Osseointegration of Plateau Root Form Implants: Unique Healing Pathway Leading to Haversian-Like Long-Term Morphology

Short and Extra Short Dental Implants in Osseous Microvascular Free Flaps: A Retrospective Case Series

There is limited information regarding implant and prosthetic survival after osseous microvascular free flap (OMFF). This case series aims to describe the placement of short and extra short implants in osseous microvascular free flaps to support prostheses, and present an up to 40-month retrospective follow-up. Short and extra short dental implants were placed in six fibula free flaps (FFF) and in two microvascular deep circumflex iliac artery (DCIA) flaps. In total, 27 short and extra short dental implants have been placed into two different types of free flaps. Kaplan-Meyer (K-M) survival analyses were performed to evaluate the survival and success outcomes of implants and prostheses. Out of the eight patients reconstructed with free flap, five were rehabilitated with prostheses, one patient has a temporary prosthesis, and two patients are in the process of prosthetic rehabilitation. Twenty-seven implants were followed up for up to 40 months, and K-M analyses showed 100% implant survival probability (95% confidence interval: 100%), while the implant success probability was 91.0% (95% confidence interval: 68.6-97.7%). Short and extra short dental implants placed in OMFF presented high survival and success rates in a retrospective case series after up to 40 months.

Prefabricated shouldered abutments enable successful restoration of molar crowns on implants

PURPOSE

This retrospective study evaluated the effect of selected clinical and patient factors on survival, success, and peri-implant bone level changes of locking taper implants supporting molar crowns on Bicon's prefabricated shouldered abutments.

METHODS

A total of 234 patients, who received 274 single molar crowns supported by locking taper implants were included in this retrospective study. Kaplan-Meier survival analysis was used to assess overall implant survival, prostheses survival, and success. Crowns were either monolithic (resin based) or bilayered (milled fiber-reinforced composite coping veneered with indirect composite). Early and late changes in marginal bone levels were plotted and analyzed with equivalence testing to compare the effects of different factors on crestal bone levels.

RESULTS

At 9.5 years after implant surgery, the implant survival probability was 94.2%, the probability of prosthesis survival was 91.4%, and the probability of prosthetic success was 90.4%. Neither the use of different crown materials, nor the choice of monolithic versus bilayered crown construction, significantly affected the probability of prosthetic success. Marginal bone levels, on average, trended downwards towards the top of the implant within the first 2 years after functional loading, and remained stable on average, since then. Factors affecting bone levels included the use of nonsteroidal anti-inflammatory drugs, which precluded early implant bone loss; and subcrestal implant placement, which was linked to significantly higher long-term bone levels.

CONCLUSION

The implant and abutment system studied resulted in high implant and prosthetic survival rates, regardless of prosthetic material used, with stable bone levels over time.

Antiresorptive therapy and dental implant survival: an up to 20-year retrospective cohort study in women

OBJECTIVES

To investigate the effects of antiresorptive treatment on the survival of plateau-root form dental implants.

MATERIALS AND METHODS

Patients undergoing antiresorptive therapy via oral or intravenous administration as well as patients not undergoing antiresorptive therapy and healthy control patients were included in this retrospective cohort study. In total, 1472 implants placed in 631 postmenopausal patients (M: 66.42 ± 9.10 years old), who were followed for a period of up to 20 years (8.78 ± 5.68 years). Kaplan-Meier survival analysis was performed, and univariate and multivariate Cox regression, clustered by each patient, was used to evaluate and study factors affecting the survival of their implants.

RESULTS

Implants placed in patients undergoing oral antiresorptive treatment presented significantly higher survival rates, than implants placed in the osteoporosis/osteopenia control cohort (p value < 0.001), and similar survival rates, when compared to healthy controls (p value = 0.03). Additionally, clustered univariate and multivariate Cox regression analysis also revealed higher implant survival when oral antiresorptive drugs (p value = 0.01 and 0.007, respectively) were used, and lower implant survival in the presence of untreated osteoporosis/osteopenia (p value = 0.002 and 0.005, respectively). Overall, the 20-year implant survival in osteoporotic patients undergoing antiresorptive therapy was 94%. For the failed implants, newly replaced implants in patients under antiresorptive treatment presented a 10-year survival of 89%.

CONCLUSIONS

Long-term plateau-root form implant survival in osteoporotic patients taking oral antiresorptives was similar to a healthy population and significantly higher than the untreated controls.

CLINICAL RELEVANCE

These results suggest that plateau-root form implants provide a robust solution for treating tooth loss in patients, who are undergoing antiresorptive therapy.

Osseodensification drilling vs conventional manual instrumentation technique for posterior lumbar fixation: Ex-vivo mechanical and histomorphological analysis in an ovine model

Lumbar fusion is a procedure associated with several indications, but screw failure remains a major complication, with an incidence ranging 10% to 50%. Several solutions have been proposed, ranging from more efficient screw geometry to enhance bone quality, conversely, drilling instrumentation have not been thoroughly explored. The conventional instrumentation (regular [R]) techniques render the bony spicules excavated impractical, while additive techniques (osseodensification [OD]) compact them against the osteotomy walls and predispose them as nucleating surfaces/sites for new bone. This work presents a case-controlled split model for in vivo/ex vivo comparison of R vs OD osteotomy instrumentation in posterior lumbar fixation in an ovine model to determine feasibility and potential advantages of the OD drilling technique in terms of mechanical and histomorphology outcomes. Eight pedicle screws measuring 4.5 mm × 45 mm were installed in each lumbar spine of eight adult sheep (four per side). The left side underwent R instrumentation, while the right underwent OD drilling. The animals were killed at 6- and 12-week and the vertebrae removed. Pullout strength and non-decalcified histologic analysis were performed. Significant mechanical stability differences were observed between OD and R groups at 6- (387 N vs 292 N) and 12-week (312 N vs 212 N) time points. Morphometric analysis did not detect significant differences in bone area fraction occupancy between R and OD groups, while it is to note that OD showed increased presence of bone spiculae. Mechanical pullout testing demonstrated that OD drilling provided higher degrees of implant anchoring as a function of time, whereas a significant reduction was observed for the R group.

Histological and Histomorphometrical Evaluation of a New Implant Macrogeometry. A Sheep Study

Decompression or healing chambers between the threads have been proposed to improve and accelerate the osseointegration process of dental implants. The aim of the present work was to test, in an in vivo sheep study, if healing chambers between the threads could produce a better osseointegration process. Thirty titanium implants (15 conventional design (control) and 15 implants with healing chambers (test)) were inserted in a random fashion in the tibia of 3 sheep. The animals were euthanized after 30 days of healing, and the retrieved specimens treated to obtain thin ground sections. Histological observations showed that the quantity of newly formed bone growing in an apical direction was lower in the control group (1095 µm) when compared to the Test group (1658 µm). This difference was statistically significant. Moreover, a layer of osteogenic matrix was present around the portion of implants immersed in the marrow spaces. This osteogenic tissue was thicker in the test group. In conclusion, the present study confirmed the very good results in implants with healing chambers that presented a higher percentage of new bone formation.

Does intraoperative bone density testing correlate with parameters of primary implant stability? A pilot study in minipigs

Objectives

Bone density, surgical protocol, and implant design are the major determinants of primary stability. The goal of this animal trial was to investigate potential correlations of intraoperative bone density testing with clinical and histologic parameters of primary implant stability.

Material and methods

Following extractions of all mandibular premolars and subsequent healing, four implants each were placed in a total of four minipigs. Bone density was determined by applying intraoperative compressive tests using a device named BoneProbe whereas measurements of implant insertion torque and resonance frequency analysis were used for evaluating implant stability. Bone mineral density (BMD) and bone to implant contact were quantified after harvesting mandibular block sections. Spearman rank correlation tests were performed for evaluating correlations (α = .05).

Results

Due to variation in clinical measurements, only weak correlations could be identified. A positive correlation was found between the parameters bone to implant contact and BMD (Spearman's rho .53; p = .05) whereas an inverse correlation was observed between BMD and implant stability (Spearman's rho -.61; p = .03). Both BoneProbe measurements in the cortical and trabecular area positively correlated with implant insertion torque (Spearman's rho 0.60; p = .02). A slightly stronger correlation was observed between the average of both BoneProbe measurements and implant insertion torque (Spearman's rho.66; p = .01).

Conclusions

While establishing exact relationships among parameters of implant stability and the measurement techniques applied would require greater sample size, intraoperative compressive testing of bone might, despite the weak correlations seen here, be a useful tool for predicting primary implant stability.

Biomaterial and biomechanical considerations to prevent risks in implant therapy

This paper is aimed to present a biomaterials perspective in implant therapy that fosters improved bone response and long-term biomechanical competence from surgical instrumentation to final prosthetic rehabilitation. Strategies to develop implant surface texturing will be presented and their role as an ad hoc treatment discussed in light of the interplay between surgical instrumentation and implant macrogeometric configuration. Evidence from human retrieved implants in service for several years and from in vivo studies will be used to show how the interplay between surgical instrumentation and implant macrogeometry design affect osseointegration healing pathways, and bone morphologic and long-term mechanical properties. Also, the planning of implant-supported prosthetic rehabilitations targeted at long-term performance will be appraised from a standpoint where personal preferences (eg, cementing or screwing a prosthesis) can very often fail to deliver the best patient care. Lastly, the acknowledgement that every rehabilitation will have its strength degraded over time once in function will be highlighted, since the potential occurrence of even minor failures is rarely presented to patients prior to treatment.

In Vivo Evaluation of Dual Acid-Etched and Grit-Blasted/Acid-Etched Implants With Identical Macrogeometry in High-Density Bone

PURPOSE

Based on the current evidence, the effect of implant macrogeometry has a significant influence on osseointegration. Thus, this study evaluated histomorphometrically and histologically the bone response to acid-etched in comparison to grit-blasted/acid-etched (GB) and machined control (C) surfaced implants possessing identical macrogeometry placed in high-density bone.

MATERIALS AND METHODS

Implant surface topography of the 3 different surfaced implants has previously been characterized. The macrogeometry of the implants were conical, and healing chambers were created in the cortical regions. The 3 groups were placed in the external mandibular body of adult male sheep (n = 5). After 6 weeks in vivo, all samples were retrieved for histologic observation and histomorphometry (eg, bone-to-implant contact [BIC] and bone area fraction occupancy [BAFO]).

RESULTS

No statistical difference was observed for BIC and for BAFO, although there was a tendency that the mean values for BAFO was higher for the textured surface groups.

CONCLUSIONS

It is suggested that the effect of surface topography is minimal in high-density bone and osseointegration seemed to be macrogeometry dependent.

Effect of implant macrogeometry on peri-implant healing outcomes: a randomized clinical trial

OBJECTIVES

This randomized split-mouth clinical trial investigated the influence of implant macrogeometry on bone properties and peri-implant health parameters during the healing process.

MATERIAL AND METHODS

Ninety-nine implants were placed bilaterally in posterior mandibles of 23 patients that received at least four dental implant macrogeometries: standard geometry, Integra (IN) and three geometries inducing "healing chamber": Duo (D), Compact (C), and Infra (IF). Insertion torque (IT) and implant stability quotient (ISQ) were measured. Peri-implant health were monitored by visible plaque index (VPI), peri-implant inflammation (PI), and presence of calculus (CC). Data were collected during 90 days. Data were assessed for normality using the asymmetry and kurtosis coefficients followed by the Shapiro-Wilk test. A one-way ANOVA was used to investigate differences in IT and linear bone dimensions between the macrogeometry groups. The repeated measurements ANOVA test or ANOVA-R was used for analysis of ISQ, VPI, and PI. Tukey-Kramer test or Student's t test was used for comparisons between the groups or within each macrogeometry.

RESULTS

Macrogeometry did not significantly influence IT and ISQ values. The minimum ISQ was recorded after 7 days (71.95 ± 12.04, p = 0.0001). Intermediate ISQ was found after 14 days, when the ISQ reached values that are statistically identical to primary stability. The VPI showed significantly higher scores for the D (0.88 ± 1.03) and IN (0.72 ± 0.94) implants after 7 days. The PI was only influenced by the healing time significantly decreasing from 7 (1.07 ± 0.89) to 21 days (0.18 ± 0.18).

CONCLUSION

Implant macrogeometry did not influence IT nor ISQ values. The relationship between IT and SS was more evident for the Duo implant, but only in the final stage of healing process.

CLINICAL RELEVANCE

Show to the clinician that the macrogeometry and drilling protocols did not interfere in the clinical behavior of the implants during the healing process. However, the IT, primary and secondary stability, is quite dependent of the surgeon experience.