The International Journal of Oral & Maxillofacial Implants, 01/1996

One hundred twenty titanium and ceramic root-form and titanium blade implants were placed into 30 dog mandibles. Twenty-four implants in six control dogs (in situ for 5 months) did not receive prostheses. Ninety-six implants in 24 dogs supported prostheses for 6, 12, 18, or 24 months. Computerized morphometry data presented the percent of the implant surface apposed directly by bone. A three-way factorial analysis of variance was used to assess significance. Individual implant means ranged from 0% (mobile implant) to 71% bone adaptation. From these data, two-stage titanium root-form implants were shown to be apposed by more bone than the other five systems, and overall, titanium implant systems were apposed by more bone than ceramic systems. Between 41% and 50% of the surface of integrated ceramic implants were apposed by bone, whereas between 50% and 65% of the surfaces of titanium implants were apposed by bone. Also, two-stage surgery for blade implants appears important for implant success. Furthermore, the use of Nomarski differential illumination appears to be useful for examining the quality of interfacial bone to correlate with the amount of bone quantified by morphometric protocols. Keywords: alumina oxide ceramic, bone, bone contact length, dental implants, fibrous connective tissue, histology, in vivo, mandible, morphometry, scanning electron microscopy, titanium

This study retrospectively evaluated the results of 36 sinus-lift graft augmentations performed to place 66 implant cylinders in the posterior maxilla where vertical bone height was less than ideal. Grafts were accomplished with porous hydroxyapatite (HA) alone, porous HA mixed with autogenous bone removed from the iliac crest, and HA combined with autogenous bone removed from within the mouth. Nineteen core biopsy specimens were taken from different grafts at time intervals ranging from 4 to 36 months from the time of grafting. These cores were evaluated using histomorphometric analysis to yield data comparing volume fractions of bone formation, allowing comparison of different graft materials and healing times. Grafts using porous HA alone on mean produced 16.38% bone by volume after 6 months. After the same healing time, grafts using HA and hip bone on mean produced 19.30% bone by volume compared with an 11.30% bone volume when using HA and bone harvested intraorally. Evaluation of cores taken at 19 and 36 months revealed greater volumes of bone formation. Recommendations based on clinical and histologic results are discussed in detail. Keywords: autogenous, histomorphometric, sinus-lift augmentation, volume fraction

It is critical for the success of endosseous root-form implants that minimal heat is generated in the bone during the drilling of the implant sites. One aspect that has received little emphasis in the literature is the effect of the load placed on the drill during preparation of osteotomies. Temperatures and time were measured while drilling bovine cortical bone at speeds of 1,800 and 2,400 rpm and loads of 1.2 and 2.4 kg. Drilling at a low speed of 1,800 rpm and at a minimal load of 1.2 kg produced the same heat as when the drill speed was increased to 2,400 rpm and the load was increased to 2.4 kg. Independently increasing either the speed or the load caused an increase in temperature in bone. However, increasing both the speed and the load together allowed for more efficient cutting with no significant increase in temperature. Keywords: bone, drilling, heat, implants, pressure, speed

The present study compares the bone response to commercially pure titanium screws with two different degrees of surface roughness. Implants blasted with 25- and 250-µm particles of aluminum oxide were placed in rabbit tibiae after the surface roughness of the implants had been measured. After 4 weeks, there was a significantly higher bone-to-metal contact for implants blasted with 25-µm particles compared to those blasted with 250-µm particles. The present study indicates that a highly increased surface roughness compared to a moderately increased one is a short-term disadvantage for bone tissue. Keywords: histomorphometric evaluation, mechanical evaluation, surface roughness characterization, three dimensional

The purpose of this study is to present new flap designs for the prevention of postoperative gingival recession adjacent to maxillary anterior sites that received dental implants. Nine patients received 10 implants in the maxillary anterior region. Gingival morphotypes and smile lines were evaluated prior to implant placement. Gingival probing depths, clinical attachment levels, and recession were recorded at teeth adjacent to implant sites at the initial exam and 3 months after implant restoration. A minimum of 5 mm of crestal bone width was required for implant placement. The labial flaps for healed ridges and implants placed into sockets were extended to or within 1 to 3 mm beyond the alveolar crest. In two sites, transfer of the implant relationships was made to provide the patients with provisional restorations at the time of second-stage surgery. Four patients had implants placed at the time of tooth removal. In these patients, expanded polytetrafluoroethylene barrier membranes were modified, removing the outer rim of material. The inner portion of the material was placed over the implant and the flaps were sutured, leaving the center part of the material exposed. The purpose of using the barrier in this manner was to protect the clot and subsequent granulation tissue formation during the first 2 weeks of healing. The material was removed 2 weeks after surgery. Six implants were placed into edentulous sites. At second stage surgery, flaps were reflected to the alveolar crest, thereby minimizing the potential for gingival recession. Provisional restorations placed at the time of implant uncovering appeared to support the repositioned gingiva. Changes in probing depth, clinical attachment levels, and recession were not statistically or clinically significant. Results of this pilot project suggest that flap designs minimized recession at teeth next to implant sites. Keywords: barrier membrane, flap design, gingival morphotype, gingival recession, smile line

The aim of the present study was to qualitatively and quantitatively compare the tissue reactions around four different bone substitutes used in orthopedic and craniofacial surgery. Cylinders of two bovine bone substitutes (Endobon and Bio-Oss) and two coral-derived bone substitutes (Pro Osteon 500 and Interpore 500 HA/CC) were implanted into 5-mm bur holes in rabbit tibiae. There was no difference in the amount of newly formed bone around the four biomaterials. Interpore 500 HA/CC resorbed completely, whereas the other three biomaterials did not undergo any detectable biodegradation. Bio-Oss was osseointegrated to a higher degree than the other biomaterials. Material characteristics obtained by diffuse reflectance infrared Fourier transform spectrometry analysis and energy-dispersive spectrometry did not explain the differences in biologic behavior. Keywords: bone substitute, bovine bone, calcium carbonate, coral, material characteristics, material resorption, porous hydroxyapatite

An investigation was conducted to determine whether Dental Prescale, a material that undergoes a graded color-producing chemical reaction when force is applied, could be used to evaluate occlusal load distribution objectively and quantitatively when combined with computer analysis. Ten patients with an implant-supported fixed cantilever prosthesis and a complete conventional maxillary denture were studied. The results indicated that the system can be used to evaluate occlusal load distribution with sufficient reproducibility. However, in its present form, the system is somewhat cumbersome, and its use must now be considered experimental. Further refinement is necessary to allow easier clinical use. Keywords: complete denture, dental implant, occlusal equilibration

Bone marrow transplantation is used with increasing frequency to treat various hematologic diseases, particularly the leukemias. A case involving dental implant therapy in a woman who had undergone successful allogeneic bone marrow transplantation for treatment of chronic myelogenous leukemia is presented to illustrate specific considerations in treatment planning, surgical management, and overall prosthetic rehabilitation. Five mandibular endosseous implants were placed in November 1991 and subsequently restored with a fixed detachable prosthesis. The patient experienced no complications related to the implants or prosthesis during the 3 years after restoration. Keywords: bone marrow transplantation, dental implants, graft-versus-host disease, leukemia

A dental implant covered partially with a porous coating (EndoPore) developed at the University of Toronto was tested. This new implant is a tapered, truncated-cone endosseous root-form implant fabricated from Ti-6Al-4V. It utilizes a powder-sintered porous surface geometry over most of its length to promote three-dimensional bone ingrowth and implant stabilization. In this trial, three implants were placed in the anterior mandibles of 52 patients and were used subsequently as free-standing units to support an overdenture. Much shorter implants, shorter initial healing periods, and simpler surgical techniques than are customary with other implant designs were used. At the time of this report, all patients with implants had passed 3 years of function, and the cumulative implant success rate was 94.8%. Analysis of carefully standardized radiographs revealed a pattern of crestal bone loss similar to earlier published dog data. On a yearly basis, the mean bone loss was 0.43 mm in year 1, 0.17 mm in year 2, and 0.13 mm in year 3. Keywords: EndoPore, overdenture, porous coating, tapered implant

This study compared the effects of metallic, nonmetallic, and sonic instrumentation on titanium abutment surfaces in vitro. Designated test surfaces in each of seven abutments were instrumented either for 25 strokes or 30 seconds, and for 50 strokes or 5 minutes. One abutment served as an untreated control. Scanning electron microscopy photomicrographs were coded and scored by five investigators and designated as smooth (comparable to control) (0), slightly roughened (1), moderately roughened (2), or severely roughened (3). Based on this investigation, the increasing order of surface alteration for each instrumentation was as follows: Implacare Implant Support Steri-Oss Dynatip Columbia 13/14 Sonic scaler Implarette scaler. The Implacare and Implant Support nonmetallic (plastic) scalers appear to be the instruments of choice for debridement of titanium abutment surfaces if preservation of surface integrity is the primary objective. Keywords: implant, instrumentation, maintenance, surface roughness

This paper reports a case in which reconstruction of a midface defect was accomplished by using microvascular surgery with free tissue transfer of the fibula for a 55-year-old man with squamous cell carcinoma in the nasal vestibule and nasal wall. This technique was developed and first used to reconstruct mandibular defects. Using a surgical template during the midface reconstruction can help the surgeon place the graft in a position that will complement the definitive facial prosthesis, as illustrated in this report. Keywords: fibula, free tissue transfer, maxillofacial prosthodontist, microvascular surgery, surgical template

A technique for fabricating a provisional fixed prosthesis for an edentulous arch immediately following abutment connection, termed conversion prosthesis, is described in detail. Advantages of the restoration include the following: it provides a fixed prosthesis immediately following stage 2 surgery with improved function, stability, and distribution of load; it protects the sutured mucosa; it serves as a prototype for the final prosthesis; it can be used as a verification jig; it preserves the original vertical dimension of occlusion; it aids in obtaining and transferring the interocclusal record; it assists long-term patient maintenance; and it reduces treatment visits. The advantages of its use clearly outweigh the disadvantages. Keywords: conversion prosthesis, endosseous implant, fixed prosthesis, provisional prosthesis, transitional prosthesis