The effect of a platelet-rich fibrin conduit on neurosensory recovery following inferior alveolar nerve lateralization: a preliminary clinical study

Nerve Reconstruction Using ActiGraft Blood Clot in Rabbit Acute Peripheral Injury Model: Preliminary Study

This preliminary study aimed to investigate an ActiGraft blood clot implant (RedDress Ltd., Pardes-Hanna, Israel) attempting to treat and induce the regeneration of a completely injured peripheral nerve with a massive loss defect. The tibial portion of the sciatic nerve in 11 rabbits was transected, and a 25 mm nerve gap was reconnected using a collagen tube. A comparison was performed between the treatment group (eight rabbits; reconnection using a tube filled with ActiGraft blood clot) and the control group (three rabbits; gap reconnection using an empty tube). The post-operative follow-up period lasted 18 weeks and included electrophysiological and histochemical assessments. The pathological severity score was high in the tube cross sections of the control group (1.33) compared to the ActiGraft blood clot treatment group (0.63). Morphometric analysis showed a higher percentage of the positive myelin basic protein (MBP) stained area in the ActiGraft blood clot group (19.57%) versus the control group (3.67%). These differences were not statistically significant due to the small group sizes and the large intra-group variability. The results of this preliminary study suggest that the application of an ActiGraft blood clot (into the collagen tube) can enable nerve recovery. However, a future study using a larger animal group is required to achieve objective statistical results.

Inferior alveolar nerve repositioning surgical techniques and outcomes - a systematic review

Inferior alveolar nerve (IAN) lateralization (IANL) or transposition (IANT) are both techniques allowing for dental implant placement in posterior atrophic mandibles. The aim of this study was to systematically review the implant survival rate and the complications associated with IAN reposition techniques with simultaneous implant placement in atrophic posterior mandibles. This systematic review was conducted following PRISMA guidelines (Preferred Reporting Items for Systematic review and Meta-Analysis). The review was designed to answer the following PICO question: Is IAN repositioning (I) a safe and efficient technique (O) to treat patient looking for fixed dental rehabilitation of an atrophic posterior mandible (P). Thirty-three articles were reviewed, including a total of 899 patients, and approximately 950 IAN repositioning procedures. Dental implant survival rate ranged between 86.95% and 100% with a mean dental survival rate of 90.16%. Among the 269 patients who underwent IANT, there were 93% immediate neurosensory disturbance, and 15% persistent neurosensory disturbance. Among the 350 patients who underwent IANL, there were 93% immediate neurosensory disturbance, and 6% persistent neurosensory disturbance. IANT and IANL are reliable techniques allowing safe dental implant placement in atrophic posterior mandible with high patient satisfaction. IANL seems to cause less persistent neurosensory disturbances compared to IANT. The level of evidence is poor due to the high number of bias present in the included studies. IAN neurosensory disturbance assessment should be better homogenized in order to increase comparability.

Does leucocyte- and platelet-rich fibrin enhance neurosensory recovery after genioplasty? A double-blind, split-mouth, randomised clinical trial

Neurosensory disturbances (NSD) are common after genioplasty. In this study we aimed to assess the recovery of NSDs with or without leukocyte- and platelet-rich fibrin (L-PRF) following genioplasty. In this double-blind, split-mouth, randomised clinical trial, L-PRF was applied around the mental nerve at the osteotomy site in genioplasty (treatment side). The contralateral side was considered the control side. Two-point discrimination (TPD) test, brush test, and self-reported NSDs (SR-NSD) were used to determine NSD at one, four, and 12 months after genioplasty. Twenty patients were studied. At one and four months after osteotomy, the mean scores of TPD and SR-NSDs were significantly different between the treatment and control sides (p = 0.04, p = 0.01, respectively). The mean of TPD and SR-NSDs was not statistically different on both sides 12 months after operation (p = 0.05, p = 0.71, respectively). The application of L-PRF may enhance the speed of NSD recovery four months after genioplasty.

Effects of Platelet-Rich Fibrin/Collagen Membrane on Sciatic Nerve Regeneration

ABSTRACT

Alternative treatment approaches to improve the regeneration ability of damaged peripheral nerves are currently under investigation. The aim of the current study was to evaluate the effects of leucocyte/platelet-rich fibrin (L-PRF) with or without a collagen membrane as a supporter on crushed sciatic nerve healing in a rat model. Recovery of motor function and electrophysiologic measurements were evaluated at 4 weeks postoperatively. The whole number of myelinated axons, peripheral nerve axon density, average nerve fiber diameter (μm), and G-ratio were analyzed and compered among the groups. Functional, electrophysiological, and histological evaluations showed no significant difference among the groups with the exception of the L-PRF with collagen membrane groups that showed relatively positive effects on the functional and histological nerve recovery. In addition, the collagen membrane with L-PRF can be effect in nerve regeneration.

Evaluation of the effect of the lateralized inferior alveolar nerve isolation and bone grafting on the nerve function and implant stability. (Randomized Clinical Trial)

BACKGROUND

The inferior alveolar nerve lateralization (IANL), although allows for an implant full-length mandibular height engagement, coincides with depleting the buccal bone support and sensory deficits.

PURPOSE

This study aims to assess whether interposing a bone graft coupled with securing a collagen membrane separation between the inferior alveolar nerve (IAN) and the underlying dental implants would preserve the nerve function, enhance the implant stability, and minimize the radiographic marginal bone loss.

MATERIAL AND METHODS

Eighteen patients with 30 atrophic mandibular edentulous ridges were subjected to IANL after being randomly assigned to two treatment modalities which consisted of 15 patients each. The (control group) utilized conventional IANL in direct contact with 20 implants. The (test group) implemented the IAN collagen-membrane wrapping and interposing bone graft to overlay 23 implants. The neural function, the radiographic marginal bone loss, and the implant stability quotient were assessed and compared 6 months postoperatively.

RESULTS

All the patients regained their full neurosensory function after 6 months, with statistically nonsignificant differences between both groups throughout the follow-up period. The mean marginal bone loss in the test group was (0.42 ± 0.09) mm versus (0.38 ± 0.14) mm for the control group, which was statistically similar (P = 0.401). The 6-month postoperative mean implant stability quotient values of the test group recorded (74.73 ± 2.68) versus (74.73 ± 1.79) for the control group, which was statistically nonsignificant with a value of P = 0.626.

CONCLUSION

The interposed bone graft, coupled with the collagen membrane isolation, neither subsided the neural disturbances nor enhanced the secondary implant stability and marginal bone loss.

Effect of platelet-rich and platelet-poor plasma on peri-implant innervation in dog mandibles

Background

Autologous plasma fractions, such as platelet-rich plasma (PRP) and platelet-poor plasma (PPP), contain growth factors that can enhance neural cell survival and are therefore likely to have the ability to promote nerve regeneration. The present study compared the effect of PRP and PPP application on myelinated nerve density and diameter in the peri-implant bone region. In addition, the effect of healing time on nerve regeneration was assessed.

Materials and methods

Nine beagle dogs randomly received 54 dental implants in the bilateral mandible according to a split-mouth design. Each implant was randomly assigned to one of three implant protocols: delayed implant placement with delayed loading (DIP + DL) with local application of PRP, DIP + DL with local application of PPP and DIP + DL without any plasma additive. The animals were euthanized at 1, 3, and 6 months after loading (3 dogs per time point). Block biopsies were prepared for histomorphometry in the peri-implant bone within 500 μm around the implants.

Results

Myelinated nerve fibers were identified in the trabecular bone and in the osteons near the implants surface. The nerve fibers in the PRP group (median ± IQR; 2.88 ± 1.55 μm) had a significantly (p < 0.05) greater diameter compared to the PPP (2.40 ± 0.91 μm) and control (2.11 ± 1.16 μm) group. The nerve diameter after 6 months healing (3.18 ± 1.58 μm) was significantly (p < 0.05) greater compared to 1 (2.08 ± 0.89 μm) and 3 (2.49 ± 1.22 μm) months. No significant difference was found for myelinated nerve density between groups and healing time.

Conclusions

The present study showed that the healing time significantly influenced the diameter of the myelinated nerve fibers in peri-implant bone. PRP exerted a significant effect on the diameter of the myelinated nerve fibers as compared to PPP. Large-scale animal studies and longer follow-up periods are needed to confirm these findings and to verify whether platelet plasma can facilitate nerve regeneration process.

Pedicled segmental rotation techniques for posterior mandible augmentation: a preliminary study

Rehabilitation of the atrophic posterior mandible is a challenge in dental practice. Conventional treatments include the segmental sandwich osteotomy or inlay bone grafting (IBG), onlay bone grafting (OBG), short implants, distraction osteogenesis, and inferior alveolar nerve transposition (IANT), each with its downsides. This case series is reported to introduce a modification of IBG - pedicled segmental rotation (PSR) for the reconstruction of co-existing vertical and horizontal defects in the posterior mandible. Ten healthy patients with vertical-horizontal defects (no vertical bone walls and basal bone width <5 mm) were included. Posterior mandibular defects were treated with PSR, PSR + IANT, or PSR + OBG. In PSR, a pedicle-preserved segment is up-fractured superiorly and then flipped 90° to a vertical position. The segment is then supported with inorganic bovine bone and autogenous bone particulates. Cone beam computed tomography was performed preoperatively and at the 4-month follow-up, in addition to clinical examinations. Soft tissue healing was uneventful. Radiomorphometric analysis showed a mean new bone volume of 647.79 ± 81.31 mm³ (ΔH = 7.13 mm), 836.99 ± 119.14 mm³ (ΔH = 7.8 mm), and 640.20 ± 50.13 mm³ (ΔH = 6.59) in the PSR, PSR + OBG, and PSR + IANT groups, respectively. The proposed PSR technique used in this case series showed promising results for vertical and horizontal augmentation of the atrophic posterior mandible before placement of dental implants.

Can platelet-rich fibrin accelerate neurosensory recovery following sagittal split osteotomy? A double-blind, split-mouth, randomized clinical trial

Neurosensory disturbance (NSD) is common following sagittal split osteotomy (SSO) surgery. The aim of this study was to evaluate the effect of platelet-rich fibrin (PRF) on neurosensory recovery following SSO. This double-blind, split-mouth, randomized clinical trial was performed on patients undergoing bilateral SSO. PRF was applied to one side (selected using computer randomization) after the osteotomy and before fixation. The other side served as the control. The two-point discrimination test and a brush directional stroke test were used to assess NSD at 6 and 12 months postoperative. Self-reported paresthesia was documented using a 10-point visual analogue scale (VAS). Twenty-one patients were included in the study. The results of the two-point discrimination test and the number of subjects who reported a true direction in the brush directional stroke test differed significantly between the treatment and control sides (P=0.001). The recovery of NSD (self-reported paresthesia) was better on the treatment side than on the control side (P=0.001). PRF may enhance the recovery of paresthesia following SSO.

Do short implants have similar survival rates compared to standard implants in posterior single crown?: A systematic review and meta-analysis

BACKGROUND

Short implants have been presented as an option for posterior rehabilitation in cases of poor bone height.

PURPOSE

To compare the survival rate of short implants and standard implants when used in posterior single crowns, in addition to reporting marginal bone loss, prosthetic failures, and surgical complications.

MATERIALS AND METHODS

Electronic search (PubMed, LILACS, Cochrane Library, Scopus, and Web of Science) and hand search were performed to identify all randomized controlled trials (RCTs) and controlled clinical trials (CCTs) that evaluated both short and standard implants in posterior single crowns.

RESULTS

Out of 345 articles identified by both electronic and hand search, four studies were selected (one CCT and three RCTs). The meta-analysis for the survival rate showed that there was no significant difference between the short implants and the standard ones (P = 1.00; RR:1.00; CI:0.97-1.03) performed with three RCTs for a one-year follow-up. The mean marginal bone loss ranged from 0.1 mm to 0.54 mm. Only one study reported the presence of prosthetic failures and surgical complications.

CONCLUSIONS

The survival rate of short implants was similar to the standard ones in posterior single crowns, for the one-year follow-up period. They also presented low surgical complications, prosthetic failures and marginal bone loss, being a predictable treatment for single rehabilitation in posterior tooth loss.

Circadian Rhythm Influences the Promoting Role of Pulsed Electromagnetic Fields on Sciatic Nerve Regeneration in Rats

Circadian rhythm (CR) plays a critical role in the treatment of several diseases. However, the role of CR in the treatment of peripheral nerve defects has not been studied. It is also known that the pulsed electromagnetic fields (PEMF) can provide a beneficial microenvironment to quicken the process of nerve regeneration and to enhance the quality of reconstruction. In this study, we evaluate the impact of CR on the promoting effect of PEMF on peripheral nerve regeneration in rats. We used the self-made “collagen-chitosan” nerve conduits to bridge the 15-mm nerve gaps in Sprague-Dawley rats. Our results show that PEMF stimulation at daytime (DPEMF) has most effective outcome on nerve regeneration and rats with DPEMF treatment achieve quickly functional recovery after 12 weeks. These findings indicate that CR is an important factor that determines the promoting effect of PEMF on peripheral nerve regeneration. PEMF exposure in the daytime enhances the functional recovery of rats. Our study provides a helpful guideline for the effective use of PEMF mediations experimentally and clinically.

Platelet-rich plasma for regeneration of neural feedback pathways around dental implants: a concise review and outlook on future possibilities

Along with the development of new materials, advanced medical imaging and surgical techniques, osseointegrated dental implants are considered a successful and constantly evolving treatment modality for the replacement of missing teeth in patients with complete or partial edentulism. The importance of restoring the peripheral neural feedback pathway and thus repairing the lack of periodontal mechanoreceptors after tooth extraction has been highlighted in the literature. Nevertheless, regenerating the nerve fibers and reconstructing the neural feedback pathways around osseointegrated implants remain a challenge. Recent studies have provided evidence that platelet-rich plasma (PRP) therapy is a promising treatment for musculoskeletal injuries. Because of its high biological safety, convenience and usability, PRP therapy has gradually gained popularity in the clinical field. Although much remains to be learned, the growth factors from PRP might play key roles in peripheral nerve repair mechanisms. This review presents known growth factors contributing to the biological efficacy of PRP and illustrates basic and (pre-)clinical evidence regarding the use of PRP and its relevant products in peripheral nerve regeneration. In addition, the potential of local application of PRP for structural and functional recovery of injured peripheral nerves around dental implants is discussed.