinical Results

PURPOSE The aim of this study was to evaluate early clinical results of computer-aided design (CAD)/computer-aided machining (CAM)-guided surgical implant placement (NobelGuide, Nobel Biocare, Yorba Linda, CA, USA) with focus on surgical and/or prosthetic complications, management, and prevention. MATERIALS AND METHODS Thirteen patients rehabilitated between March 2003 and October 2006 with CAD/CAM-guided dental implants and immediate loading (NobelGuide, Nobel Biocare) were evaluated. The treatment planning and procedures were carried out in accordance to the system protocol. The complications encountered in this case series were classified and assessed according to early (planning and procedural - surgical; prosthetic) and late complications (surgical; prosthetic). RESULTS The prosthetic complications outnumbered surgical complications both in the early and late treatment phases. The main early surgical complication was bony interference that prevented complete seating of the prostheses. Most of the late surgical complications were implant failures with an overall failure rate of 9%. Fracture of the carbon fiber framework prosthesis was the main late prosthetic complication. CONCLUSIONS The NobelGuide system is a reliable treatment modality, but not without its complications. Strict adherence to the system protocol is the key prevention of complications.

AURICULAR PROSTHESES AND OSSEOINTEGRATED IMPLANTS: UCLA EXPERIENCE

A clinical study of 40 craniofacial implants placed in 13 auricular defects was conducted over a 6-year period. Implant-retained prostheses were fabricated, the implant success rate was determined, and the soft tissue responses were recorded at regular intervals. All of the implants became osseointegrated and none demonstrated failure during the study period. A five-point scale was used to record the health of the peri-implant soft tissues and the patients were followed up for up to 69 months. The results were as follows: 55.1% of the visit/sites demonstrated an absence of inflammation; 32.3% of the visit/sites demonstrated slight redness; 4.7% demonstrated red and moist peri-implant tissues; 5.5% demonstrated granulation tissue associated with the implants; and in 2.4% of the implants, infection of the peri-implant soft tissues was noted. Good patient hygiene compliance combined with thin and immobile peri-implant soft tissues resulted in minimal soft tissue complications.

Osseointegrated implants and orbital defects: U.C.L.A. experience

PURPOSE A clinical study of 23 craniofacial implants placed in 8 irradiated and nonirradiated orbital detects was conducted over a 7-year period. MATERIAL AND METHODS Implant-retained orbital prostheses were fabricated, implant success rate was determined, and the soft tissue responses were recorded at 6-month intervals. As a result of patient death, no data were gathered on three implants. A five-point scale was used to record the health of the peri-implant soft tissues and the patients were followed from 9 to 72 months. The unit of measure was a visit/site that was assigned for each instance an implant site was evaluated. Evaluations were conducted at 6-month intervals, and for the study period, there were 80 visit/sites. RESULTS The study revealed that 42.5% (34/80) of the visit/sites demonstrated an absence of inflammation; 23.7% (19/80) of visit/sites demonstrated slight redness; 13.8% (11/80) demonstrated peri-implant red and moist tissues; 6.2% (5/80) demonstrated granulation tissue associated with the implants; and 13.8% (11/80) infection of the peri-implant soft tissues was noted. Implant success rate was 35% (7/20); implant success rate in the nonradiated patients was 37.5% (3/8) and the success rate for radiated patients was 33.3% (4/12). Implants placed in the orbital region demonstrated a high failure rate. Most implant failures occurred late as opposed to early in the study period. CONCLUSION Orbital implants should be placed in patients who understand that long-term success rates may be low and require meticulous hygiene maintenance.

Restoration of irradiated patients using osseointegrated implants: Current perspectives

STATEMENT OF PROBLEM The success rates of osseointegrated implants used to restore patients who were irradiated for head and neck tumors are influenced by radiation-induced changes in the hard and soft tissues. PURPOSE This article examined, by review of the literature, current perspectives on the restoration of irradiated patients using osseointegrated implants. RESULTS In published reports that investigated both intraoral and extraoral applications, irradiation decreased implant success rates and the amount of reduction was dependent on the location within the craniofacial skeleton. The limited number of implants and patients in these studies precludes definitive conclusions regarding the efficacy of placing implants into irradiated tissues. The implants placed into the irradiated anterior mandible have demonstrated an acceptable implant success rate of 94% to 100% with a minimal risk of osteoradionecrosis. The efficacy of implants in the posterior mandible has not been examined. Implant success rates ranged from 69% to 95% in the irradiated maxilla for intraoral applications. Extraoral applications demonstrated excellent implant success rates in the temporal bone (91% to 100%). The rates in the anterior nasal floor have varied from 50% to 100%. The implant success rates in the frontal bone decreased as the length of the studies increased (96% to 33%). The long-term efficacy of implants in the irradiated frontal bone is poor.

Histologic evaluation of human alveolar sockets treated with an artificial bone substitute material.

This study involved a histologic, enzyme histologic, immunohistologic, and three-dimensional microstructure evaluating the extent of osteogenesis and repair in the human alveolar extraction socket achievable with an artificial bone substitute. After tooth extraction in 7 patients, extraction sockets were filled with Mastergraft (15% hydroxyapatite, 85% &bgr;-tricalcium phosphate complex). Radiomicrographs and histologic examinations were performed on samples obtained during dental implant placement procedure. On micro-computed tomography, new bone was observed in all collected samples, and osteogenesis was observed to have taken place around the artificial bone substitute. Histologically, active osteogenesis was found throughout the region observed. Addition of new bone around the Mastergraft was observed, and osteoblast-like cells were present. Cells that had partially invaded the artificial bone included tartrate-resistant acid phosphate-positive and CD34-positive cells. These findings indicate that the Mastergraft artificial bone induced osteogenesis in the jawbone and seemed effective for repairing bone defects.

Mechanical versus biological stability of immediate and delayed implant placement using resonance frequency analysis.

PURPOSE The purpose was to objectively measure the stability of immediately placed implants compared with implants placed at healed sites using implant stability quotient (ISQ) values obtained by resonance frequency analysis. MATERIALS AND METHODS Data were collected from 137 Nobel Replace Tapered Groovy Implants placed in 85 patients 19 to 93 years old. All implants were placed by the same surgeon from May 2007 to October 2011. Forty-one implants were placed immediately after extraction with MasterGraft bone grafting material and 96 were placed in healed sites with no grafting material. ISQ values obtained by the Osstell ISQ System were recorded at the time of implant placement and at a subsequent follow-up appointment (T2). T2 was split into 2- to 3-month and 4- to 6-month groups depending on when their follow-up ISQ values were obtained. Data were analyzed using simple linear regression. RESULTS Implants placed in healed sites had higher average ISQ values at implant placement compared with immediately placed implants; however, mean ISQ values in the 2 immediate implant groups exceeded the ISQ threshold of 65. Immediately placed implants in the 2- to 3-month and 4- to 6-month groups had average ISQ values of 65.60 and 68.65, respectively, whereas implants placed in healed sites had averages of 76.73 (2- to 3-month group) and 71.23 (4- to 6-month group). These differences were statistically significant (P < .05). At subsequent follow-up appointments, implants placed in healed sites had higher mean ISQ values. Implants in healed sites had ISQ averages of 79.58 (2- to 3-month group) and 77.31 (4- to 6-month group), whereas immediately placed implants had averages of 73.88 and 70.14. These differences were statistically significant (P < .05). Moreover, these mean ISQ values in immediate implants exceeded the ISQ threshold of 65. CONCLUSION Although mean ISQ values of immediately placed implants are lower than those of delayed implants at implant placement and follow-up appointments, immediate implant mean ISQ values consistently remain higher than the clinically successful ISQ threshold of 65 throughout the osseointegration process. These results support the immediate placement of implants in extraction sockets under favorable conditions.