The International Journal of Oral & Maxillofacial Implants, 03/2000

The bone anchorage components of commercially available oral implant systems differ in surface roughness by at least sixfold. Correct reporting of the surface roughness of implant systems is important, since one cannot exclude the possibility that surface roughness will influence clinical results. However, many confusing statements are found in the literature when the surface topography of implants is described. Different measuring instruments and techniques strongly influence the outcome of a topographic characterization. Furthermore, a screw-type design introduces problems for most measuring instruments. Without a standard procedure, it is generally impossible to compare values from one study with another. The aim of the present study was to suggest standards for topographic evaluation of oral implants in terms of measuring equipment, filtering process, and selection of parameters. It is suggested that the measuring instrument be able to measure all parts of a threaded implant if the investigation relates to such a design. Preferably, 3-dimensional measurements should be performed. On screw-type implants, tops, valleys, and flanks should be evaluated. At least 3 samples in a batch should be evaluated, filter size must be specified, and at least one of each height, spatial, and hybrid parameter should be presented. Parole chiave: dental implants, laboratory techniques and procedures, surface properties

Although dental implants continue to provide consistent and predictable treatment options for most patients, some people with uncontrolled systemic disease may be denied implant treatment. Diabetes is one such disease. According to the U.S. Centers for Disease Control and Prevention, diabetes is a leading cause of blindness, kidney failure, and amputations of the lower extremities. These complications result from microvascular disturbances associated with diabetes. The effect of diabetes on the healing of titanium implants has not been well established. In this study of 32 rats, diabetes was induced in 16 animals by injection of streptozotocin (65 mg/kg); the remaining 16 animals served as controls. Titanium alloy implants were placed in the tibiae of all 32 rats using standard surgical techniques. Implants healed for 14 days. Blood samples were obtained for serum glucose, osteocalcin, and alkaline phosphatase analyses. Implants were retrieved and processed for histomorphometric analyses. Three quantities were measured using light microscopy, video capture, and computer analysis: percent osseointegration (ie, linear bone interface), associated bone volume percent, and contact frequency. Diabetic animals demonstrated significantly less osseointegration than controls. However, bone volume percent in diabetic animals was about 4 times greater than controls. Biochemical analyses were mixed; diabetic animals demonstrated increased serum osteocalcin levels compared to controls but decreased alkaline phosphatase. Based on the results of this study, it was concluded that the bone response associated with titanium alloy implants in the tibiae of diabetic rats is uniquely different from controls. Parole chiave: alkaline phosphatase, bone, bone histomorphometry, diabetes, implants, osseointegration, osteocalcin, titanium alloy

This study examined the effects of different treatments (polished, electropolished, and grit-blasted) on the surface morphology and chemistry of commercially pure titanium and titanium-6% aluminum-4% vanadium. The structure and composition of the surfaces were evaluated using scanning electron microscopy, atomic force microscopy, energy dispersive spectroscopy, Auger microprobe analysis, and x-ray photoelectron spectroscopy. Surface roughness values at large scales were nearly identical for grit-blasted and electropolished samples, while at smaller scales, electropolished and polished samples had nearly identical quantitative roughness values. The surface oxide compositions were found to be primarily titanium dioxide on both materials for all surface treatments. No vanadium was seen with either x-ray photoelectron spectroscopy or Auger microprobe analysis for the alloy, indicating a possible surface depletion. Calcium was present on the grit-blasted samples, and calcium and chlorine were detected on the electropolished samples. Parole chiave: characterization, dental implants, surface properties, titanium

The aim of this experimental study was to evaluate the use of autogenous bone harvested during preparation of implant sites in combination with resorbable membranes for vertical ridge augmentation under 2 different defect site conditions. Combined vertical/horizontal alveolar bone defects were created by experimentally induced periodontal infections around all premolar teeth in the mandibles of 3 dogs (group 1). In another 3 dogs, fresh surgical defects were created after extraction of all premolar teeth in the mandibles (group 2). In all dogs, 2 implants were placed on each side of the mandible into the defect areas. One implant on each side of the mandible received augmentation with autogenous bone particles, and both implants on one side of the mandible were covered with polylactic acid membranes. After 5 months, the material was evaluated histologically. There was a small but significant increase in bone regeneration in the defects augmented with bone particles with and without membrane coverage in group 1. In group 2, no significant difference was seen between the controls and the augmented sites. The major limiting effect for bone regeneration appeared to be insufficient stability of the bone material to withstand the overlying soft tissue pressure. It was concluded that the placement of autogenous bone particles, either with or without membrane coverage, had little effect on the regeneration of peri-implant bone defects. Parole chiave: artificial membranes, bone regeneration, bone transplantation, dental implants, guided tissue regeneration, membranes, polymers

This clinical study reports on the results of a new method in the treatment of peri-implantitis. The surfaces of 24 plasma flame-sprayed cylindric implants in 17 patients who were diagnosed with peri-implantitis were decontaminated with a combination of toluidine blue (100 µg/mL) and laser irradiation at a wavelength of 906 nm. Bone defects were filled with autogenous bone using e-PTFE membranes for retention of the grafting material. Premature membrane exposure occurred in all patients after an average of 3 weeks (± 10 days), which required immediate removal of the exposed membrane in 1 patient. Since the soft tissue showed minimal signs of inflammation, the membranes were left in situ for another 6 weeks in all other patients. The mean radiographic peri-implant bone gain was 2 mm ± 1.90 mm after 9.5 months (maxilla 2.5 mm ± 2.38 mm; mandible 1.9 mm ± 1.87 mm). Two implants around which the initial bone defect had already reached the basket had to be removed after 10 months and 35 months, respectively, despite radiographic evidence of improvement of the peri-implant defect. The longer the membrane stayed in situ, the more bone was gained, as long as the membrane was covered by soft tissue (P = .01). However, the longer an exposed membrane was left in place, the smaller the resultant bone gain (P = .0001). Therefore, despite the absence of clinical signs of inflammation, exposed membranes should be removed immediately. The short-term results of this study corroborate the efficacy of the applied treatment method in prolonging the service time of dental implants involved with peri-implantitis. Parole chiave: autogenous bone, endosseous dental implantation, guided tissue regeneration, laser therapy

A prospective study was conducted in which 21 patients received a mandibular implant-supported overdenture. Eighty-four ITI screw-type implants were placed in the interforaminal area of the mental symphysis (4 implants per patient). Immediately after implant placement, a U-shaped gold or titanium bar was fabricated and implants were loaded with an implant-retained overdenture. Of 21 patients treated, 19 were followed for a minimum of 25 months to a maximum of 60 months, with a mean follow-up of 37 months. Two patients dropped out during the follow-up. The overall failure rate of implants (according to Albrektsson criteria) was 4% (3/76 implants), but all implants, bars, and prostheses remained in function. Results from this study demonstrated that the success rate for immediately loaded mandibular implants is similar to that obtained in cases of delayed loading, after osseointegration has taken place. This method shortens dental rehabilitation time with relevant satisfaction for patients. Parole chiave: complete overdentures, dental implants, edentulous jaw, immediate implant loading, mandibular prosthesis, osseointegration, prospective study

Long-term studies have documented the successful treatment of edentulous and partially edentulous patients with titanium implants. However, the inability to identify some non-osseointegrated implants before occlusal loading is costly to practitioners and patients. This study followed all patients (n = 40) who had implants placed over a 6-month period. The Periotest instrument was used at Stage II surgery, final impression, prosthesis placement, and 6 and 12 months after occlusal loading to quantify mobility/lack of mobility of implants with conventional 1-piece temporary healing abutments in place. The positive predictive value was 64%. The Periotest instrument was able to identify non-integrated implants only when measured at Stage II surgery and 12 months after occlusal loading, 64% of the time. However, Periotest values recorded at Stage II surgery are not valid predictors of non-osseointegrated implants 12 months post-occlusal loading. Parole chiave: dental prosthesis, endosseous dental implantation, osseointegration, sensitivity and specificity

Fifty-nine commercially pure titanium implants in 59 subjects were compared with internal control teeth for 3 years. Nineteen coated implants of identical design were placed in 17 of the subjects and compared with the titanium implants. Demographic data, microbial DNA, aspartate aminotransferase levels, Plaque Index, width of adjacent keratinized tissue, probing depths, bleeding on probing, relative attachment levels, mobility, and radiographic bone height were studied. The only statistically significant changes over time were improved plaque scores in the subjects and slight bone loss around the implants. There were no differences between the 2 types of implants. Mobility was less and probing depth and bleeding on probing were greater in the implant sites than in the control sites. Parole chiave: dental implants, dental radiography, oral diagnosis, patient satisfaction, surface properties

Rehabilitation of atrophied edentulous arches with endosseous implants in the posterior regions is often associated with anatomic problems such as jaw shape and location of the mental loop, mandibular canal, and maxillary sinuses. The purpose of this investigation was to modify the method for implant placement in the posterior part of the jaws to extend fixed implant-connected prostheses further distally, and to reduce the length of cantilevers in complete-arch prostheses without transpositioning the mandibular nerve or performing bone grafting in the maxilla. Forty-seven consecutive patients were treated with implants (25 patients/36 mandibular implants, 22 patients/30 maxillary implants) placed in tilted positions. They were followed a mean of 40 months (mandibles) and 53 months (maxillae). In the mandible, implants close to the mental foramina were tilted posteriorly approximately 25 to 35 degrees. In the maxilla, the posterior implants were placed close to and parallel with the sinus walls and were titled anteriorly/posteriorly approximately 30 to 35 degrees. Patients gained a mean distance of 6.5 mm of prosthesis support in the mandible and 9.3 mm in the maxilla, as a result of implant tilting. There were no implant failures in mandibles. The cumulative success rates in the maxilla at 5 years were 98% for tilted implants and 93% for non-tilted implants. Paresthesias of the mental nerve were observed on 4 sides during the first 2 to 3 weeks after implant placement. Analysis of the load distribution in one mandibular case showed no significant difference between tilted and the non-tilted implants, and the improved prosthesis support was confirmed. Satisfactory medium-term results concerning osseointegration and significant extension of prosthesis support show that the method can be recommended. This technique may allow for longer implants to be placed with improved bone anchorage. Parole chiave: edentulous jaw, endosseous dental implantation, implant-supported dental prosthesis, maxillary sinus, mandibular nerve

This article presents a technique for soft tissue reconstruction and covering defects associated with maxillary implant-supported restorations. A pedicle subepithelial connective tissue flap is prepared from the palatal mucosa near the area to be treated and is displaced into the receptor site. The donor site remains primarily covered. An increase in soft tissue volume is achieved at the receptor site, which is advantageous for various reasons. The pedicle graft has been used for different indications: closure of the alveolus after immediate implant placement, papilla reconstruction, defect and dehiscence repair, and multiple-layer closures after bone grafting and treatment of peri-implantitis. Over a 32-month period, 103 patients were treated with this method. Partial flap necrosis occurred in only 2 patients. All other patients showed significant improvement over the preoperative condition. Parole chiave: endosseous dental implantation, gingivoplasty, guided tissue regeneration, pedicle graft, surgical flaps

Spontaneous alveolar ridge growth in the posterior region of the mandible following placement of endosseous implants is reported. The study included 27 patients with totally edentulous mandibles and fixed prostheses supported by osseointegrated implants placed between the mental foramina. In 5 patients, an increase in the height of the alveolar crest was observed in the molar region; the increase ranged from 3.3% to 8.6%. This osseous proliferation may be a physiologic response to stress distribution in the molar region. Parole chiave: alveolar process, endosseous dental implantation, mandible, osteogenesis

The influence of experimental occlusal overload on peri-implantitis in monkeys (Macaca fascicularis) has been examined to explain the pathology of the disease that develops in the tissue around osseointegrated implants. In the first article of this series, it was reported that bone resorption was not observed around implants when occlusal trauma was produced by a superstructure that was in supraocclusal contact with an excess occlusal height of approximately 100 µm, provided there was no inflammation in the peri-implant tissue. In the second part of the study, experimental inflammation was created in the peri-implant tissue, and occlusal overload was produced by a superstructure with an excess occlusal height of 100 µm. Notable bone resorption was observed around the implant with the passage of time. These results suggested that, in addition to the control of inflammation in peri-implant tissue, traumatic occlusion may play a role in bone breakdown around the implant. In the present study, while the peri-implant tissue was kept in an inflammation-free state, bone level changes around the implants were investigated when various levels of traumatic force were exerted. The supraoccluding prostheses were defined as excessively high by 100 µm, 180 µm, and 250 µm, respectively. The heights were determined with an image analysis device, and the bone responses around the implants induced by the traumatic forces were investigated. The results showed that bone resorption around implants tended to increase with 180 µm or more excessive height of the superstructure. This suggests that the threshold of excessive height of the superstructures at which peri-implant tissue breakdown may start is approximately 180 µm. It is also suggested that there is a possibility of bone resorption around the implants caused by excess occlusal trauma, even when there is no inflammation in peri-implant tissue. Parole chiave: animal study, bone resorption, comparative histology, endosseous dental implantation

The placement of an implant immediately after tooth extraction may have the following advantages: reduction in morbidity, treatment time, and treatment costs; preservation of the residual ridge width and height; optimal esthetic result; and easier definition of implant position. The aim of the present study was the presentation of a human clinical and histologic report involving a nonsubmerged implant placed in a mandibular postextraction site and removed because of persistent pain. At low-power magnification, it was possible to see that newly formed bone with wide osteocyte lacunae was present around the implant. A 1.5-mm sulcular epithelium was visible on one side of the implant, with a 0.5-mm epithelial attachment. The thickness of the supracrestal connective tissue was 3.2 mm. This connective tissue was dense, had few cells, was well vascularized, and showed no evidence of an inflammatory infiltrate. Under polarized light, it was possible to observe that the connective fibers were arranged perpendicular to the implant surface and that these fibers became parallel near the implant. These results show that human immediate postextraction implants can have a high percentage of bone-implant contact. Parole chiave: connective tissue, endosseous dental implantation, epithelium

This case report presents a clinical, radiographic, and histologic evaluation of 2 non-adjacent, hydroxyapatite-coated, root-form implants retrieved from the maxillary canine area of a patient after 7 years in function. Clinical examination revealed immobile implants with no sign of pathosis. Radiographic examination indicated close proximity of the bone to the implant surface without evidence of radiolucency. Histologically, the 2 implants appeared to be well integrated with the surrounding bone; 84% of the surface of the first implant and 79% of the surface of the second implant had close bone apposition at the interface. There was no evidence of dissolution of the hydroxyapatite coating. The bone appeared to be in immediate contact with the coating. These observations suggest that a particular hydroxyapatite coating on root-form implants can resist degradation during long-term function. Parole chiave: dental implants, histology, hydroxyapatite, osseointegration, radiography