A pattern of peri-implantitis affecting middle implants in 3-implant splinted prostheses.

BACKGROUND: Previous investigators have noted an increased risk of crestal bone loss and failure of the middle implant of 3-implant-splinted (3-IS) fixed dental prostheses (FDPs). Possible causes have included ill-fitting prostheses, unhygienic prosthetic contours, and discrepancies in prosthetic platform heights. METHODS & RESULTS: We identified four cases in which the middle implant of a 3-IS multiunit FDP suffered advanced bone loss, ultimately leading to implant removal. While more than one possible risk for implant failure existed in each case, a common thread was that the prosthetic platform of the middle implant for all patients was coronally positioned relative to the corresponding mesial and/or distal implants. CONCLUSIONS: Splinting three adjacent implants into one prosthesis may add risk for a variety of reasons possibly including small differences in the heights of the three prosthetic tables. KEY POINTS: Why are these cases new information? Our observations suggest that discrepancies between implant prosthetic platforms supporting 3-implant splinted, multiunit FDPs may be an added risk factor for middle implant failure. What are the keys to successful management of these cases? It is possible that small differences in apico-coronal implant positioning with 3-implant splinted multiunit FDPs may affect the success of the middle implants. What are the primary limitations to success in these cases? There is limited literature involving precise protocols and long-term outcomes of 3-implant splinted implant restorations. Studies comparing 3-implant splinted FDPs to other configurations are needed.

Anatomically Driven Immediate Implant Placement in the Esthetic Zone: Two Case Reports as Proof of Principle.

Achieving favorable and stable esthetic outcomes with immediate implants used to replace maxillary anterior teeth can be challenging. Osteotomies need to be initiated along the palatal socket wall, and it is often difficult to stabilize initial drilling. An immediate implant was planned for a hopeless maxillary incisor. Using a flapless surgery technique, the tooth was removed and decoronated, and an entry point was made in the root to guide the osteotomy drills. The root was reinserted and stabilized while a precision drill and 2-mm twist drill were used in sequence to drill through the tooth root, establishing the osteotomy location but stopping 3-4 mm short of final depth. The root was then removed, and the final implant bur for a 3.5 × 11.5-mm implant was drilled to depth, engaging the necessary native bone apically. The original tooth crown was then used to prepare and insert a transitional crown. Reinserting the extracted root of a maxillary anterior tooth and using it as a guide for osteotomy preparation is an excellent method to optimally position an immediate implant palatally in the socket wall.

A retrospective report on three implant devices used to restore posterior partial edentulism: overall performance and changes in crestal bone levels.

Three implant designs were used to treat posterior partial edentulism. A total of 799 implants (563 Osseotite, 65 Straumann SLA,171 Endopore SPS) were placed in 345 patients. SPS implants were used in sites with less bone, had shorter lengths, and functioned longer than the threaded implant designs. Comparing implant losses, SPS implants had a higher failure rate (9.3%) compared with Osseotite (4.0%) or SLA (0%) implants. SPS implant losses generally occurred as late failures, while Osseotite losses were early failures. However, among surviving implants, SPS implants had less crestal bone loss at all time intervals compared with both of the threaded implant designs.

Performance of sintered, porous-surfaced, press-fit implants after 10 years of function in the partially edentulous posterior mandible.

This article updates the results of a prospective clinical trial of press-fit, sintered, porous-surfaced dental implants placed in the posterior mandible of partially edentulous patients. Implants used had overall lengths (including transgingival collar regions) of 7 or 9 mm with designed intrabony lengths (lengths of sintered surface in contact with bone) of 6 or 8 mm. Forty-eight implants were placed in 24 patients, the majority of which replaced molar teeth, and the mean crown-to-root ratio was 1.4. Over 10 years of implant function, 2 patients with 3 implants died and 3 patients with 4 implants were lost to follow-up because of infirmity or relocation. The survival and success rates were both 95.5%. Two implants failed; the mean cumulative crestal bone loss (measured from the implant-abutment interface) for the remaining implants was 1.2 mm. Crestal bone loss was not affected by the crown-to-root ratio, prosthesis design, or whether an implant was the most distal unit in a sextant. However, there was a trend for greater crestal bone loss when implants were opposed by implants rather than by natural teeth.

Performance of threaded versus sintered porous-surfaced dental implants using open window or indirect osteotome-mediated sinus elevation: a retrospective report.

BACKGROUND: The purpose of this retrospective report was to evaluate the performance of dental implants placed in a teaching environment in patients requiring maxillary sinus elevation. METHODS: Threaded (acid-washed or sand-blasted acid-etched) and sintered porous-surfaced (SPS) press-fit implants were used. Sinuses were managed using direct (open window) or indirect (osteotome-mediated) techniques. Records were available for 97 implants in 62 patients. Preoperative subantral bone heights were determined from radiographs, primarily panoramic. Of 69 threaded implants used, 40 and 29 were placed using direct (DTH) and indirect (ITH) techniques, respectively. Twenty-eight SPS implants were placed using the indirect technique. Implant failure rates using the Kaplan-Meier method of analysis and cumulative crestal bone loss (the latter based on bone levels seen in the most recent radiographs) were determined for both types of implants. RESULTS: The mean preoperative subantral bone height for DTH implants was 5.0 mm (range, 1 to 12 mm). Preoperative bone heights for ITH implants and SPS implants placed using the indirect approach were 7.2 mm (range, 4 to 12 mm) and 4.2 mm (range, 3 to 6 mm), respectively. Significant differences in preoperative bone height were seen between DTH and ITH implants (P <0.0001) and between ITH and SPS implants (P <0.0001). Average functional times were 18.7 months and 16.3 months for DTH and ITH implants, respectively, whereas the average functional time for SPS implants was 49.9 months. Time in function was significantly greater (P <0.0001) for SPS than DTH and ITH implants. Significant differences in implant length were also seen, with SPS implants significantly shorter than DTH or ITH implants. Three implants failed to integrate, one in each of the three treatment groups, giving initial survival rates of 97.5%, 96.6%, and 96.4% for DTH, ITH, and SPS implants, respectively. Mean cumulative crestal bone loss measurements were 1.84, 1.90, and 0.57 mm for DTH, ITH, and SPS implants, respectively. Bone loss was significantly less with SPS implants than with DTH or ITH implants. A second SPS implant failed after 7 years in function, likely because of prosthetic deficiencies. This late failure reduced the Kaplan-Meier survival rate to 80.4% for the SPS group. CONCLUSION: Results from this teaching clinic suggest that the use of dental implants with sinus elevation procedures is a predictable treatment for the resorbed posterior maxilla.

A pilot study to assess the performance of a partially threaded sintered porous-surfaced dental implant in the dog mandible.

PURPOSE: The purpose of this study was to compare patterns of crestal bone remodeling with 2 sintered porous-surfaced dental implant designs during a 14-month functional period. MATERIALS AND METHODS: Two root-form press-fit dental implants were evaluated in healed extraction sites in dog mandibles. The standard (control) design was a press-fit implant with a 2-mm machined collar; the remainder of the implant had a sintered porous surface. The test or "hybrid" design had 3 coronal machined threads instead of a machined collar; the remainder of the implant had a sintered porous surface. RESULTS: Standardized radiographs indicated significantly less crestal bone loss (0.82 to 0.93 mm versus 1.45 to 1.5 mm) with the hybrid design and a slower approach toward an apparent steady state (12 to 14 months for the hybrid versus 7 months for the standard design). Morphometric assessment of back-scattered scanning electron micrographs confirmed that crestal bone loss was significantly less for the hybrid design on all but the lingual implant aspect. CONCLUSION: The addition of coronal threads to an implant relying on a sintered porous surface geometry for its long-term osseointegration reduced the extent of crestal bone loss compared to a machined collar region.

Threaded versus porous-surfaced implants as anchorage units for orthodontic treatment: three-dimensional finite element analysis of peri-implant bone tissue stresses.

PURPOSE: A 3-dimensional finite element model was developed to investigate the cause of different crestal bone loss patterns observed around sintered porous-surfaced and machined (turned) threaded dental implants used for orthodontic anchorage in a previously reported animal study. MATERIALS AND METHODS: Twenty-noded structural solid elements with parabolic interpolation between nodes were used for modeling the bone-implant interface zone. A 3-N traction force acting between either 2 porous-surfaced or 2 machined threaded implants placed in canine premolar mandibular sites and bone profiles observed at initiation and 22 weeks of orthodontic loading were modeled. RESULTS: Higher maximum stresses in peri-implant bone next to the coronal region of the implants were predicted with the machined threaded implants at both the initial and final time points, with the values 20% greater than those predicted after the 22-week loading period. These values were approximately 200% greater than those predicted for the porous-surfaced implants, for which a more uniform stress distribution was predicted. DISCUSSION: The finite element model results indicated that the observed greater retention of crestal bone next to the porous-surfaced implants was attributable to lower peak stresses developing in crestal peri-implant bone with this design, which decreased the probability of bone loss related to local overstressing and bone microfracture. CONCLUSION: The predicted lower stresses were a result of the more uniform transfer of force from implant to bone with the porous-surfaced implants, which was a consequence of the interlocking of bone and implant possible with this design.

Heterotopic bone formation around sintered porous-surfaced Ti-6Al-4V implants coated with native bone morphogenetic proteins.

PURPOSE: Coating endosseous dental implants with growth factors such as bone morphogenetic proteins (BMPs) may be one way to accelerate and/or enhance the quality of osseointegration. The purpose of this study was to investigate in the murine muscle pouch model whether sintered porous-surfaced titanium alloy implants coated with BMPs would lead to heterotopic bone formation around and within the implant surface geometry. MATERIALS: Porous-surfaced dental implants were coated with partially purified native human BMPs, with or without a carrier of Poloxamer 407 (BASF Corp., Parsippany, NJ), placed in gelatin capsules and implanted into the hindquarter muscles of mice. Mice were euthanized after 28 days. Sections of retrieved specimens were subsequently prepared for morphometric analysis of bone formation using backscatter electron microscopic images. RESULTS: Human BMPs, either with or without the carrier of Poloxamer 407, led to bone formation within and outside of the sintered porous implant surface. When the sintered implant surface region was subdivided into inner and outer halves, similar levels of bone ingrowth and contact were seen in the 2 halves. Evidence of bone formation to the depth of the solid implant core (i.e., the deepest level possible) also was seen. DISCUSSION AND CONCLUSIONS: Sintered porous-surfaced dental implants can be used as substrate for partially purified BMPs in the murine muscle pouch model. With the addition of these osteoinductive factors, the porous implant surface supported bone formation within the surface porosity provided, in some instances, all the way to the solid implant core. The addition of growth factors to a sintered porous surface may be an efficient method for altering locally the healing sequence and quality of bone associated with osseointegration of bone-interfacing implants.

Further data on the predictability of the indirect sinus elevation procedure used with short, sintered, porous-surfaced dental implants.

The object of this report was to provide further data supporting the use of short (primarily 7-mm-long) dental implants with a sintered, porous-surface geometry to treat the posterior maxilla using the indirect, osteotome-mediated, localized sinus elevation procedure. Records were available for 104 Endopore implants (Innova) in 70 patients, for whom the majority of implants had been placed in the location of the maxillary first molar. The mean initial subantral bone height before implant placement was 4.2 mm, with a range of 2 to 6.7 mm, and all implants were placed using hand osteotomes and a graft of bovine hydroxyapatite. After an average time in function of 3.14 years, only two implants had been lost, both as a result of unusual circumstances. It is concluded that the use of short, sintered, porous-surfaced implants and localized indirect sinus elevation is a predictable and minimally invasive approach to manage the posterior maxilla with minimal preoperative subantral bone height.

Osteotome sinus elevation and simultaneous placement of porous-surfaced dental implants: a morphometric study in rabbits.

The objective was to establish a model in rabbits in which to study the healing events associated with localized indirect osteotome-mediated maxillary sinus floor elevation in conjunction with simultaneous placement of sintered porous-surfaced dental implants. On one side of the maxilla of each of 28 rabbits, a sintered porous-surfaced titanium alloy press-fit implant was placed without the use of a bone graft material, while on the collateral side an implant was placed after first adding Bio-Oss graft particles to the osteotomy. Specimens were retrieved for morphometric assessment of bone contact and bone ingrowth of the porous implant surface after 2, 4, 6 and 8 weeks of healing. All implants became osseointegrated by bone ingrowth into the porous implant surface. While the addition of graft particles did not result in a statistically significant increase in the parameters measured, a trend for greater bone contact and particularly bone ingrowth at the apices of the implants was seen as healing time increased. The rabbit maxillary sinus can be used to study healing following placement of sintered porous-surfaced dental implants using the indirect sinus elevation procedure.