PUBLICATIONS

The Effect of Opposing Structures, Natural Teeth vs. Implants on Crestal Bone Levels Surrounding Single-Tooth Implants

Dec 2012 | Clinical Oral Implants Research

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Objectives: To evaluate the effect of opposing structures in crestal bone levels around single-tooth implants. Materials and methods. A retrospective cohort study design was conducted. Descriptive statistics, univariate and multifactor mixed-effects regression models, adjusted for multiple implants in the same patient were utilized to evaluate the effect of opposing structures in crestal bone levels after insertion of single-tooth replacements. Results: Eighty-one subjects who received 320 Bicon implants were included in the present study. Two hundred and thirty-one implant restorations were opposing natural teeth, 75 implants were opposing implant-supported restorations, 10 implants had no opposing structure and four implants were opposed by a complete denture. The average change in crestal bone levels overtime (AvBL) on implants opposing natural teeth and implant-supported restorations was -0.20 and -0.62mm, respectively. Hydroxyapatite-coated (HA) mandibular implants opposing natural teeth demonstrated AvBL of +0.01 (indicating bone gain), whereas titanium-plasma sprayed (TPS)-coated mandibular implants opposing implants restored with composite abutment bases demonstrated AvBL of -1.95mm. When the structure opposing an HA-coated mandibular implant was a natural tooth, it was a predictor of peri-implant bone gain (P=0.007). While TPS-coated mandibular implants, which had been restored with composite abutment bases, were correlated with peri-implant bone loss when opposed by implant-supported restorations (P=0.003). Conclusions: This study suggests that the type of opposing structure plays a significant role in mandibular crestal bone levels surrounding single-tooth implants following crown insertion but this effect differs around implants with dissimilar surface coatings and can be exacerbated by local irritating factors.

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The Survival of Ultrashort Locking Taper Implants

May 2012 | The International Journal of Oral & Maxillofacial Implants

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Abstract: To evaluate the performance of 5-mm-long implants. A retrospective cohort study was conducted between January 2008 and December 2009. The sample was composed of patients who had received at least one 5-mm-wide, hydroxyapatite-coated Bicon implant. The outcome variable was implant failure. Descriptive statistics and univariate and multivariate Cox proportional hazards regression models, adjusted for multiple implants in the same patient, were utilized to identify predictors of dental implant failure. Two hundred ninety-one subjects who received 410 locking-taper implants were followed for an average of 20 months. Of these, 211 were ultrashort implants (57 were 5 x 5.0 mm and 154 were 5 x 6.0 mm) and 199 were short implants (5 x 8.0 mm). Three hundred twenty-two implants (93.4%) were restored with single crowns. There was a higher proportion of ultrashort single-tooth implants (94.6%) as compared to short single-tooth implants (92.2%). Nine implants failed, for a cumulative survival rate of 97.5%. Of the failed implants, five were ultrashort (all 5 x 6.0 mm) and four were short. No failures were documented for 5- x 5.0-mm ultrashort implants. There was no statistically significant difference (P = .68) in the Kaplan-Meier survival rates of ultrashort implants (97.6%) and short implants (95.2%). After adjusting for other covariates in a multivariate model, implant length was not associated with implant failure (P = .49). The survival of ultrashort (5- and 6-mm) implants was comparable to that of short (8-mm) implants.

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The Effect of Implant Size 5 × 8 mm on Crestal Bone Levels Around Single-Tooth Implants

Feb 2012  |  Journal of Periodontology

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Background: There is substantial evidence supporting the strain-induced biologic response of bone to mechanical load. Stress-related factors, such as implant size, have been associated with changes in crestal bone levels on dental implants. The purpose of this study is to evaluate the effect of an implant size, specifically 5 mm wide × 8 mm long (5 × 8), on peri-implant bone levels. Methods: A retrospective cohort study was conducted. The cohort was composed of patients who had ≥1 plateau root-form implant. Descriptive statistics, univariate and multivariate mixed-effects regression models, adjusted for multiple implants in the same patient were used to evaluate the correlation between 5 × 8 implants and other clinically relevant factors on crestal bone levels after insertion of single-tooth replacements. Results: The cohort was composed of 81 individuals who received 326 implants. The average change in crestal bone levels (AvBL) for 5 × 8 maxillary and mandibular implants after 5.9 years of follow-up were -0.36 and -0.04 mm, respectively. In contrast, AvBL for mandibular implants not measuring 5 × 8 was -0.51 mm. Of several different local and systemic factors evaluated, including 10 different implant sizes, 5 × 8 mandibular implants were found to be significantly less likely to lose bone when compared with mandibular implants not measuring 5 × 8 (P = 0.047). Conclusions: Implants measuring 5 × 8 demonstrated statistically significantly less peri-implant bone loss in the posterior mandible. This finding indicated that a specific implant size may be involved in mandibular bone preservation. However, prospective multicenter clinical trials are needed to validate these findings.

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Factors Associated with Crestal Bone Gain on Single-Tooth Locking-Taper Implants:
The Effect of Nonsteroidal Anti-Inflammatory Drugs

Sep 2011 | The International Journal of Oral & Maxillofacial Implants

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Abstract: To identify factors associated with crestal bone gain around single-tooth implants. A retrospective cohort study was conducted. More than 90 different local and systemic factors were documented. Descriptive statistics and univariate and multivariate mixed-effects regression models, adjusted for multiple implants in the same patient, were used to identify predictors of crestal bone gain after insertion of definitive restorations. Eighty-one subjects who received 326 Bicon implants were followed for an average of 70.7 months. Eighty-one implants in 46 patients showed varying degrees of apparent bone gain over time. Variables associated with peri-implant bone gain in the first multivariate model were: type of opposing structure, tooth (P = .02); type of restoration, crown cemented on a prefabricated titanium abutment with a spherical base (P = .006); hydroxyapatite coating (P = .0005); implant size 5 x 8 mm (P = .02); and daily intake of nonsteroidal anti-inflammatory drugs (NSAIDs) (P =.04). NSAIDs remained significantly correlated to crestal bone gain in the second multivariate analysis; an implant was significantly more likely to gain bone if the patient was taking NSAIDs daily (P = .02), but this effect was specific to hydroxyapatite-coated implants (P = .01). Daily doses of NSAIDs were correlated with a significant increase in crestal bone levels around single-tooth hydroxyapatite-coated implants following crown insertion.

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The Effect of Increased Crown-Implant Ratio on Single-Tooth Locking-Taper Implants

Jul 2010  |  The International Journal of Oral & Maxillofacial Implants

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It has been proposed that increased crown heights lead to greater crestal stresses on dental implants, crestal bone loss, and other complications. The purpose of this study was to evaluate the effect of increased crown-to-implant ratio (C/IR) on single-tooth implants. A retrospective cohort study was conducted between July 2001 and August 2003. The cohort was composed of patients who had at least one single-tooth Bicon implant restored with a cementless restoration and attended recall examinations in 2004, 2005, and 2007, during which several clinical and radiographic variables were documented. Descriptive statistics and univariate and multivariate mixed-effects regression models, adjusted for multiple implants in the same patient, were used. The cohort was composed of 81 subjects who received 326 Bicon implants. The mean duration of follow-up was 70.7 months. Mean change in the mesiodistal crestal bone levels was -0.33 mm. The mean C/IR was 1.6 (range, 0.79 to 4.95). Forty implant restorations (16%) had a C/IR ≥ 2. Implant restorations with increased C/IR were significantly more likely to have increased mesiodistal crown width, larger implant diameter, larger distance to mesial and distal adjacent structures, and deeper sulcular probings. Increased C/IR had a statistically significant effect in the loosening of maxillary anterior Integrated Abutment Crowns (Bicon) as well as a significant effect in the fracture of 2-mm-wide titanium abutment posts used to restore posterior areas. A C/IR up to 4.95 did not lead to an increased risk of crestal bone loss or to an increase in implant failures, crown failures, or crown fractures. Larger C/IR was associated with a significant increase in prosthetic complications but had no significant effect on crestal bone levels on single-tooth locking-taper implants.

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A Screwless and Cementless Technique for the Restoration of Single-tooth Implants:
A Retrospective Cohort Study

Sep 2008  |  Journal of Prosthodontics

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The Integrated Abutment Crown (IAC) is a technique for the fabrication of single-tooth implant-supported crowns where the abutment and the crown are one unit. The abutment-crown complex is connected to the implant with a locking taper. This technique does not use cement to retain the crown or screws to retain the abutment. The purpose of this study was to evaluate the clinical outcome of screwless, cementless single implant-supported crowns (IACs) placed in a general dental practice. A retrospective cohort study was conducted between July 2001 and August 2003. Patients were recalled between January and March 2004. The restorations were evaluated following the modified United States Public Health Service (USPHS) criteria. Several other variables, such as anatomic form, occlusion, soft tissue health, and reconstructive procedures, were also recorded. Descriptive statistics, univariate and multivariate marginal Cox Proportional Hazards Regression models, adjusted for multiple implants in the same patient, were used. During the chart review, 108 patients were identified. A cohort of 59 patients with a total of 151 IACs met the inclusion criteria. The Kaplan-Meier survival rate for IACs was 98.7%. Two IACs were removed, one due to implant failure; the other became loose several times and was replaced with a splinted restoration. Excellent marginal adaptation was observed with no clinically discernible interface between the veneer material and the abutment. Nine maxillary anterior IACs loosened on five patients; eight of them were reinserted and continued in function without further problems for the remainder of the study. An IAC located between a tooth and an implant was 2.65 times more likely to have postinsertion complications (p= 0.05). An IAC with incorrect anatomic form (overcontoured) was 3.26 times more likely to have postinsertion complications (p= 0.01). Maxillary anterior IACs adjacent to one tooth and one implant were 3.9 times more likely to come loose (p= 0.05). The clinical outcome of this screwless and cementless system for single implant restorations compares favorably with the experience of screw- and cement-retained single implant restorations within the observation period.

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The Integrated Abutment Crown™, a Screwless and Cementless Restoration for
Single-Tooth Implants: A Report on a New Technique

Jul 2007 |  Journal of Prosthodontics

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A technique is presented for the restoration of single-tooth, implant-supported crowns where the abutment and the crown material are chemomechanically bonded; therefore, there is no need for cement, and the implant and implant-abutment are connected with a screwless locking-taper. The clinical and laboratory procedures involved in the fabrication and insertion of the restoration are described in detail. This restoration offers the restorative dentist some advantages: excellent marginal adaptation with a cementless interface, a bacterially sealed implant-abutment connection, a crown material with a similar wear rate and hardness values of human enamel, a simple laboratory technique, and a reduced number of prosthetic components. Due to the light-cured nature of the crown material, chairside modifications can be accomplished. The major drawbacks are: studies are necessary to assess the long-term performance of the Integrated Abutment Crown (IAC)’s in both anterior and posterior areas of the mouth. Resin materials have higher roughness values, accumulate plaque at a higher rate, and are more likely to stain than tooth structure and all-ceramic restorations.

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