Zeev Ormianer

Long-Term Results of Implants Immediately Placed Into Extraction Sockets Grafted With β-Tricalcium Phosphate: A Retrospective Study

PURPOSE The aim of this 10 year retrospective study was to evaluate the crestal bone loss around immediate implant placed in tricalcium phosphate (TCP) grafted extraction sockets MATERIALS AND METHODS Data were collected from files of 58 patients (33 females, 25 males, average age 54.78 years) undergoing immediate implant placement into fresh extraction socket with or without the use of TCP (Cerasorb, Curasan AG, Kleinostheim, Germany) grafting. After implant placement, horizontal gaps larger than 1.5 mm between the implant surface and the bony plate were grafted with TCP without the use of a membrane, while smaller gaps were not grafted. Two hundred fifty-four implants were inserted: 79 were placed immediately with the use of β-TCP as grafting material (group A), 175 were placed in healed extraction sites, with 61 implants placed with the use of β-TCP graft material (group B), and 114 implants were placed without any grafting material (group C). Bone loss recordings were performed using periapical radiography. Measurements were performed from the neck of the implant to level of the surrounding bone in the vertical dimension. RESULTS No implant was lost during the follow-up period. Statistical analysis showed no correlation between implant placement timing (delayed or immediate), the use of bone graft, and extent of bone loss. CONCLUSION The use of TCP (Cerasorb) as a grafting material during immediate implant placement allowed no bone loss in 72.1% of the implants, which was very similar to the nongrafted cases for which implants were placed in favorable conditions.

Retrospective clinical evaluation of tapered implants: 10-year follow-up of delayed and immediate placement of maxillary implants.

Objectives:To retrospectively evaluate the clinical outcome of tapered, multithreaded implants (Tapered Screw-Vent MTX; Zimmer Dental, Inc, Carlsbad, CA) with an emphasis on periimplant crestal bone status around those placed delayed and immediately in the posterior and anterior maxilla. Methods:Chart reviews were performed on 46 patients who had been treated with 173 implants replacing one or more missing and/or unsalvageable teeth in the maxilla. Implant placement and loading was either immediate or delayed. Marginal bone changes were calculated using standardized radiographs taken at implant placement and during annual follow-up. Results:After a mean follow-up of 119 to 121 months, implant survival rate was 99%, and implant success rate was 97%. No discernable bone loss was evident in 85.5% of the surviving implants. Crestal bone loss was observed in 14.5% of all surviving implants: 38.5% of implants immediately loaded and 29.9% of implants with delayed loading. Twenty-one implants exhibited 1 mm of bone loss, 3 implants lost 2 mm, and 1 implant lost 3 mm. Low-density maxillary jawbone and more extensive bone remodeling required around implants immediately placed into extraction sockets were the probable causes of observed bone loss in this study. Conclusions:Implants exhibited excellent long-term outcomes with little or no bone loss.

A 10-Year Retrospective Clinical Evaluation of Immediately Loaded Tapered Maxillary Implants

PURPOSE The aim of this study was to compare the effects of immediate loading (IL) and delayed loading (DL) on peri-implant crestal bone loss around maxillary implants after long-term functioning. MATERIALS AND METHODS A retrospective chart review was conducted to assess the outcomes of 110 tapered, multithreaded implants placed for the treatment of one or more missing and/or unsalvageable teeth in the maxilla of 23 patients. Implants were assigned to either the DL or IL database according to loading time. Marginal bone changes were calculated using standardized radiographs taken at implant placement (baseline) and during annual follow-ups. RESULTS One implant failed in the DL group. After a mean follow-up of 111 months in the DL group and 119 months in the IL group, cumulative implant survival was 99.09% (DL = 98.11%, IL = 100%). No observable bone loss was evident in 83.49% of the surviving implants. Cumulative success rates were 100% for the IL group and 98.11% for the DL group. CONCLUSIONS Immediately loaded maxillary implants showed long-term results comparable to delayed loaded maxillary implants.

Stress and strain patterns of 1-piece and 2-piece implant systems in bone: a 3-dimensional finite element analysis.

Statement of Problem: The transition from implant to abutment is solid in 1-piece (1P) and broken in 2-piece (2P) implant designs. This difference may affect occlusal load distribution and marginal bone response. Purpose: To determine whether 1P and 2P implants with equivalent geometries exhibited stresses and strains differently under applied loading conditions. Materials and Methods: Design software simulated 1P and 2P implants restored with metal copings and embedded in 3 cylindrical bone block models that varied in dimensions, density, and percentage of bone-to-implant contact. Three-dimensional, finite element analysis simulated occlusal loading. Experiments evaluated stresses and strains relative to implant design and (1) periimplant bone thickness, (2) cortical bone thickness, (3) magnitude and direction of occlusal loading, and (4) % bone-to-implant contact. Results: Implants with equivalent dimensions exhibited comparable stresses and strains in all experimental conditions. Implant diameter and periimplant bone thickness influenced stress levels. Only small-diameter (3.0 mm) 1P implants in low-density bone exhibited stress levels that might adversely affect marginal bone stability. Conclusions: Implant diameter and periimplant bone thickness influenced load distribution in bone, but the type of implant-abutment transition had no significant effect. Small-diameter 1P implants should be limited to dense bone to minimize stress concentrations.

Heat generation in 1-piece implants during abutment preparations with high-speed cutting instruments.

Objectives:Evaluation of heat generation in 1-piece implants according to 3 variables: preparation time, bur type, and preparation environment. Materials and Methods:Study implants were 1-piece designs with the same endosseous dimensions and surface microtexture, but with abutment sections that were either conical in shape, which required clinical preparations to shape and establish a restorative finish line (test), or with a pre-machined shape and restorative margin, which required minimal preparations (control) to accommodate a cemented crown. Burs were either carbide (group 1) or diamond (group 2), and the preparation environment was either ambient air or under water spray. An infrared camera was used to measure temperature changes in the exposed endosseous implant threads during grinding procedures. Three endosseous zones of the implant body were defined for heat measurements: crestal bone region (SP01), middle of the threaded region (SPO2), and apical region (SPO3). Grinding was performed in either ambient air or under water spray. The abutment was reduced to a 2.0 mm height, and one side was ground down to a 30 degree angle. Results:Highest heat elevations were concentrated in SP01, followed by SP02 and SP03. Average temperature changes in SP01 showed that preparation time and environment significantly affected heat generation but not bur type. Lowest temperatures were exhibited by control implants prepared under water spray. Bur type (carbide or diamond) did not affect temperature changes. Conclusion:Intraoral implant abutment preparations can transfer heat to the bone capable of impairing osseointegration.

Effect of implant insertion and loading protocol on long-term stability and crestal bone loss: A comparative study

STATEMENT OF PROBLEM Different insertion and loading protocols have been used to implement implant therapy; the consequences of these methods are unclear. PURPOSE The purpose of this retrospective study was to compare the long-term outcomes of different implant insertion and loading protocols on crestal bone loss. MATERIAL AND METHODS This was a nonrandomized retrospective study investigating data of patients in a private practice. Data were collected by an independent Tel Aviv University group from the patient records of a general practitioners private practice. A total of 1688 implants were inserted in 343 patients whose records met the inclusion criteria, that is, 1317 immediately placed implants (IP group), 310 early placed implants (EP group) placed 6 to 8 weeks after implant placement, and 61 delayed placement implants (DP group) placed 4 to 6 months after extraction. The groups were also divided by implant loading method, giving 1203 immediately loaded implants (IL group), 273 early loaded implants (EL group) loaded within 4 to 10 weeks after implant placement, and 212 delayed loading implants (DL group) loaded within 3 to 6 months. Mixed model analysis was used to account for the different number of implants for each patient. RESULTS The average follow-up time was 107 months, with a cumulative implant survival rate of 95.6% and an average crestal bone loss of 2.03 mm. No statistical differences (P>.05) were found among the insertion or loading protocols. However, additional statistical analysis showed the influence of implant type on marginal bone loss (P<.05). CONCLUSIONS The 3-implant insertion and loading protocols exhibited minimal crestal bone loss and a high survival rate.

An in vitro assessment of circumferential grooves on the retention of cement-retained implant-supported crowns

STATEMENT OF PROBLEM Crowns cemented on short implant abutments may have insufficient retention. PURPOSE The purpose of this study was to evaluate the effect of circumferential grooves on the retention of cemented cast copings on implant abutments. MATERIAL AND METHODS Sixty similarly-shaped implant abutments were divided into 4 groups (n=15): without grooves, with 1 groove, with 2 grooves, and with 3 grooves. Fifteen identical NiCr cast copings were prepared to fit all 60 abutments. The castings were cemented to each group of abutments with a noneugenol provisional cement (Tempbond NE) and a zinc phosphate cement (Harvard). After thermal cycling and storage for 6 days in a water bath, retention tests were conducted with a tensile testing machine (Instron) (5 mm/min) and retentive forces were recorded. Data were subjected to 1 way-ANOVA, Tukeys (HSD) test, and repeated measures ANOVA (α=.05). RESULTS For the noneugenol temporary cement, group retention values were increased according to the number of grooves (P<.001). For the zinc phosphate cement, the first groove increased the retention by approximately 60% (P<.001). The retentive values were higher for the zinc phosphate cement than the provisional cement. The influence of the grooves depended on the type of cement used (P<.001). Cement remnants were found primarily on the castings for provisional cement and for the plain abutments cemented with zinc phosphate cement. Remnants were found primarily on the abutments for the grooved abutments cemented with zinc phosphate cement. CONCLUSIONS The addition of circumferential grooves to implant abutments increased the retention of cement-retained castings. For zinc phosphate cement, 1 groove was as effective as several, whereas for the provisional cement, the retention increased gradually with additional grooves.

One Piece Immediately Loaded Implants Versus 1 Piece or 2 Pieces Delayed: 3 Years Outcome.

Purpose:To compare time-dependent outcome of immediately loaded 1-piece (1P) implants with delayed loaded 1P and 2-piece (2P) implants. Materials and Methods:A cohort of 33 patients divided into 3 groups: group A, 13 patients, 49 immediately placed and loaded 1P implants; group B, 11 patients, immediately placed and delayed loaded 1P implants; and group C, 10 patients, 39 2P implants delayed placed and loaded in a two-stage procedure. Marginal bone loss (MBL) was analyzed using x-ray radiography every 6 months, 1 year, and 3 years. Results:A statistically significant mean MBL was observed between baseline, 6 months, 1 year, and 3 years in all groups. There was no statistical significant difference in MBL between immediate and delayed loaded 1P implants. MBL around mandibular implants was lower compared with maxillary implants. Conclusions:2P implants showed less MBL compared with 1P implants in both maxilla and mandible. There was no statistical difference in MBL between immediate and delayed loaded 1P implants. Immediate loaded implants show more MBL in maxilla.

Bone Microstrain Values of 1-Piece and 2-Piece Implants Subjected to Mechanical Loading

Purpose: The purpose of this study was to measure and compare the strain levels in peri-implant bone as generated by 1-piece (1P) and 2-piece (2P) implant systems. Materials and Methods: The implants (1P and 2P) were placed into bovine bone according to the manufacturers protocol. Four linear strain gauges were placed around each implant neck and apex. Each model was loaded in static loading by a material testing machine in ascending forces ranging from 20 to 120 N. Microstrains (&mgr;[Latin Small Letter Open E]) generated in the surrounding bone were measured by a strain gauge and recorded. Results: Recorded microstrains were significantly higher for 1P implants than for 2P implants. Average recorded microstrain values were significantly lower in the neck (71.6 and 17.3 µs) compared with the apical (132 and 60 µs) regions of 1P and 2P implants, respectively (P < 0.0001). Conclusions: Within the limitations of this study, highest microstrains were generated in apical regions regardless of implant design, but the 2P implant ap-peared to provide a stress-damping effect in both the cervical and apical regions compared with the 1P implant.

Fluoride ion release and solubility of fluoride enriched interim cements

STATEMENT OF PROBLEM Interim and definitive restorations cemented with interim cements for a prolonged interval are susceptible to bacterial infiltration and caries formation. PURPOSE The purpose of this in vitro study was to evaluate the long-term fluoride release and solubility of aged ZnO-based interim cements enriched separately with 0.4% NaF and SnF2. MATERIAL AND METHODS Four different brands of cements (Tempbond, Tempbond NE, Procem, and Freegenol) were tested for fluoride release and solubility. For every test, 6 disk specimens of each cement with NaF and SnF2, and 6 with no fluoride enrichment (control) were fabricated, for a total of 72 specimens. The disks were incubated in deionized water. Fluoride ion release was recorded at 1, 7, 14, 21, 63, 91, and 182 days. Solubility was calculated as weight percent after 90 days of incubation. The data were analyzed by analysis of variance with repeated measures and the Tukey honestly significant difference post hoc test (P<.05). RESULTS Cements mixed with fluorides released fluoride ions for at least 182 days. Cements mixed with NaF released more fluoride ions than those mixed with SnF2 (P<.001). The cumulative release rates from all the tested cements mixed with either NaF or SnF2 were linear with respect to t(½) (r>.97), indicating a diffusion-controlled fluoride release. Cement and fluoride types were the main affecting factors in fluoride ion release. The addition of fluorides slightly increased the solubility of the cements. CONCLUSIONS Given their long-term sustained and diffusive controlled release, these fluorides, particularly NaF when mixed with ZnO-based interim cements, may be useful for caries prevention under provisionally cemented restorations.