The International Journal of Oral & Maxillofacial Implants, 02/2001

Topographies of grit-blasted, etched, grit-blasted and etched, and microfabricated and etched surfaces of commercially pure titanium have been investigated. Such surface topographies vary across the scale range of interest for dental implants, extending from nanometers to millimeters. The complete characterization of topography requires the use of complementary methods. This study compared the topographic characterization methods of non-contact laser profilometry, interference microscopy, stereo-scanning electron microscopy (stereo-SEM), and atomic force microscopy. Non-contact laser profilometry was shown to be a useful method to characterize topographic features in the micron to millimeter range, whereas interference microscopy and stereo-SEM can be employed down to the submicron range. Stereo-SEM is particularly useful for quantifying topographies with complex, strongly corrugated (sharp), and high-aspect-ratio features and was shown to be complementary to non-contact laser profilometry and interference microscopy. Because of tip-related envelope problems, atomic force microscopy was not found to be suitable for the type of surfaces investigated in this study. Independent of the method used, the commonly used integral amplitude roughness parameters, such as Ra, Rq, or Rt, were often of limited value in the description of actual implant surfaces. The application of the wavelength-dependent roughness approach was shown to be an effective method for the description of surface topographies in the complete range of characteristic roughness and is also a useful means of examining the effects of surface treatment processes.

The time-intensive, multi-step process of dental implant therapy limits patient acceptance. This 3-year prospective multicenter study sought to determine the safety of an expedited therapy that consisted of loading unsplinted maxillary anterior single-tooth implants 3 weeks after 1-stage surgical placement, and determination of the peri-implant cortical bone and mucosal responses to the expedited procedure. Fifty-two patients missing 1 or 2 maxillary anterior teeth were enrolled in a study approved by the Institutional Committee on Human Subjects Research and based on strict inclusion and exclusion criteria. Astra Tech ST implants placed in a 1-stage procedure were restored 3 weeks later with ST abutments and a provisional crown (baseline); 7 to 9 weeks later, a porcelain-fused-to-metal or all-ceramic crown was cemented. Radiographic and clinical examinations were made at baseline and at 6 and 12 months. Implant survival was recorded. Cortical bone responses and peri-implant mucosal responses were evaluated. Fifty-eight implants were placed. During the 3-week period after implant placement, 4 patients were dismissed because of smoking cigarettes (a protocol deviation), and 1 patient was excluded because of deviation in loading time. Of the remaining 53 implants, 2 failed before definitive crown cementation. The resultant 96.2% survival rate was independent of implant length, tooth position, and bone quality/quantity. The mean change in marginal bone level was 0.4 mm at 12 months. The number of surfaces with plaque decreased from 3.4% at baseline to 0.5% at 12 months. The surfaces with inflammation also decreased. A mean gain in papilla length of 0.61 mm occurred, and a gain in buccal gingiva (x = 0.34 mm) was observed. A high success rate with positive tissue responses was achieved for maxillary anterior unsplinted single-tooth implants placed in a 1-stage surgery and restored at 3 weeks. This 2-component system is suited to a single-stage, rapid loading protocol for esthetic single-tooth replacement.

This article reports the 4-year interim results of a multicenter study evaluating the clinical performance of the Osseotite dental implant. At 4 study centers, 485 Osseotite implants were consecutively placed in 181 patients (219 were placed in the mandible and 266 in the maxilla). A total of 355 implants were placed in posterior regions. Short implants (10 mm or less) represented 31.5% (n = 153) of all implants placed in this study. Patients were restored with 210 restorations, distributed as 123 short-span prostheses, 58 single-tooth replacements, 28 long-span prostheses, and 1 maxillary overdenture. At this 4-year interim evaluation, the mean time from implant placement to the most recent evaluation was 52.6 ± 3.0 months, with a mean loading time of 43.3 ± 3.8 months. Of the 485 implants placed, there have been 6 failures. All implant failures occurred prior to loading and were categorized as early implant failures. Five of the 6 failures occurred in the maxilla. Only one of the 153 short implants failed to integrate. Baseline radiographs were obtained at prosthesis connection. Radiographic analysis 1 year post-restoration showed a mean bone loss of 0.09 ± 0.7 mm. From baseline to the end of the second year of function, an overall mean bone loss of 0.13 ± 0.8 mm was recorded, indicating no additional bone was lost after the first year of implant function. At 4 years, the cumulative implant success rate for all implants placed in this study was 98.7%, with a 99.4% success rate in the posterior mandible and 98.4% success rate in the posterior maxilla. Results of this 4-year interim analysis indicate that this implant achieved a high success rate in posterior regions and that all failures with this implant in this patient population occurred prior to implant loading. When the clinical success of implants 10 mm or shorter was compared to that of implants greater than 10 mm in length, the shorter implants in this study performed similarly to longer implants. Keywords: clinical trial, dental acid etching, dental implants, multicenter study, titanium

Implant failure has been associated with factors such as poor bone quality, insufficient bone volume, implant instability, unfavorable implant loading, and smoking habits. Infections and host responses may also be important factors in dental implant failure. The objectives of the present study were to identify various explanatory factors associated with titanium implant failure. Forty subjects with stage 1 non-osseointegrated titanium dental implants (NOTI) ad modum Brånemark and 40 age- and gender-matched control subjects with successfully osseointegrated titanium implants (SOTI) were studied. Clinical data and gamma G immunoglobulin (IgG) antibody titers were studied. An independent t test revealed that significantly longer implants were placed in subjects with SOTI (P .05). Statistically significant differences in bone shape and resorption (BSR) scores were found between SOTI and NOTI (P .05). Logistic regression analysis identified 3 significant explanatory outcome variables: serum antibody avidity scores for Bacteroides forsythus (P .0001), serum antibody titers to Staphylococcus aureus (P .001), and the BSR scores (P .05). Antibody avidity to B forsythus and antibody titer to S aureus were therefore the 2 most important factors associated with early implant failures and with a significant predictive ability. This indicates that immunologic factors are involved in osseointegration.

Part I of this study describes the survival of a wide-platform, wide-diameter implant (Wide-Platform Mk II). Beginning in January 1997, 85 Wide-Platform Mk II implants were placed in the jaws of 63 patients (35 males and 28 females). Male patients experienced 10 implant failures, and female patients lost 9 implants. The mean time of implant follow-up was 286 days (median, 280), with a maximum of 734 days and a minimum of 0 days. Implant loss was 19% in the mandible and 29% in the maxilla. Kaplan-Meier analysis showed a probability of implant failure after 1 year of 0.649 (confidence interval, 0.455 to 0.926) in the maxilla and of 0.751 (confidence interval, 0.616 to 0.915) in the mandible. No apparent relationship was noted between implant survival and implant length.Part II of this study evaluated the association between the survival of a new implant design and a number of potential risk factors. A retrospective chart review was conducted for all patients who received Wide-Platform Mk II implants and who agreed to allow a medical records review for research purposes. Kaplan-Meier survival curves were used to assess the probability of implant survival relative to time. The relationships between implant survival and implant location, history of tobacco use, current tobacco use, sinus grafting, bruxism, and root canal therapy were assessed by Cox proportional hazards modeling. Although the hazard ratio showed an increased risk of implant failure with some factors, particularly a history of root canal therapy in the site of implant placement (hazard ratio 3.2, P = .10), none of the factors were statistically significant. The Wide-Platform Mk II implant used in this population group was associated with a high failure rate, but the failure rate was not related to any specific risk factors reviewed.

The aim of the present study of single-tooth implants was to compare the success rate and marginal bone resorption of a narrow-diameter self-tapping implant placed in less available bone volume with the standard-diameter self-tapping implant placed in a well-dimensioned alveolar process. A new abutment technique and a different permanent abutment design were also evaluated. Fifty-five patients were included in the study; 27 patients received 28 standard-diameter (3.75-mm) implants, and 28 patients received 32 narrow-diameter (3.25-mm) implants replacing either a central or a lateral incisor in the maxilla. In an attempt to create an ideal emergence profile and to regenerate papillae, individual acrylic resin tooth-shaped temporary abutments were fabricated, based on impressions made immediately following implant placement, and connected to the implant after 6 months. A minimum of 2 months were then allowed before definitive restorative procedures were performed. Impressions were always made at the implant level. Follow-up examinations were performed at 6 months after loading and 1, 2, and 3 years after loading. Two narrow-diameter implants were lost after 6 months, but no other failures were subsequently observed in any of the groups after that. In both groups, marginal bone loss followed the same pattern and was recorded radiographically to be a mean of 0.4 mm from the first to the last examination.

Patients with reconstruction of craniofacial or intraoral defects experience a profound impact on their quality of life (QOL). This impact on QOL is influenced by the patients medical conditions and the treatment interventions. Instruments to measure general QOL have been available for many years. A major criticism of QOL instruments is that too often the questions are not specific to the particular problems of a disease or condition. A search of the literature regarding QOL measurement for patients with maxillofacial implant-supported prostheses produced a short list of instruments, none of which were sufficiently developed or suited to the patients involved in reconstructive treatment. This study was designed to develop pretreatment and posttreatment questionnaires for measuring QOL for patients with reconstruction of a craniofacial defect and patients with reconstruction of loss of specific intraoral structures utilizing an implant-supported prosthesis (eg, severe resorption of the maxilla or mandible or both). The goal was to develop brief, targeted instruments for this specific patient population. The produced instruments were sensitive and easy to administer and score, and no disruption of clinical care occurred with the administration of the questionnaires. The instruments were used with equal success both in face-to-face interviews and via mail.

The purpose of this prospective clinical study was to evaluate the efficacy of early loading of implants and to provide evidence to support simplified treatment of mandibular edentulism by using an implant designed for 1-stage surgery, combined with ball abutments to circumvent the need for a fixed prosthodontic superstructure. Historically, the recommended time between the placement and functional loading of dental implants has been 3 months in the mandible. This recommendation is the result of a systematically chosen healing time during development of implant treatment. In recent years, histologic and experimental studies have shown that specially designed implants can result in increased bone-to-implant contact at earlier healing times. Accordingly, these implants can be placed into function faster than previously recommended. In this study, 21 patients aged between 61 and 85 years with edentulous mandibles were included. All received 2 titanium plasma-sprayed, solid-screw dental implants in the interforaminal region. Ten patients had the implants loaded with an overdenture connected with ball abutments after 3 months (control group). The other 11 patients (test group) had prostheses connected to the ball abutments after a maximum of 3 weeks. Marginal bone resorption, Periotest values, and patient satisfaction were evaluated. The cumulative post-loading implant survival rate was 100% for both groups after 24 months. Marginal bone resorption after 1 year around all implants ranged from 0 to 2 mm (no significant differences between groups; P .05). Periotest values for all implants 1 year after loading were below zero (range -1 to -6). The results of this clinical trial suggest that successful early loading of 2 implants is possible provided there is uncomplicated implant placement.

Collagen degradation products of the carboxyterminal region possibly reflect bone and attachment loss. In the present study, the Serum CrossLaps One-Step enzyme-linked immunosorbent assay was used to determine a specific part of the carboxyterminal region of type I collagen, the CrossLaps. Samples of peri-implant and gingival crevicular fluid of 111 implants and 53 teeth from 47 partially or completely edentulous patients were examined in reference to levels of CrossLaps and b-glucuronidase (ßG), an established marker of periodontal disease. Clinical probing pocket depth (PPD), bleeding on probing (BOP), plaque accumulation, mobility, radiographic bone loss, and the occurrence of Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, and Prevotella intermedia were assessed. The mean values were: for PPD at implants 3.76 ± 1.41 mm, at teeth 3.44 ± 0.88 mm; for ßG at implants 0.364 ± 0.392 pU/min, at teeth 0.314 ± 0.209 pU/min; for CrossLaps at implants 0.069 ± 0.059 pmol/min, at teeth 0.082 ± 0.053 pmol/min. Bleeding on probing was significantly higher on implants than on teeth (McNemar test, P = .004). No significant difference of ßG levels was found between teeth and implants (Wilcoxon test). A negative correlation was found between ßG levels and CrossLaps levels at teeth (Pearson-rank correlation, P = .002). On implants, no significant correlation of these 2 parameters was seen, but significant correlations were found between sulcus fluid flow rate and PPD (P = .012), bG levels and bone loss (P 0.0005), and CrossLaps levels and PPD (P = .011). CrossLaps can be detected in both gingival and peri-implant crevicular fluid. While rising levels of ßG may indicate acute peri-implantitis, CrossLaps may not, but could play a role as a marker of ongoing attachment loss.

The purpose of this retrospective study was to evaluate the clinical performance of and patients satisfaction with maxillary overdentures retained by splinted and unsplinted implants. Patients who had been treated with maxillary implant-retained overdentures because of functional problems with conventional complete dentures were identified and invited to participate in the study. A total of 16 patients fulfilled the enrollment criteria and agreed to participate. Eleven patients were treated with bar-retained overdentures with 3 to 6 clips (mean follow-up 32 months), and 5 patients wore overdentures retained by 2 to 6 ball attachments (mean follow-up 54 months). All subjects were satisfied with their prostheses, and most subjects experienced improvement in their oral function after treatment with implant-retained overdentures. At the time of clinical examination, 92% (n = 77) of the 84 implants placed were functioning satisfactorily. The cumulative survival rate for the implants after 72 months was 90%. Loss of bone support correlated with peri-implant probing depth (r = 0.29; P .02). No differences in mean bone loss between the subjects with ball-retained or bar-retained overdentures were found. The presence of plaque or peri-implant bleeding was not associated with the type of attachment.

The hypothesis of the present study was that immediate loading of implant-supported restorations replacing single missing teeth could be a successful procedure. The present study compared the clinical success of immediately loaded single-tooth implants placed in fresh extraction sites to that of immediately loaded single-tooth implants placed in healed sites. From the years 1997 to 1998, 26 patients, ranging in age from 18 to 70 years, presented for the placement of 28 immediately loaded implants intended to support single-tooth ceramometal restorations. Nineteen implants were placed into fresh extraction sites, and 9 implants were placed into healed sites. Temporary prefabricated acrylic resin crowns were prepared and adjusted. At the time of traditional second-stage surgery (3 to 6 months after implantation), the implants were restored with single-tooth ceramometal prostheses. The survival rates were 82.4% and 100% for immediate and non-immediate implants, respectively. Follow-up ranged from 6 to 24 months from the day of implant placement, with a mean of 13 months for the immediate implants and 16.4 months for the non-immediate implants. Radiographic marginal bone loss after 3 to 6 months did not extend beyond the abutment-implant junction. Within the limits of the present investigation, immediate loading of single-tooth implants placed in healed sites is a possible treatment alternative. Immediate loading of single-tooth implants placed in fresh extraction sites carried a risk of failure approximating 20% in this patient population.

This clinical report presents the prosthodontic management of early peri-implant bone loss in a partially edentulous patient. Two narrow Brånemark implants (3.3 mm in diameter) were placed to retain a mandibular implant prosthesis in the area of the mandibular left second premolar and first molar. Two weeks after the prosthesis was put into function, the distal implant exhibited soft tissue reactions. Radiographically, bone corresponding to 4 threads and 7 threads was lost at the mesial and distal sites, respectively. After occlusal load reduction was made to the existing prosthesis, bone was observed to have regenerated sufficiently to restore the defect radiographically, though not to the original level. The bone remained at a similar level at 36 months after treatment.