A possible "rescue" procedure for dental implants with a textured surface geometry: a case report.

Dental implants with textured surfaces are a valuable adjunct in restoring edentulous sites of poor bone quality and quantity, but on occasion may become denuded of bone and require "rescue." We report here the successful management of an intrabony crater affecting a single porous-surfaced dental implant using a combination of citric acid decontamination and grafting with freeze-dried, demineralized allograft covered with a barrier of calcium sulfate.

Managing the posterior mandible of partially edentulous patients with short, porous-surfaced dental implants: early data from a clinical trial.

Forty-eight Endopore dental implants were placed in the posterior mandibles of 24 partially edentulous patients. Seventeen of these implants replaced premolar teeth, while 31 replaced molars. Only 7-mm and 9-mm implants were used, and the majority of prosthetic restorations (83%) were single crowns. After a mean functional time of 32.6 months (range, 8.2 to 50.3 months), the implant survival rate was 100% and assessment of available radiographic data showed minimal to no crestal bone loss.

A prospective human clinical trial of Endopore dental implants in restoring the partially edentulous maxilla using fixed prostheses.

This is the first report of a group of 50 partially edentulous patients who received a total of 151 Endopore dental implants in the maxilla. A mean implant length of 8.7 mm was used, and 76.8% of implants were placed in the posterior maxilla. At re-entry, all implants appeared to be osseointegrated and were used to support fixed prostheses. Approximately half of the crowns (57%) in these prostheses were splinted to one another, while the remainder (43%) were not. At the time of this report, the mean functional time was 34.6 months and the cumulative survival rate was 97.3% (4 implants had failed). Analysis of carefully standardized sequential radiographs indicated no significant changes in mean crestal bone levels between baseline and any of the examination times (after 6 months, 1 year, and 2 years in function). There were no detectable correlations between crestal bone loss and the factors implant length (7, 9, or 12 mm); implant diameter (3.5, 4.1, or 5.0 mm); implant position anteriorly or posteriorly in the maxilla; or whether or not the implant-supported crowns were splinted.

Simplifying management of the posterior maxilla using short, porous-surfaced dental implants and simultaneous indirect sinus elevation.

This article describes the use of short, porous-surfaced root-form dental implants and an indirect, simultaneous, osteotome-mediated sinus elevation procedure to restore the posterior maxilla when as little as 3 mm of bone remain below the sinus floor. Results with 16 patients who are part of an ongoing prospective clinical trial using the Endopore implant show 100% success (using established criteria) with a mean implant length of 6.9 mm and a mean functional time of 11.1 months. This treatment approach greatly simplifies the management of the posterior maxilla with minimal bone height below the sinus floor.

Five- to six-year results of a prospective clinical trial using the ENDOPORE dental implant and a mandibular overdenture.

This report is an update on a group of 46 clinical trial patients who each received 3 free-standing Endopore dental implants placed using a 2-stage surgical approach in the anterior mandible. After an initial healing interval of 10 weeks, the implants were used in each case to retain an over-denture, and at the time of the report, all patients had passed 5 years of continuous function. The 5-year cumulative "survival" rate based on a life table analysis was 93.4% and this remained unchanged after 6 years. The 5-year "success rate" was 83.3% when assessed qualitatively with the published criteria of others using a four-field table analysis categorizing every implant in the study as one of "Grade 1 Success", "survival", "unaccounted for" or "failure". Modified periodontal parameters verified continued peri-implant soft tissue health. No implant still in function had more than 1.8 mm cumulative bone loss during the first 5 years of function. These results provide clear evidence that Endopore implants despite their short lengths function at least as well as other dental implant designs used in much longer lengths.

Use of a tapered, porous-surfaced dental implant in combination with osteotomes to restore edentulism in the difficult maxilla.

The maxilla is the more difficult arch to restore with endosseous dental implants because of hurdles such as low bone density, narrow buccopalatal width, minimal bone height, and proximity to the maxillary sinus. In this article, a technique to resolve all of these problems using a short, tapered, porous-surfaced implant and a placement protocol using hand osteotomes rather than surgical burs is presented.

The Endopore implant-enhanced osseointegration with a sintered porous-surfaced design.

The Endopore implant provides a novel method for reliable fixation of endosseous dental implants within the bone. Through the use of a porous-surfaced zone formed by sintering Ti alloy particles of the appropriate size and under appropriate processing conditions to a sold Ti alloy core of desired shape (tapered truncated cone), an implant is now available that can be placed using a relatively simple surgical procedure using either surgical burs or hand osteotomes. Of even greater value is the suitability of this implant design for treatment of cases that because of minimal bone height cannot be treated routinely using other currently-available implants. The high success rates experienced with significantly shorter implant lengths compared with other designs indicate the appropriateness of this system for difficult-to-treat cases. The Endopore system represents the next generation of endosseous dental implants characterized by uncomplicated and reliable treatment for a wider range of dentally-compromised patients. Its history is founded on extensive and fully-documented research at the human preclinical stage as well as human use experiences. The results during the past nine years have confirmed the high expectations that those early studies suggested.

Use of the Endopore dental implant to restore single teeth in the maxilla: protocol and early results.

This report outlines the experimental, surgical, and prosthodontic protocols for a prospective clinical trial using the Endopore dental implant to replace single maxillary teeth. Twenty patients (10 male, 10 female) ranging in age from 30 to 60 years each received one implant (mean length 10.1 mm), which, after an initial healing period of 4 months, was restored with a single crown. Records collected included radiographs, Periotest mobility measurements, supragingival Plaque Index, and an assessment of peri-implant soft tissue health using pocket probing depths, sulcular bleeding following probing, and probing attachment levels. Radiographs were exposed at predetermined intervals following crown placement (1 and 6 months, and then yearly) in a standardized procedure using a specialized filmholder that attaches to each implant after removal of the crown. At the time of this preliminary report, all of the 20 implants placed had been uncovered and were in function; 16 of the implants had been in function for 6 months or more, 14 had passed 1 year of function, and 3 had passed the 2-year function point. There have been no failures to date.

Regulation of osteopontin expression in osteoblasts.

Osteopontin (OPN) is a prominent bone matrix protein that is synthesized by osteoblastic cells. To elucidate the function of OPN in bone we studied the regulated expression of the rat OPN protein during bone formation in vivo and in vitro. OPN mRNA is expressed by preosteoblastic cells early in bone formation, but the highest expression is observed in mature osteoblasts at sites of bone remodelling. A low-phosphorylated, 55-kDa form of OPN is produced by the preosteoblastic cells, whereas osteoblasts produce a highly phosphorylated, 44-kDa protein; the two forms of OPN corresponding to pp69 and pp62 in transformed rat cells. The synthesis of the 55-kDa OPN correlates with the formation of a 'cement' matrix that is synthesized prior to bone deposition, whereas the 44-kDa OPN synthesized by osteoblasts associates rapidly with hydroxyapatite, possibly regulating crystal growth, and may also provide a substratum for osteoclast attachment. Expression of OPN mRNA is upregulated by growth and differentiation factors (PDGF, EGF, TGF-beta and BMP-7/OP-1) and by mechanical stress, which promote bone formation, as well as by osteotropic hormones (retinoic acid and vitamin D3), which can promote bone resorption and remodelling. However, OPN mRNA is down-regulated by bisphosphonates, which abrogate bone resorption. Regulation of OPN expression is, therefore, consistent with a multiplicity of functions for OPN that involve specific structural motifs in both the synthesis and resorption of bone.

Temporal changes in matrix protein synthesis and mRNA expression during mineralized tissue formation by adult rat bone marrow cells in culture.

To characterize the bone-like tissue produced by rat bone marrow cells (RBMC) from young adult femurs, the synthesis of bone proteins and the expression of their mRNA were studied in vitro. RBMC plated at a density of 5 x 10(3) cells/cm2 and grown in the presence of 10(-8) M dexamethasone (Dex) and 10 mM beta-glycerophosphate (beta-GP) produced mineralized bone nodules, which were first evident at day 3 and increased markedly to day 13. However, in the absence of dexamethasone, few mineralized nodules were observed. The formation of mineralized nodules was reflected by the uptake of 45Ca, which also increased markedly to day 13. Analysis of bone protein expression by Northern and slot-blot hybridizations revealed an increase in mRNA levels of collagen type I (Col I), osteonectin/SPARC (ON), alkaline phosphatase (ALP), osteopontin (OPN), bone sialoprotein (BSP), and osteocalcin (OC) during the formation of mineralized nodules. Whereas the Col I, ON, ALP, and OPN mRNAs were expressed before the formation of mineralized nodules was evident and were also expressed at various levels in the absence of Dex, the expression of BSP and OC mRNA was induced in the bone-forming cultures. The expression of BSP mRNA was correlated temporally with bone tissue formation, reaching maximal levels on day 16. In contrast, OC mRNA was expressed later and, following induction, increased over the 28 day culture period. Production of matrix proteins during the rapid formation of the bone tissue appeared to reflect the levels of the respective mRNAs. However, whereas some of the collagen and almost all of the SPARC were secreted into the culture medium, virtually all of the OPN and most of the BSP were extracted from the mineralized tissue matrix with EDTA. Some OPN and BSP were present in the medium, especially early in the culture, and a significant amount of BSP was also found associated with the collagenous tissue matrix. These studies point to the importance of Col I, ALP, OPN, and BSP, but not ON or OC, in the initial formation of bone tissue.

Expression of bone matrix proteins associated with mineralized tissue formation by adult rat bone marrow cells in vitro: inductive effects of dexamethasone on the osteoblastic phenotype.

The nature and tissue distribution of non-collagenous bone proteins synthesized by adult rat bone marrow cells, induced to differentiate in the presence of dexamethasone (DEX) and beta-glycerophosphate (beta-GP), was studied in vitro to determine the potential role of these proteins in bone formation. Northern hybridization analysis revealed a strong induction of bone sialoprotein (BSP) and osteocalcin in DEX-treated cultures, whereas the constitutive expression of secreted phosphoprotein I (SPP-1), type I collagen, SPARC, and alkaline phosphatase was stimulated 6-, 5-, 3-, and 2.5-told, respectively. Metabolic labeling of proteins showed that the sialoproteins (SPP-1 and BSP) were mostly secreted into the culture medium in the non-mineralizing (-beta-GP) cultures, but were the predominant non-collagenous proteins associated with the hydroxyapatite of the bone nodules in mineralizing cultures (+ beta-GP). Extraction of the tissue matrix with 4 M GuHCl and digestion of the demineralized tissue matrix with bacterial collagenase revealed that some BSP was also associated non-covalently and covalently with the collagenous matrix. SPP-1 was present in two distinct, 44 kDa and 55 kDa, forms in the conditioned medium of all cultures and was preferentially associated with the hydroxyapatite in the mineralizing cultures. In comparison, SPARC was abundant in culture media but could not be detected in de-mineralizing extracts of the mineralized tissue. Radiolabeling with [35SO4] demonstrated that both SPP-1 and BSP synthesized by bone cells are sulfated, and that a 35 kDa protein and some proteoglycan were covalently associated with the collagenous matrix in +DEX cultures. Labeling with [32PO4] was essentially confined to the sialoproteins; the 44 kDa SPP-1 incorporating significantly more [32PO4] than the 55 kDa SPP-1 and the BSP. These studies demonstrate that BSP and osteocalcin are only expressed in differentiated osteoblasts and that most of the major non-collagenous bone proteins associate with the bone mineral. However, some novel proteins together with some of the BSP are associated with the collagenous matrix where they can influence hydroxyapatite formation.

Sulphation of secreted phosphoprotein I (SPPI, osteopontin) is associated with mineralized tissue formation.

Secreted phosphoprotein I (SPPI) is a prominent structural protein in mineralized connective tissues. Rat bone cells in culture produce several forms of SPPI that differ in post-translational modifications such as phosphorylation and sulphation. To determine the significance of protein sulphation in bone formation, the synthesis of SPPI was studied in vitro using rat bone marrow cells (RBMC) which form bone-like tissue when grown in the presence of dexamethasone (Dex) and beta-glycerophosphate (beta-GP). In the presence of 10(-7) M Dex SPPI expression was stimulated 4-5-fold. Radiolabelling multilayered RBMCs for 48 h with [35S]-methionine, Na2[35SO4], or Na3[32PO4] revealed that two major phosphorylated forms of SPPI were secreted into the culture medium: a highly phosphorylated form migrating at 44 kDa on 15% SDS-PAGE and a less phosphorylated 55 kDa form. In the mineralized tissue formed in the presence of Dex and beta-GP, both forms of SPPI, in addition to proteoglycans and a 67 kDa protein, incorporated significant amounts of [35SO4]. Sulphation of SPPI was not observed in the absence of mineral formation, indicating that the sulphation of SPPI is closely associated with mineralization and that it can be used as a sensitive and specific marker for the osteoblastic phenotype.