Different loading times for dental implants - no clinically important differences?

The Effect of Polybutylcyanoacrylate Nanoparticles as a Protos Delivery Vehicle on Dental Bone Formation

BACKGROUND

Dental implants are commonly used for missing teeth, for which success depends heavily on the quality of the alveolar bone. The creation of an ideal implant site is a key component in shortening the treatment time, which remains clinically challenging. Strontium ranelate (Protos) is an anti-osteoporotic agent which has previously been used to promote bone formation, however the systemic use of Protos has been linked to serious cardiovascular and venous thromboembolic events, thus local delivery strategies may be better suited for this purpose. In this study, a biodegradable, and biocompatible nanocarrier "polybutylcyanoacrylate" (PBCA) loaded with strontium was constructed and its ability to promote bone formation was assessed.

METHODOLOGY

PBCA nanoparticles loaded with strontium (PBCA-Sr NPs) were synthesized using the emulsion polymerization method, and their physical properties (zeta potential, size and shape) and entrapment efficiency were characterized. Committed MSCs (osteoblasts) were derived from the differentiation of cultured rat mesenchymal stem cells (MSC), which were tested with the PBCA-Sr NPs for cytotoxicity, inflammatory response, bone formation and mineralization. Scanning electron microscopy was performed following a 7-day treatment of PBCA-Sr NPs on decellularized procaine mandibular bone blocks grafted with osteoblasts.

RESULTS

Spherical PBCA-Sr NPs of 166.7 ± 2.3 nm, zeta potential of -1.15 ± 0.28 mV with a strontium loading efficiency of 90.04 ± 3.27% were constructed. The presence of strontium was confirmed by energy-dispersive X-ray spectroscopy. Rat committed MSCs incubated in PBCA-Sr NPs for 24 hrs showed viabilities in excess of 90% for concentrations of up to 250 ug/mL, the cellular expression of osteocalcin and alkaline phosphatase were 1.4 and 1.3 times higher than the untreated control, and significantly higher than those treated with strontium alone. Bone formation was evident following osteoblast engraftment on the decellularized procaine mandibular bone block with PBCA-Sr NPs, which appeared superior to those treated with strontium alone.

CONCLUSION

Treatment of committed MSCs with PBCA-Sr NPs showed higher expression of markers of bone formation when compared with strontium alone and which corresponded to greater degree of bone formation observed on the 3-dimensinal decellularized procaine mandibular bone block. Further quantitative analysis on the extent of new bone formation is warranted.

Immediate loading of implants in the edentulous mandible: a multicentre study

PURPOSE

The aim of this prospective study was to investigate the two-year outcomes following immediate loading of mono-cortically engaged implants.

MATERIALS AND METHODS

Thirty healthy mandible edentulous patients with an average age of 67.3 years and presenting with sufficient bony ridge at the mandible symphysis were included in the study. Four Astra Tech, Ti-Oblast^® implants were installed between the mental foramina using the mono-cortical anchorage technique. The primary stability of the implants was assessed by resonance frequency analysis (RFA). After uni-abutments were placed, a temporary bridge was constructed and fixed the same day. The definitive bridges were installed 6 weeks after implant surgery. Five of 120 placed implants were lost in four patients during the first 6 weeks and these patients were excluded from the follow-up. The changes in marginal bone level (n = 20) were evaluated in Brazilian and Swedish groups at baseline, 6 weeks, 6 months, 12 months and 24 months. The RFA (n = 30) was evaluated at baseline, 6 weeks, 6 months, 12 months and 24 months postoperatively.

RESULTS

Compared with baseline measurements, the postoperative values for marginal bone level (6 weeks, 6 months, 12 months and 24 months) were significantly reduced (p < 0.05), while no differences were observed in the RFA analysis (12 months and 24 months).

CONCLUSIONS

The immediate loading of mono-cortically engaged implants in the edentulous mandible is safe and predictable and implant stability remains excellent after 2-year follow-up.

Clinical efficacy of early loading versus conventional loading of dental implants

The aim of this study was to determine the clinical differences between early and conventional loading protocols for dental implants. A comprehensive search of the Medline, Embase, and OVID databases for studies published through January 10, 2015 was conducted. Fourteen studies were included in our analysis. We found that early loading imposed a significantly higher risk of implant failure than did conventional loading (risk ratio = 2.09, 95% confidence interval [CI] [1.18, 3.69], P = 0.01), while no significant differences between the methods were found with regards to the marginal bone loss (weighted mean differences [WMD] = 0.11, 95% CI [-0.07, 0.28], P = 0.23), periotest value (WMD = 0.02, 95% CI [-0.83, 0.87], P = 0.96), or implant stability quotient (WMD = 0.79, 95% CI [-0.03, 1.62], P = 0.06). As for the health status of the peri-implant tissue, conventionally loaded implants demonstrated better performance than did early loaded implants. Subgroup analyses demonstrated that the sample size, time of publication, loading definition, implant position, extent, and restoration type influenced the results. Although early implant loading is convenient and comfortable for patients, this method still cannot achieve the same clinical outcomes as the conventional loading method.

Clinical efficacy of immediate implant loading protocols compared to conventional loading depending on the type of the restoration: a systematic review

BACKGROUND AND OBJECTIVES

Immediate loading has become a predictable option to restore all clinical situations. The aim of this systematic review was to assess whether immediate loading protocols achieve comparable clinical outcomes when compared to conventional loading protocols depending on the type of prosthetic restoration.

METHODS

A protocol was developed aimed to answer the following focused question: "What are the effects of immediate implant loading protocols compared to conventional implant loading, in terms of implant failure, marginal bone levels, and biological and mechanical complications based on the type of restoration?" The next subanalysis were performed as follows: the extent, type, and material of the restoration and the type of occlusal contact in function. This systematic review only included randomized controlled trials (RCTs) with a follow-up of at least 6 months after implant loading.

RESULTS

Thirty-seven final papers were included. The results from the meta-analyses have shown that the immediately loading implants demonstrated a statistically significant higher risk of implant failure [RR = 1.92; 95% CI (1.04; 3.54); P = 0.036], a statistically significant lower bone loss [WMD = 0.046; 95% CI (0.043; 0.049); P = 0.000] and a smaller increase in ISQ values [WMD = -1.096; 95% CI (-1.615; -0.577); P < 0.001, although both groups attained high survival rates (98.2% in the test and 99.6% in the control). Single teeth implants were greater risk of failure, when compared to immediately loaded full arch restorations (RR = 2 vs. 0.9), so as the occlusal pattern when compared to non-occlusal (RR = 1.9 vs. 1.4).

CONCLUSIONS

Immediate loading may impose a greater risk for implant failure when compared to conventional loading, although the survival rates were high for both groups.

Review found little difference between sandblasted and acid-etched (SLA) dental implants and modified surface (SLActive) implants

DATA SOURCES

Medline, Embase, the Cochrane Oral Health Group's Trials Register and OpenGREY databases were searched together with the reference lists of identified articles.

STUDY SELECTION

Randomised controlled trials (RCTs) and prospective cohort studies of at least six month duration were included. Studies/case series in which there was only one implant surface (SLA or SLActive) and one loading protocol (immediate or early) were also considered.

DATA EXTRACTION AND SYNTHESIS

Two reviewers screened, selected and abstracted data, independently. RCTs were assessed for quality using the Cochrane risk of bias approach and observational studies using the Newcastle-Ottawa scale (NOS). The primary outcomes were changes from baseline to follow-up of clinical attachment level (CAL), probing depth (PD) and radiographic changes in the peri-implant bone level and number of implants lost. Cumulative survival rates (%) of each included study were calculated.

RESULTS

Twenty-three articles reporting 19 studies (seven RCTs; 12 prospective observational studies) were included. The seven RCTs included 407 patients with 853 implants (8% titanium plasma-sprayed, 41.5% SLA and 50.5% SLActive). Only one RCT was considered to be at low risk of bias, the others were considered to be at unclear risk. The 12 observational studies included 1394 SLA and 145 SLActive implants and were considered to be of medium methodological quality based on the NOS. A narrative summary of the studies was undertaken owing to marked heterogeneity of the loading periods, types of implants described and lack of occurrence of the outcome of interest. There were no significant differences reported in the studies in relation to implant loss or clinical parameters between the immediate/early loading and delayed loading protocols. Overall, 95% of SLA and 97% of SLActive implants still survive at the end of follow-up.

CONCLUSIONS

Despite the positive findings achieved by the included studies, few RCTs were available for analysis for SLActive implants. Study heterogeneity, scarcity of data and the lack of pooled estimates represent a limitation between studies' comparisons and should be considered when interpreting the present findings.

Laser welded versus resistance spot welded bone implants: analysis of the thermal increase and strength

INTRODUCTION

The first aim of this "ex vivo split mouth" study was to compare the thermal elevation during the welding process of titanium bars to titanium implants inserted in pig jaws by a thermal camera and two thermocouples. The second aim was to compare the strength of the joints by a traction test with a dynamometer.

MATERIALS AND METHODS

Six pigs' jaws were used and three implants were placed on each side of them for a total of 36 fixtures. Twelve bars were connected to the abutments (each bar on three implants) by using, on one side, laser welding and, on the other, resistance spot welding. Temperature variations were recorded by thermocouples and by thermal camera while the strength of the welded joint was analyzed by a traction test.

RESULTS

For increasing temperature, means were 36.83 and 37.06, standard deviations 1.234 and 1.187, and P value 0.5763 (not significant). For traction test, means were 195.5 and 159.4, standard deviations 2.00 and 2.254, and P value 0.0001 (very significant).

CONCLUSION

Laser welding was demonstrated to be able to connect titanium implant abutments without the risk of thermal increase into the bone and with good results in terms of mechanical strength.