A 7-year life table analysis from a prospective study on ITI implants with special emphasis on the use of short implants

Electrical mallet provides essential advantages in split-crest and immediate implant placement

PURPOSE

The aim of this prospective study was to compare the use of a hand mallet versus an electrical mallet in osteotome-assisted surgery for split-crest procedures.

METHODS

Partially edentulous patients, with an alveolar ridge width inferior to the optimally desirable implant diameter, were selected for this study. Forty-six split-crest procedures were performed in 46 patients. They were randomly divided in two groups: in the control group, 23 patients, the split crest was performed with osteotomes using a handheld mallet, while in the test group, 23 patients, the split crest was prepared with osteotomes using an electrical mallet. Alveolar ridge width and incision dimensions were measured with a periodontal probe, before and after the split-crest procedure. One hundred eighty-one implants were immediately placed. Follow-up examinations were performed at baseline and 6, 12, and 24 months.

RESULTS

The survival rate, at 2-year follow-up, was 98.31%. Indeed, two implants placed in the maxilla failed to integrate at second-stage surgery. The initial width of the alveolar ridge varied from 2 to 3.5 mm; the average was 2.8 ± 0.7 mm. The final ridge width varied from 5 to 8 mm; the average was 7.2 ± 1.7 mm. The split length varied from 7 to 28 mm; the average was 17.5 ± 7.7 mm. No statistically significant differences (P > 0.05) were found between test and control group in split length and alveolar width values before and after the split-crest procedure.

CONCLUSIONS

The use of a magnetic mallet provided some essential clinical advantages during crest splitting and immediate implant placement in comparison with a hand mallet.

Peri- and intra-implant bone response to microporous Ti coatings with surface modification

Bone growth on and into implants exhibiting substantial surface porosity is a promising strategy in order to improve the long-term stable fixation of bone implants. However, the reliability in clinical applications remains a point of discussion. Most attention has been dedicated to the role of macroporosity, leading to the general consensus of a minimal pore size of 50-100 μm in order to allow bone ingrowth. In this in vivo study, we assessed the feasibility of early bone ingrowth into a predominantly microporous Ti coating with an average thickness of 150 μm and the hypothesis of improving the bone response through surface modification of the porous coating. Implants were placed in the cortical bone of rabbit tibiae for periods of 2 and 4 weeks and evaluated histologically and histomorphometrically using light microscopy and scanning electron microscopy. Bone with osteocytes encased in the mineralized matrix was found throughout the porous Ti coating up to the coating/substrate interface, highlighting that osseointegration of microporosities (<10 μm) was achievable. The bone trabeculae interweaved with the pore struts, establishing a large contact area which might enable an improved load transfer and stronger implant/bone interface. Furthermore, there was a clear interconnection with the surrounding cortical bone, suggesting that mechanical interlocking of the coating in the host bone in the long term is possible. When surface modifications inside the porous structure further reduced the interconnective pore size to the submicrometer level, bone ingrowth was impaired. On the other hand, application of a sol-gel-derived bioactive glass-ceramic coating without altering the pore characteristics was found to significantly improve bone regeneration around the coating, while still supporting bone ingrowth.

Short dental implants in reduced alveolar bone height: a review of the literature

Background

The purpose of this study was to evaluate the use of short dental implants in distally reduced alveolar bone height.

Material/Methods

MedLine (PubMed and Ovid), ISI Web of Knowledge, and Cochrane databases were used for analysis. Searching was conducted using the search equation: ‘Dental Implants’ [Majr] AND (Short[TIAB] OR Shorter[TIAB]) AND (Implant[TIAB] OR Implants[TIAB]). Abstracts were screened by 2 independent reviewers. The articles included in the analysis were published in the English language and reported data on the use of implants with lengths below 10 mm in the posterior region with reduced alveolar bone height making the placement of longer implants impossible without additional surgical interventions. Articles concerning data on orthodontic implants and post-resection surgery reconstruction were excluded from analysis. Any disagreements between the 2 reviewers were resolved by a third reviewer. No time frame was used.

Results

Of the 791 articles initially found, automatic rejection of duplicates in the Endnotes X5 software resulted in 538 articles. After the selection of studies from databases, a bibliography of 32 eligible articles was searched for other publications. Through this method, 2 more studies were added.

Conclusions

The analysis of the results of different studies on the use of short dental implants showed that this treatment could be effective and comparable to the use of standard-length implants. This study revealed that rough-surfaced implants with lengths between 6–10 mm placed in the posterior mandible are the preferred solution. However, more detailed data will require additional prospective studies.

Biomechanical determinants of the stability of dental implants: influence of the bone-implant interface properties

Dental implants are now widely used for the replacement of missing teeth in fully or partially edentulous patients and for cranial reconstructions. However, risks of failure, which may have dramatic consequences, are still experienced and remain difficult to anticipate. The stability of biomaterials inserted in bone tissue depends on multiscale phenomena of biomechanical (bone-implant interlocking) and of biological (mechanotransduction) natures. The objective of this review is to provide an overview of the biomechanical behavior of the bone-dental implant interface as a function of its environment by considering in silico, ex vivo and in vivo studies including animal models as well as clinical studies. The biomechanical determinants of osseointegration phenomena are related to bone remodeling in the vicinity of the implants (adaptation of the bone structure to accommodate the presence of a biomaterial). Aspects related to the description of the interface and to its space-time multiscale nature will first be reviewed. Then, the various approaches used in the literature to measure implant stability and the bone-implant interface properties in vitro and in vivo will be described. Quantitative ultrasound methods are promising because they are cheap, non invasive and because of their lower spatial resolution around the implant compared to other biomechanical approaches.

Accuracy of vertical height measurements on direct digital panoramic radiographs using posterior mandibular implants and metal balls as reference objects

OBJECTIVES

Conventional panoramic radiography, a widely used radiographic examination tool in implant treatment planning, allows evaluation of the available bone height before inserting posterior mandibular implants. Image distortion and vertical magnification due to projection geometry is well described for rotational panoramic radiographs. To assess the accuracy of vertical height measurements on direct digital panoramic radiographs, implants and metal balls positioned in the posterior mandible were used as radio-opaque reference objects. The reproducibility of the measuring method was assessed by the inter- and intraobserver agreements.

METHODS

Direct digital panoramic radiographs, performed using a Kodak 8000C (Eastman Kodak Company, Rochester, NY), of 17 partially edentulous patients (10 females, 7 males, mean age 65 years) were selected from an X-ray database gathered during routine clinical evaluation of implant sites. Proprietary software and a mouse-driven calliper were used to measure the radiological length of 25 implants and 18 metal reference balls, positioned in mandibular posterior segments. The distortion ratio (DR) was calculated by dividing the radiological implant length by the implant's real length and the radiological ball height by the ball's real height.

RESULTS

Mean vertical DR was 0.99 for implants and 0.97 for balls, and was unrelated to mandibular sites, side, age, gender or observer. Inter- and intraobserver agreements were acceptable for both reference objects.

CONCLUSIONS

Vertical measurements had acceptable accuracy and reproducibility when a software-based calibrated measurement tool was used, confirming that digital panoramic radiography can be reliably utilized to determine the pre-operative implant length in premolar and molar mandibular segments.

Biomechanics and load resistance of short dental implants: a review of the literature

This paper was aimed to review the studies published about short dental implants. In the focus were the works that investigated the effect of biting forces of the rate of marginal bone resorption around short implants and their survival rates. Bone deformation defined by strain was obviously higher around short implants than the conventional ones. The clinical outcomes of 6 mm short implants after 2 years showed a survival rate of 94% to 95% and lower survival rate (<80%) for 7 mm short implants after 3 to 6 years for single crown restorations. The short implants used for supporting fixed partial prostheses had a survival rate of 98.9%. Short implants can be considered as a good alternative implant therapy to support single crown or partial fixed restorations.

Clinical evaluation of short and wide-diameter implants immediately placed into extraction sockets of posterior areas: a 2-year retrospective study

The objective of the study was to determine the short-term success rate of short and wide single-tooth implants, immediately placed into extraction sockets of the posterior area. A retrospective cohort study design was used. A total of 145 subjects received 162 short and wide-diameter single-tooth implants between 2006 and 2009. A minimal 7-mm residual height and 9-mm ridge width was available in all the implant sites, and the attached gingivae were at least 2 mm wide. All implants were placed and restored with the single crown by one experienced operator. The data were analyzed with descriptive statistics. All implants were placed in molar areas. There were 20 Ankylos implants with a diameter 5.5 or 7 mm and a length of 8 mm and 142 hydroxyapatite-coated implants with a diameter 5 or 6 mm and a length of 5.7 to 8 mm. One of the 162 implants failed before prosthetic restoration, resulting in a survival rate of 99.4% after loading. Patients were followed for up to 56 months (mean = 24 months) after loading of implants. The radiographic and clinical data revealed well-maintained hard and soft tissues with acceptable short-term results. For residual ridges with minimal height but adequate width, the immediate placement of short and wide-diameter implants in fresh extraction sockets may offer a simple and predictable treatment alternative if implants are positioned appropriately after a thorough preoperative analysis.

A 5- to 6-year radiological evaluation of titanium plasma sprayed/sandblasted and acid-etched implants: results from private practice

OBJECTIVES

This study aimed to determine bone level changes after 5-6 years of follow-up for a large group of one-stage dental implants consecutively placed in private practice. Potential confounding factors influencing crestal bone loss (CBL) were also assessed.

MATERIALS AND METHODS

A total of 378 transmucosal Straumann implants in 174 patients were examined radiographically. Half of the study population (189 implants) had a titanium plasma sprayed (TPS) surface, and the other half (189 implants) were sandblasted and acid-etched (SLA). Mean CBL was measured from 5 to 6 years post-operative radiographs on the basis of known implant landmarks. Correlations of increased CBL with various independent variables were also investigated. Statistical analyses were performed using generalized estimating equations.

RESULTS

Radiographic measurements showed a CBL ≤ 1.5 mm for 65% of studied implants. A CBL > 1.5 mm was found for 28% of implants, while 7% of implants had a CBL ≥ 3 mm. Three factors significantly influenced CBL (P < 0.05): implant surface texture (TPS > SLA), smoking status (smokers > non-smokers), and implant location (anterior > posterior).

CONCLUSIONS

CBL was ≤1.5 mm after 5-6 years for the majority of followed implants. For implants with a CBL > 1.5 mm, statistically significant correlations were found for TPS surface type, anterior jaw locations, and smoking. Implant length did not influence CBL.

Osteotome sinus floor elevation with and without grafting material in the severely atrophic maxilla. A 1-year prospective randomized controlled study

OBJECTIVES

(1) To measure and compare endo-sinus bone levels around implants randomly placed with an osteotome sinus floor elevation (OSFE) procedure in grafted (control) and non-grafted (test) sinuses, (2) to evaluate the OSFE efficacy with short, tapered, and chemically modified hydrophilic surfaced implants in extremely atrophic maxillae, (3) to show that fused corticals may constitute a complication risk.

MATERIAL AND METHODS

The TE(®) SLActive 8 mm-long implants (Straumann AG) were placed using an OSFE procedure in 4 mm or less of bone height. Healing time before prosthetic rehabilitation was 10 weeks. One year after implant placement, bone levels were measured on standardized periapical radiographs.

RESULTS

Thirty-seven (17 tests, 20 controls) implants were placed in 12 patients with a mean maxillary residual bone height (RBH) of 2.4 ± 0.9 mm. Before loading, two control implants failed (RBH 1.4 and 1.2 mm); two others rotated at loading (one test, RBH 0.9 mm; one control, RBH 1.5 mm) but were uneventfully loaded after three additional months of healing. These adverse events and complications occurred when implants were placed in merged corticals. Endo-sinus bone gain was 3.9 ± 1.0 and 5.0 ± 1.3 mm for the test and control groups (P = 0.003). The 1-year success rate was 100% and 90%, respectively (P = 0.49).

CONCLUSION

Although more bone is gained when grafting material is used, this may not be required to promote endo-sinus bone gain. The OSFE procedure with or without grafting material could be efficient when the RBH is ≤ 4 mm. However, when both corticals merged, the risk of complication could increase.

Are short dental implants (<10 mm) effective? a meta-analysis on prospective clinical trials

BACKGROUND

This study aims to compare the survival rate of short (<10 mm) and standard (≥10 mm) rough-surface dental implants under functional loading.

METHODS

An electronic literature search using PubMed and Medline databases was conducted. Prospective clinical human trials, published in English from January 1997 to July 2011, that examined dental implants of <10 mm with a 12-month follow-up were included in this meta-analysis. The following data were retrieved from the included articles: the number of implants, implant dimensions, implant locations, types of prostheses, follow-up periods, and implant survival rates. Kaplan-Meier survival estimates and the hazard rates were analyzed and compared between short and standard implants.

RESULTS

Thirteen studies were selected, examining 1,955 dental implants, of which 914 were short implants. Short dental implants had an estimated survival rate of 88.1% at 168 months, when standard dental implants had a similar estimated survival rate of 86.7% (P = 0.254). The peak failure rate of short dental implants was found to occur between 4 and 6 years of function. This occurred at an earlier time point compared with standard dental implants, where the peak failure rate occurred between 6 and 8 years of function.

CONCLUSIONS

This study shows that in the long term, implants of <10 mm are as predictable as longer implants. However, they fail at an earlier stage compared with standard implants.

Texture analysis of computed tomographic images in osteoporotic patients with sinus lift bone graft reconstruction

OBJECTIVE

Bone implants are now widely used to replace missing teeth. Bone grafting (sinus lift) is a very useful way to increase the bone volume of the maxilla in patients with bone atrophy. There is a 6- to 9-month delay for the receiver grafted site to heal before the implants can be placed. Computed tomography is a useful method to measure the amount of remaining bone before implantation and to evaluate the quality of the receiver bone at the end of the healing period. Texture analysis is a non-invasive method useful to characterize bone microarchitecture on X-ray images.

PATIENTS AND METHODS

Ten patients in which a sinus lift surgery was necessary before implantation were analyzed in the present study. All had a bone reconstruction with a combination of a biomaterial (beta tricalcium phosphate) and autograft bone harvested at the chin. Computed tomographic images were obtained before grafting (t0), at mid-interval (t1, 4.2 ± 0.7 months) and before implant placement (t2, 9.2 ± 0.6 months). Texture analysis was done with the run-length method.

RESULTS

A significant increase of texture parameters at t1 reflected a gain of homogeneity due to the graft and the beginning of bone remodeling. At t2, some parameters remained high and corresponded to the persistence of bone trabeculae while the resorption of biomaterials was identified by other parameters which tended to return to pregraft values.

CONCLUSION

Texture analysis identified changes during the healing of the receiver site.

CLINICAL RELEVANCE

The method is known to correlate with microarchitectural changes in bone and could be a useful approach to characterized osseointegrated grafts.

Short implants in partially edentuolous maxillae and mandibles: a 10 to 20 years retrospective evaluation

Purpose. Evaluation of the short implant (8 mm in height) long-term prognosis and of the implant site influence on the prognosis. Methods. A longitudinal study was carried out on 121 patients (57 males and 64 females) consecutively treated with 257 implants. 108 implants were short. Results. Four (3.6%) short implants supporting fixed partial prostheses failed. Similarly, three standard implants supporting fixed partial prostheses and one supporting single-crown prosthesis failed. Mean marginal bone loss (MBL) and probing depth (PD) of short and standard implants were statistically comparable (P > .05). The 20-year cumulative survival rates of short and standard implants were 92.3 and 95.9%, respectively. The cumulative success rates were 78.3 and 81.4%. The survival rates of short implants in posterior and anterior regions were comparable: 95 and 96.4%, respectively. The difference between survival rates was not significant (P > .05). Conclusions. The high reliability of short implants in supporting fixed prostheses was confirmed. Short and standard implants long-term prognoses were not significantly different. The prognosis of short implants in posterior regions was comparable to that of in anterior regions. Nevertheless, a larger sample is required to confirm this trend.

Short implants: A systematic review

BACKGROUND

Short implants are manufactured for use in atrophic regions of the jaws. Although many studies report on short implants as ≤10 mm length with considerable success, the literature regarding survival rate of ≤7 mm is sparse.

PURPOSE

The purpose of this study was to systematically evaluate the publications concerning short dental implants defined as an implant with a length of ≤7 mm placed in the maxilla or in the mandible.

MATERIALS AND METHODS

A Medline and manual search was conducted to identify studies concerning short dental implants of length ≤7 mm published between 1991 and 2011. The articles included in this study report data on implant length ≤7 mm, such as demographic variables, implant type, location in jaws, observation time, prostheses and complications.

RESULTS

The 28 included studies represent one randomized controlled trial, 12 prospective studies and 10 retrospective studies. The survival rate of short implant was found to be increased from 80% to 90% gradually, with recent articles showing 100%.

CONCLUSION

When severe atrophy of jaws was encountered, short and wide implants can be placed successfully.

Influence of healing time on the ultrasonic response of the bone-implant interface

The aim of the present study is to investigate the effect of bone healing on the ultrasonic response of coin-shaped titanium implants inserted in rabbit tibiae. The ultrasound response of the interface was measured in vitro at 15 MHz after 7 and 13 weeks of healing time. The average value of the ratio r between the amplitudes of the echo of the bone-implant interface and of the water-implant interface was determined. The bone-implant contact (BIC) was measured by histomorphometry and the degree of mineralisation of bone was estimated qualitatively by histologic staining. The significant decrease of the ultrasonic quantitative indicator r (p = 2.10⁻⁴) vs. healing time (from r = 0.53 to r = 0.49) is explained by (1) the increase of the BIC (from 27% to 69%) and (2) the increase of mineralization of newly formed bone tissue, both phenomena inducing a decrease of the gap of acoustical impedance.

Biomechanical analysis of the effects of implant diameter and bone quality in short implants placed in the atrophic posterior maxilla

Short dental implant (SDI) placement has been proposed as an alternative to reduce the surgical risks related to the advanced grafting procedures. The aim of this study was to simulate the biomechanical behaviors and influences of SDI diameters under various conditions of bone quality by using a validated finite element (FE) model for simulation. The CT image and CAD system were combined to construct the FE models with 6 mm length SDIs for 6, 7 and 8 mm diameters under three types of bone qualities, from normal to osteoporotic. The simulated results showed that implant diameter did not influence the von Mises strains of bone under the vertical load. The bone strains increased about 58.58% in the bone of least density under lateral load. Lateral loads induced high bone strain and implant stress than vertical loads. The bone strains of 7 mm- and 8 mm-diameter short implants were not different, and both were about 52% and 66% compared to those of 6 mm-wide short implant under lateral loads. The von Mises stress of the SDIs and their compartments were all less than the yield stress of the material under vertical and lateral loads. SDIs with diameter of 7 mm or above may have better mechanical transmission in the same length at feasible condition. Attaining a proper occlusal scheme design or selective occlusal adjustments to reduce the lateral occlusal force upon the SDIs is recommended.

Impact of dental implant length on early failure rates: a meta-analysis of observational studies

AIM

To test the null hypothesis of no difference in failure rates of short (minimum length: 7 mm) and longer dental implants (≥ 10 mm), a meta-analysis was performed on prospective observational trials.

MATERIALS AND METHODS

A systematic electronic and hand search was performed to identify eligible studies. Having additional data supplied by the authors, 54 publications were included (19,083 implants).

RESULTS

In case of mandibular implants, the null hypothesis of no impact of reduced implant length on failure within the first year of prosthetic loading could not be rejected. A significant impact of implant length could be substantiated for short machined implants in the anterior [odds ratio (OR) 5.4] and posterior maxilla (OR 3.4), while short rough-surfaced implants demonstrated increased failure rates in the anterior maxillary sites. No influence of implant diameter and denture type on the failure rate of short implants could be revealed.

CONCLUSION

In areas of reduced alveolar bone height the use of short dental implants may reduce the need for invasive bone augmentation procedures.

Numerical simulation of ultrasonic wave propagation for the evaluation of dental implant biomechanical stability

Osseointegration of dental implants remains poorly understood. The objective of this numerical study is to understand the propagation phenomena of ultrasonic waves in prototypes cylindrically shaped implants and to investigate the sensitivity of their ultrasonic response to the surrounding bone biomechanical properties. The 10 MHz ultrasonic response of the implant was calculated using a finite difference numerical simulation tool and was compared to rf signals taken from a recent experimental study by Mathieu et al. [Ultrasound Med. Biol. 37, 262-270 (2011a)]. Reflection and mode conversion phenomena were analyzed to understand the origin of the different echoes and the importance of lateral wave propagation was evidenced. The sensitivity of the ultrasonic response of the implant to changes of (i) amount of bone in contact with the implant, (ii) cortical bone thickness, and (iii) surrounding bone material properties, was compared to the reproducibility of the measurements. The results show that, either a change of 1 mm of bone in contact with the implant, or 1.1 mm of cortical thickness or 12% of trabecular bone mass density should be detectable. This study paves the way for the investigation of the use of quantitative ultrasound techniques for the evaluation of bone-implant interface properties and implant stability.

Clinical evaluation of split-crest technique with ultrasonic bone surgery for narrow ridge expansion: status of soft and hard tissues and implant success

PURPOSE

The aim of this study was to evaluate the split-crest technique with ultrasonic bone surgery for implant placement in patients with narrow ridges, focusing on the status of soft and hard tissues and on implant success rate, at least 6 months after implant loading.

MATERIALS AND METHODS

During September 2007 and November 2008, 15 patients received 37 implants (BTI implants) with split-crest surgical procedure using ultrasonic bone surgery. Plasma rich in growth factors (PRGF®) was applied during split crest procedure to promote tissue regeneration. Implant surfaces were humidified with PRGF to accelerate osseointegration. Patients were recalled for a final clinical evaluation at least 6 months after implant loading. Clinical assessment included the status of soft and hard tissues around implants, and implants' success rate.

RESULTS

Thirty-seven implants in 15 patients were evaluated between July 2009 and January 2010. The status of soft tissues was very good, showing adequate plaque index, bleeding index, and probing depth values. Success rate of implants at the end of follow-up (between 11 and 28 months after insertion) was 100%. Bone ridge was measured and compared at final examination showing a mean ridge expansion of 3.35 mm (SD: 0.34).

CONCLUSIONS

Split-crest with ultrasonic bone surgery can be considered an effective and safe procedure for narrow ridge expansion.

A wide-body implant as an alternative for sinus lift or bone grafting

PURPOSE

The aim was to evaluate the outcome of a short wide-body implant in the atrophic posterior jaw without a grafting procedure.

MATERIALS AND METHODS

Patients treated with a tapered wide-body implant measuring 8 to 9 mm in width and 7 to 9 mm in length (Max implant; Southern Implants, Irene, South Africa) were recalled to scrutinize implant survival. Preoperative cone beam computed tomography images were analyzed to measure bone height in reference to the mandibular canal and sinus floor.

RESULTS

There were 57 implants inserted in 18 men and 24 women after a 2-stage procedure and delayed loading. The mean follow-up was 15 months (SD, 10; range, 1-32 months), with 63.2% of the implants having at least 1 year of follow-up and 26.3% having at least 2 years' follow-up. Forty-six implants were inserted in the posterior maxilla and eleven in the mandible. Fifteen were placed in an extraction socket and forty-two in healed bone. Thirteen implants were supporting a single crown. Two implants failed, resulting in a survival rate of 96.5%, with rates of 90.9% and 97.8% for mandible and maxilla, respectively. This was not affected by gender, jaw, immediate or delayed placement, implant diameter and length, or the use of a bone substitute. The mean preoperative bone height was 7.21 mm in maxilla and 8.76 mm in mandible. In 41 cases implant length surpassed available bone height.

CONCLUSIONS

Despite the compromised bone condition and height, the survival rate of 96.5% is comparable to normal implants and, therefore, placing a wide-body implant may be an alternative to avoid grafting procedures. This is probably related to the enlarged implant surface area and the good primary stability.

Osteotome-mediated sinus floor elevation using only platelet-rich fibrin: an early report on 110 patients

PURPOSE

This article describes a technique and reports on the early healing for localized sinus augmentation using a crestal approach in combination with an autologous leukocyte- and platelet-rich fibrin (PRF) concentrate.

MATERIALS

From November 2008 to January 2010, 138 implants were placed in 110 patients using osteotome-mediated sinus floor elevation (OMSFE) with PRF.

RESULTS

The mean residual subantral bone height of the alveolar ridge was 6.6 mm (range, 4-8 mm). The mean increase in the height of implant sites by OMSFE/PRF was 3.4 mm (range, 2.5-5 mm). A variety of 8- to 11.5-mm long (mean length, 10.1 mm) and 3.5- to 6-mm wide (mean width, 4.4 mm) screw-type implants were used. Of the 138 implants that had been placed, 97 have been restored and in function for an average loading time of 5.2 months (range, 1-11 months). The mean healing time for the loaded implants was 4 months until abutment insertion (range, 3-5 months). Three implants failed before loading for an early survival rate of both loaded and unloaded implants of 97.8%.

CONCLUSIONS

Early review of the OMSFE/PRF technique presented for localized sinus floor elevation and implant placement demonstrates a high degree of safety and success at sites with 5- to 8-mm residual subantral bone height.

Ultrasonic evaluation of dental implant biomechanical stability: an in vitro study

Dental implants are widely used for oral rehabilitation. However, there remain risks of failure that are difficult to anticipate. The objective of this ex vivo study is to investigate the potentiality of quantitative ultrasound (QUS) to assess the amount of bone in contact with titanium prototype cylindrical implants. Four groups of 10 rabbit femurs each are considered, corresponding to different amounts of bone in contact with the implant. The 10 MHz ultrasonic response of the implant is processed to derive a quantitative indicator I, based on the temporal variation of the signal amplitude. Analysis of variance (ANOVA) (p < 10(-5)) tests revealed a statistical distribution of I significantly correlated with the amount of bone in contact with the cylinders. An analytical model considering the propagation of lateral waves allows the understanding of the physical origin of the echoes. QUS technique may be used to investigate the amount of bone in contact with a cylinder implant.

Dental implant failure associated with a residual maxillary cyst

A 53-year-old male underwent oral implantation including bone grafting to substitute tooth 12. Three months post-operatively, the implant migrated apically into a cyst cavity. The implant, cyst and bone graft were removed. This report regards the migration of an implant into a residual cyst; some anatomical, clinical and pathological considerations arise from this case.

Use of tilted implants in treatment of the atrophic posterior mandible: a preliminary report of a novel approach

PURPOSE

Restoration of the atrophic partially edentulous posterior mandible with implant retained prostheses has proved to be problematic, with no ideal treatment modality. The purpose of this report is to offer a novel method of treatment using tilted endosseous implants.

MATERIALS AND METHODS

A total of 64 patients with edentulous spans of the mandible and less than 9.5 mm of alveolar bone overlying the inferior alveolar nerve had implants placed. The implants were placed in a bicortical manner with the porous hydroxyapatite placed subperiosteally if more than 1 mm of the apex of the implant was placed beyond the lingual cortex of the mandible. These implants were allowed to osseointegrate for 3 to 5 months and restored using custom-angled abutments.

RESULTS

A total of 196 implants were placed in 64 patients from March 2003 through July 2008. Two implants were lost owing to a lack of osseointegration. No implants were lost because of prosthodontic failure. No damage to the neurovascular structures or permanent paresthesia was noted.

CONCLUSIONS

Our initial results have shown that the use of tilted implants combined with custom abutments is a viable treatment modality for patients with atrophic edentulous mandibular spans that lack the required alveolar height for traditional dental implants.

Sinus lift augmentation and beta-TCP: a microCT and histologic analysis on human bone biopsies

Sinus lift elevation is an interesting method to restore bone mass at the maxilla in edentulated patients. We have investigated the histological effects of beta tricalcium phosphate (beta-TCP) combined with autograft bone for sinus lift elevation. A series of 14 patients who were candidate for dental implantation were grafted with beta-TCP granules and morcellized autograft bone harvested at the chin. beta-TCP was characterized by scanning electron microscopy and optical profilometry. Before implant placement, a small bone biopsy (2mm in diameter) was done. The amount of residual material and newly formed bone were determined by microcomputed tomography. Histological analysis was done on undecalcified sections stained by Goldner's trichrome and osteoclast identification (TRAcP). beta-TCP served as a template for bone apposition by osteoblasts onto the granules' surface. The material was simultaneously resorbed by TRAcP positive osteoclasts and macrophages. Fragments of the material remained buried in bone trabeculae as long as 12 months post-graft but the formed bone onto the granules surface had a lamellar texture. beta-TCP combined with autograft bone appears a suitable biomaterial for sinus lift augmentation before the placement of bone implants. The material favors the apposition of lamellar bone by osteoblasts and is simultaneous resorbed by two types of cells.

To what extent does the crown-implant ratio affect the survival and complications of implant-supported reconstructions? A systematic review

OBJECTIVE

To evaluate the occurrence of biological and technical complications with respect to the crown-implant (C/I) ratio of implant-supported reconstructions.

MATERIAL AND METHODS

Electronic (MEDLINE) and hand searches were conducted for longitudinal prospective studies with a follow-up period of at least 4 years. One reviewer performed screening and data abstraction. The following complications were evaluated: implant survival, peri-implant crestal bone loss, implant fracture, and technical complications related to implant components and suprastructure.

RESULTS

The search provided 41 articles and abstracts, seven of which were selected for full-text analysis. Only two articles were finally included. A qualitative data analysis revealed that the survival rate of implant-supported reconstructions with a C/I ratio of more than 2 was 94.1%. In addition, peri-implant crestal bone loss seemed not to be influenced by the C/I ratio of the implant rehabilitation, except in one study, which noted greater crestal bone loss with lower (<1) compared with higher (>2) C/I ratios. Technical complications related to implant components and suprastructure according to different C/I ratios were not found in any of the studies.

CONCLUSIONS

Despite the diversity among studies with respect to data collection and study design, the current literature shows that the C/I ratios of implant-supported reconstructions do not influence peri-implant crestal bone loss.

Early loading after 21 days of healing of nonsubmerged titanium implants with a chemically modified sandblasted and acid-etched surface: two-year results of a prospective two-center study

PURPOSE

The aim of this two-center study was to evaluate screw-type titanium implants with a chemically modified, sandblasted and acid-etched surface when placed in the posterior maxilla or mandible, and loaded 21 days after placement.

MATERIAL AND METHODS

All 56 patients met strict inclusion criteria and provided informed consent. Each patient displayed either a single-tooth gap, an extended edentulous space, or a distal extension situation in the posterior mandible or maxilla. Eighty-nine dental implants (SLActive, Institut Straumann AG, Basel, Switzerland) were inserted according to an established nonsubmerged protocol and underwent undisturbed healing for a period of 21 days. Where appropriate, the implants were loaded after 21 days of healing with provisional restorations in full occlusion. Definitive metal ceramic restorations were fabricated and positioned on each implant after 6 months of healing. Clinical measurements regarding soft tissue parameters and radiographs were obtained at different time points up to 24 months after implant placement.

RESULTS

Of the 89 inserted implants, two (2.2%) implants failed to integrate and were removed during healing, and two (2.2%) additional implants required a prolonged healing time. A total of 85 (95.6%) implants were therefore loaded without incident after 21 days of healing. No additional implant was lost throughout the study period, whereas one implant was lost to follow-up and therefore left unaccounted for further analysis. The remaining 86 implants all exhibited favorable radiographic and clinical findings. Based on strict success criteria, these implants were considered successfully integrated 2 years after insertion, resulting in a 2-year success rate of 97.7%.

CONCLUSION

The results of this prospective two-center study demonstrate that titanium implants with a modified SLA surface can predictably achieve successful tissue integration when loaded in full occlusion 21 days after placement. Integration could be maintained without incident for at least 2 years of follow-up.

Implant failure predictors in the posterior maxilla: a retrospective study of 273 consecutive implants

BACKGROUND

The goal of this study was to retrospectively analyze a cohort of 136 patients who underwent dental implant placement in the posterior maxilla at the University of Connecticut Health Center to assess and identify predictors for implant failure in the posterior maxilla.

METHODS

Data were retrieved from patient charts to identify subjects older than 21 years of age who received dental implant(s) in the posterior maxilla. Patients without a postoperative baseline radiograph were excluded. A recall radiograph was taken 3 to 6 months after implant placement. If there was no recall radiograph, the subject was contacted for a recall visit that included a clinical evaluation and radiographs to determine the implant status. Based on a univariate screening, variables considered potential implant failure predictors included gender, diabetes, smoking, implant length, implant diameter, membrane use, sinus-elevation technique, and surgical complications. These parameters were further assessed, and a multivariable logistic regression was performed with implant failure as a dependant variable. All tests of significance were evaluated at the 0.05 error level.

RESULTS

Two hundred seventy-three implants were placed in the posterior maxilla. Fourteen implants failed (early and late failures combined), resulting in a 94.9% overall survival rate. The survival rates for the sinus-elevation group and native bone group were 92.2% and 96.7%, respectively (P = 0.090). Based on the multivariable analysis, sinus floor-elevation procedures were not associated with increased risk for implant failure (P = 0.702). In contrast, smoking and surgical complications had a statistically significant effect on implant failure; the odds ratios for implant failure were 6.4 (P = 0.025) and 8.2 (P = 0.004), respectively.

CONCLUSION

Sinus-elevation procedures with simultaneous or staged implant placement do not increase the risk for implant failure, whereas smoking and surgical complications markedly increase the risk for implant failure.

Five-year clinical evaluation of short dental implants placed in posterior areas: a retrospective study

BACKGROUND

The aims of this study were to evaluate the long-term survival rates of short dental implants in posterior areas and to analyze the influence of different factors on implant survival.

METHODS

A retrospective cohort study design was used. A total of 293 subjects received 532 short implants between 2001 and 2004. All implants were placed by two experienced surgeons, and rehabilitations were done by three prosthodontists. Each implant failure was analyzed carefully. The potential influence of demographic factors, clinical factors, surgery-dependent factors, and prosthetic variables on implant survival was studied. Implant survival was analyzed using a life-table analysis (Wilcoxon [Gehan] test).

RESULTS

The overall survival rates of short implants were 99.2% and 98.7% for the implant- and subject-based analyses, respectively. The mean follow-up period was 31 +/- 12.3 months. Two of 532 implants were lost during the observation period. None of the variables studied were statistically associated with implant failure.

CONCLUSION

Treatment with short implants can be considered safe and predictable if used under strict clinical protocols.