Patient-matched osseointegrated prostheses for thumb amputees: a cadaver and feasibility study

Thumb amputations affect 50% of hand functionality. Common solutions consist of microsurgical treatments or silicone vacuum prosthesis. Not all patients are eligible for microsurgical treatment and the use of vacuum prosthesis is often discouraged because of their instability. On the contrary, osseointegrated prosthesis provide stable retention and osseoperception. This cadaveric study evaluated the process of a patient-matched osseointegrated prosthesis for the treatment of thumb amputees. Computed tomography (CT) medical images reconstruction provided information on metacarpal stump, used as input for the parametric screw design. Preoperative planning guided the surgeons in the surgery: postoperative placement confirmed the accuracy of the preoperative planning. Surgeons were directly involved in the implant design to meet their requirements and patient needs. Implants were inserted into cadaveric specimens in one-stage surgery. A similar process can be adopted and exploited for the treatment of different levels of thumb amputations and long finger amputations.

Mechanical and Biological Properties of Titanium and Its Alloys for Oral Implant with Preparation Techniques: A Review

Dental implants have revolutionised restorative dentistry, offering patients a natural-looking and durable solution to replace missing or severely damaged teeth. Titanium and its alloys have emerged as the gold standard among the various materials available due to their exceptional properties. One of the critical advantages of titanium and its alloys is their remarkable biocompatibility which ensures minimal adverse reactions within the human body. Furthermore, they exhibit outstanding corrosion resistance ensuring the longevity of the implant. Their mechanical properties, including hardness, tensile strength, yield strength, and fatigue strength, align perfectly with the demanding requirements of dental implants, guaranteeing the restoration's functionality and durability. This narrative review aims to provide a comprehensive understanding of the manufacturing techniques employed for titanium and its alloy dental implants while shedding light on their intrinsic properties. It also presents crucial proof-of-concept examples, offering tangible evidence of these materials' effectiveness in clinical applications. However, despite their numerous advantages, certain limitations still exist necessitating ongoing research and development efforts. This review will briefly touch upon these restrictions and explore the evolving trends likely to shape the future of titanium and its alloy dental implants.

Active Tactile Sensibility in Implant Prosthesis vs. Complete Dentures: A Psychophysical Study

BACKGROUND AND OBJECTIVES

Proprioceptive information from natural dentition and adjacent oral tissues enables correct masticatory function, avoiding damage to the teeth. Periodontium is the main source of this relevant information, and when a tooth is lost, all this proprioceptive sensibility relies on receptors from muscles, the mucous membrane or the temporomandibular joint, and this sensibility gets worse. Active tactile sensibility measures this proprioceptive capability in microns by psychophysical studies consisting of introducing thin metal foils between patients' dental arches during chewing to see if they are able to notice them or not. Osseoperception is a complex phenomenon that seems to improve this sensibility in patients wearing dental implants. The objective of this investigation is to measure this sensibility in different prosthetic situations by performing a psychophysical investigation.

MATERIAL AND METHODS

We divided 67 patients in three groups depending on their prosthetic situation and performed a psychophysical study by introducing aluminium foils of different thicknesses in order to establish an active tactile sensibility threshold in every group. We also measured variables such as prosthetic wearing time, age or gender to see how they may influence threshold values. We used Student's t-test and Mann-Whitney U tests to analyse these results.

RESULTS

Active tactile sensibility threshold values in implants are lower than those from complete dentures but higher than values in natural dentition. However, values in implants are closer to natural dentition than complete denture values. Age, gender or prosthetic wearing time have no influence in active tactile sensibility thresholds.

CONCLUSION

Active tactile sensibility threshold values depend on prosthetic rehabilitations and the mechanoreceptors involved in every situation. Implant prosthesis presents an increased active tactile sensibility thanks to osseoperception phenomenon.

The role of gingival mechanoreceptors in the tactile function of dental implants

Dental implants seem to restore some degree of tactile function. The aim of this study was to investigate the role of gingival mechanoreceptors in dental-implant osseoperception at the cortical-response level. The gingiva of the upper-left canine implant was stripped off under local anesthesia in five cats. We used intrinsic-signal optical imaging (ISOI) to measure the population-response characteristics of the feline oral-related cortex when separately applying punctate mechanical stimuli to the left canine implant and right intact natural canine. These response characteristics were compared under local anesthesia after removal of the gingiva. Under local anesthesia, the signal strength of the implant was significantly weaker than that of the tooth under weak but not under strong stimulus. After the gingiva was stripped off, the signal strength of the implant was significantly weaker than that of the tooth at all strengths of stimulus. Based on the evoked cortical responses, the gingiva was involved in the maximal tactile function of the implant.

Importance of Osseoperception and Tactile Sensibility during Masticatory Function in Different Prosthetic Rehabilitations: A Review

Background and Objectives: Tactile sensibility is an important characteristic for evaluating the masticatory efficiency in different occlusal situations. When a tooth is extracted, relevant proprioceptors from the periodontal ligament get lost; and after the rehabilitation of this abscess by means of oral prosthesis, this sensibility decreases influencing masticatory function. Osseoperception is a sensitive phenomenon associated with dental implants that allows an increased tactile sensibility to those wearing implant prostheses. The purpose of this study was to determine the difference in tactile sensibility values between implant prosthesis, complete dentures, and natural teeth through a review of the available literature. Materials and Methods. In order to dissect the information, 24 articles from 2004 to 2021 were analyzed from MEDLINE, PubMed Central, and Web of Science databases. These articles were directly related to measuring tactile sensibility in different situations and demonstrating the influence of osseoperception in an improved masticatory function. Results: Tactile sensibility in implant prosthesis is slightly reduced compared with natural dentition but presents improved values with regard to complete dentures. Conclusions: Implant prosthesis are more effective during masticatory function than complete dentures, as they present an increased tactile sensibility, very similar to that present in natural dentition. This enhanced sensibility in implants is due to the osseoperception phenomenon.

Osseoperception following dental implant treatment: a systematic review

OBJECTIVES

Osseoperception is defined as the ability to perceive tactile sensation via mechanoreception in the peri-implant environment. The objective was to systematically review the available literature on the osseoperception phenomenon following dental implant placement and to explore potential factors which might improve the perception capacity.

MATERIAL AND METHODS

A literature search was performed using PubMed, Cochrane, Embase, and Web of Science databases up to June 2021. Both human and animal studies assessing sensory capacity or innervation following implant placement were included in this review. Two reviewers independently performed the study selection, data extraction and quality assessment of the included studies. The methodological quality of the included papers was assessed using Cochrane risk of bias for human studies and SYRCLE's risk of bias tool for animal studies.

RESULTS

The electronic search of databases yielded 1667 results. Following removal of duplicates, title and abstract screening and full-text reading, 22 publications were eligible to be included in the review. Psychophysical evidence from 14 studies indicated a lower tactile function of implants, where active and passive threshold level were found to be 5 and 50 times higher for implants compared to natural teeth, respectively. The neurophysiological evidence from 3 studies indicated cortical plasticity following dental implant placement, measured via trigeminal nerve evoked potentials and functional magnetic resonance imaging. Histological evidence from 5 studies demonstrated the presence of myelinated nerve fibres in the peri-implant tissues. Additionally, immediate implant placement and loading showed beneficial effect on peri-implant tissue (re)innervation, however, no other biological or physiological factors could be identified influencing osseoperception.

CONCLUSIONS

The reported evidence supported the existence of so-called osseoperception phenomenon for restoring the sensory feedback pathway following oral implant rehabilitation. Further studies are required to identify factors that might further assist physiological integration of the oral implants in the human body as such to approach natural oral function.

Evolution of dental implants through the work of per-ingvar branemark: A systematic review

Purpose

This systematic review has been undertaken to highlight the unforgettable contributions of Prof. Brånemark Per-Ingvar (PI). It could be understood that reviewing his work would give an idea of growth of this treatment modality. Materials and Methods: An electronic search on the PubMed/Medline, Ebscohost, and Cochrane database was done using search term "Brånemark PI" to identify his publications. Articles published in English and only related to implants and osseointegration were included. Screening of the titles and abstracts were done according to inclusion criteria and suitable studies were included in the review.

Results

The initial literature search resulted in 187 articles, out of which 92 articles were excluded due to not meeting the inclusion criteria and 16 articles excluded due to non-availability of even abstract also. A total of 79 articles were finally included in this review.

Conclusion

Brånemark PI had a great vision of future; who considered edentulism as equal to amputation and came up with the concept of osseointegrated implants to overcome them. The innovations of Brånemark had assured the world that it is very much possible to provide implant-supported prosthesis in any situations for the rehabilitation of the individuals.

[Effects of platelet-derived growth factor on nerve regeneration around implant in rats]

OBJECTIVE

To investigate the effect of platelet-derived growth factor (PDGF) on nerve regeneration in peri-implant tissues.

METHODS

SD rats with implants in their femurs were injected with PDGF solution. The effects of PDGF on nerve regeneration in peri-implant tissues were analyzed by immunohistochemical staining.

RESULTS

PDGF increased the number of nerve fibers in peri-implant tissues at early stage. PDGF had no significant effect on the number of nerve fibers in peri-implant tissues at late stage. Moreover, these nerves had a typical structure of peripheral nerve fibers.

CONCLUSIONS

PDGF can promote nerve regeneration in peri-implant tissues at early stage. This study provided a certain experimental basis for the clinical application of PDGF to promote nerve regeneration and further improve the sensory function of the implant.

Osseoperception in Dental Implants: A Systematic Review

PURPOSE

Replacement of lost teeth has significant functional and psychosocial effects. The capability of osseointegrated dental implants to transmit a certain amount of sensibility is still unclear. The phenomenon of developing a certain amount of tactile sensibility through osseointegrated dental implants is called osseoperception. The aim of this article is to evaluate the available literature to find osseoperception associated with dental implants.

MATERIALS AND METHODS

To identify suitable literature, an electronic search was performed using Medline and PubMed database. Articles published in English and articles whose abstract is available in English were included. The articles included in the review were based on osseoperception, tactile sensation, and neurophysiological mechanoreceptors in relation to dental implants. Articles on peri-implantitis and infection-related sensitivity were not included. Review articles without the original data were excluded, although references to potentially pertinent articles were noted for further follow-up. The phenomenon of osseoperception remains a matter of debate, so the search strategy mainly focused on articles on osseoperception and tactile sensibility of dental implants. This review presents the histological, neurophysiological, and psychophysical evidence of osseoperception and also the role of mechanoreceptors in osseoperception.

RESULTS

The literature on osseoperception in dental implants is very scarce. The initial literature search resulted in 90 articles, of which 81 articles that fulfilled the inclusion criteria were included in this systematic review.

CONCLUSION

Patients restored with implant-supported prostheses reported improved tactile and motor function when compared with patients wearing complete dentures.

A systematic review on the innervation of peri-implant tissues with special emphasis on the influence of implant placement and loading protocols

OBJECTIVES

To systematically review the available literature on the influence of dental implant placement and loading protocols on peri-implant innervation.

MATERIAL AND METHODS

The database MEDLINE, Cochrane, EMBASE, Web of Science, LILACS, OpenGrey and hand searching were used to identify the studies published up to July 2013, with a populations, exposures and outcomes (PEO) search strategy using MeSH keywords, focusing on the question: Is there, and if so, what is the effect of time between tooth extraction and implant placement or implant loading on neural fibre content in the peri-implant hard and soft tissues?

RESULTS

Of 683 titles retrieved based on the standardized search strategy, only 10 articles fulfilled the inclusion criteria, five evaluating the innervation of peri-implant epithelium, five elucidating the sensory function in peri-implant bone. Three included studies were considered having a methodology of medium quality and the rest were at low quality. All those papers reported a sensory innervation around osseointegrated implants, either in the bone-implant interface or peri-implant epithelium, which expressed a particular innervation pattern. Compared to unloaded implants or extraction sites without implantation, a significant higher density of nerve fibres around loaded dental implants was confirmed.

CONCLUSIONS

To date, the published literature describes peri-implant innervation with a distinct pattern in hard and soft tissues. Implant loading seems to increase the density of nerve fibres in peri-implant tissues, with insufficient evidence to distinguish between the innervation patterns following immediate and delayed implant placement and loading protocols. Variability in study design and loading protocols across the literature and a high risk of bias in the studies included may contribute to this inconsistency, revealing the need for more uniformity in reporting, randomized controlled trials, longer observation periods and standardization of protocols.

Vibrotactile evaluation: osseointegrated versus socket-suspended transfemoral prostheses

This study investigated detection thresholds of vibrometric stimuli in patients with transfemoral amputation supplied with osseointegrated (OI) and socket-suspended prostheses. It included 17 patients tested preoperatively with socket-suspended prostheses and after 2 yr with OI prostheses and a control group (n = 17) using socket-suspended prostheses, evaluated once. Assessments on the prosthetic and intact feet were conducted at six frequencies (8, 16, 32, 64, 125, and 250 Hz). Furthermore, measurements were conducted to investigate how vibrometric signals are transmitted through a test prosthesis. The results showed that the OI group had improved ability to detect vibrations through the prosthesis at 125 Hz (p = 0.01) at follow-up compared with the preoperative measurement. Compared with the control group, the OI group at follow-up had better ability to detect high frequency vibrations through the prosthesis (125 Hz, p = 0.02; 250 Hz, p = 0.03). The vibrometric signal transmitted through the test prosthesis was reduced at 8, 125, and 250 Hz but was amplified at 16, 32, and 64 Hz. Differences between the OI and the control groups were found in the highest frequencies in which the test prosthesis showed reduction of the vibrometric signal. The study provides insight into the mechanisms of vibration transmission between the exterior and bone-anchored as well as socket-suspended amputation prostheses.

Visualization analysis of research frontiers and trends in nerve regeneration and osseoperception in the repair of tooth loss

This study analyzed 85 articles indexed by the Web of Science concerning nerve regeneration and osseoperception during tooth loss repair. Using the Web of Science database and Citespace III software, a document co-citation network map was drawn by document co-citation analysis and word frequency analysis methods. Combined with emergent node secondary literature retrieval, subject headings with apparent changing word frequency trends were retrieved so as to identify research frontiers and development trends. Research frontiers and hotspots for neuronal calcium sensor protein were quantitatively explored to forecast future research developments in nerve regeneration and osseoperception during repair of tooth loss.

Active tactile sensibility of single-tooth implants versus natural dentition: a split-mouth double-blind randomized clinical trial

BACKGROUND

Unlike passive sensitivity of implants/teeth that is assessed more, only three controversial studies have compared active tactile sensibility (ATS) of implants and teeth.

PURPOSE

We aimed to explore the difference between the ATS of teeth and single-tooth implants.

METHODS

The ATS of single-tooth implants and contralateral teeth was measured in 25 patients after they bit on gold and placebo foils 0- to 70-μm thick, each for five times, in a random order blinded to patients and assessor, carried out at two sessions. Based on the experimental range of 0 μm (mock trials) to 70 μm, the sigmoid shape of psychometric curve was estimated to locate the 50% values as the ATS thresholds for each tooth or implant. ATS Data were analyzed using paired and unpaired t-tests and multiple linear regression (α = 0.05, β ≤ 0.1). Also, equivalence testing approach was used to assess semi-objectively the clinical significance.

RESULTS

Average ATS values for teeth and implants were 21.4 ± 6.55 μm and 30.0 ± 7.55 μm, respectively (p = .0001 [paired t-test]). None of the geometric characteristics of implants nor duration of implant in function were correlated with the ATS (p > .4 [regression]). Age was positively associated with the ATS of both implants and teeth (p ≤ .019 [regression]). Tooth ATS (but not implant ATS) was significantly higher in males compared with females (p = .050 [unpaired t-test]), which contributed to a generalizable tooth-implant difference higher than 8-μm clinical equivalence margin in females. The ATS was not significantly different between arches or between anterior/posterior regions (p > .6).

CONCLUSION

There was a slight but statistically significant difference between implant and tooth tactile sensitivities.

A novel bionic design of dental implant for promoting its long-term success using nerve growth factor (NGF): utilizing nano-springs to construct a stress-cushioning structure inside the implant

The absence of periodontium causes masticatory load in excess of the self-repairing potential of peri-implant bone; peri-implant bone loss caused by occlusal overload is not uncommon in patients and greatly diminishes chances of long-term success. Regenerative treatments may be useful in inducing peri-implant bone regeneration, but are only stopgap solutions to the aftermaths caused by the imperfect biomechanical compatibility of the dental implant. Despite promising success, the tissue-engineered periodontal ligament still needs a period of time to be perfected before being clinically applied. Hence, we propose a novel design of dental implant that utilizes nano-springs to construct a stress-cushioning structure inside the implant. Many studies have shown that NGF, a neurotrophin, is effective for nerve regeneration in both animal and clinical studies. Moreover, NGF has the potential to accelerate bone healing in patients with fracture and fracture nonunion and improve osseointegration of the implant. The key point of the design is to reduce stress concentrated around peri-implant bone by cushioning masticatory forces and distributing them to all the peri-implant bone through nano-springs, and promote osseoperception and osseointegration by NGF-induced nerve regeneration and new bone formation. This design, which transfers the main biomechanical interface of the implant from outside to inside, if proven to be valid, may to some extent compensate for the functions of lost periodontium in stress cushioning and proprioception.