Nuove frontiere in implantologia e rigenerazione ossea in campo odontoiatrico

The work focused on bone regeneration, membranes and implant surfaces in dentistry. Starting from a clinical need widely shared in the dental field such as that of guided bone regeneration, were studied the development of biomaterials, membranes and implant surfaces. As for the biomaterials, were first analyzed the characteristics of autologous samples. The samples were stored at different time intervals and processed for analysis of cell viability, protein synthesis and gene expression. The results show how the preservation prolonged periods in conditions ex vivo induces an increased synthesis of inflammatory proteins such as TNF-α. Was recreated in an animal model a situation of sheep bone regeneration in the presence of TNF-α, indicating that such a state causes a slowdown in new bone formation also in qualitative terms. Within the study of biomaterials have been studied different decellularization protocols for withdrawals heterologous bone. Later in vitro and animal model was used to evaluate the bone substitutes trade enriched with stem cells (SC). On the dog has been employed a biomaterial enriched in stem cell associated with dental implant. It was found that at sites enriched with SC has taken place better bone integration. On ovine model were performed in which the maxillary sinus lifts have tested other materials enriched with SC or less in order to investigate the presence of different cell populations and the ability of the anti-inflammatory SC. In sites with SC healing and formation of new bone matrix appear to be more rapid and more moderate inflammatory reaction. Were also carried out studies of biocompatibility of synthetic bone substitutes. Regarding the membranes were developed and tested in vitro different decellularization protocols for treat membranes developed from bovine pericardium. Later the same have been tested in vivo mouse model. In parallel has been studied in vitro a synthetic membrane of polyethylene glycol with MTT assay and with arrays for genetic control. The results show be sure the application and PCR confirmation cell differentiation osteoblastic and endothelial. About dental implants has been studied a new implant surface ionized and treated with SC. These tests were performed in vitro and PCR tests to investigate the type of protein that was developed in contact with the surface. This treatment allows a greater cell proliferation, a higher cell differentiation with cells that adhere with good osteocitary morphology and that are genetically stable

Platform switching on wide-diameter external hex implants a finite element analysis

Objectives: The objective of this work was to use finite element analysis to compare the effect of forces coming to bear on abutments 4.1 or 5.0 mm in diameter connected to a 5.0 mm implant (i.e. with or without platform swit - ching). Study design: A 3D CAD model of a 5 x 11.5 mm external hex implant was developed, complete with a connection screw and either of two abutments, one 4.1 and the other 5 mm in diameter, to assess the influence of two loading conditions, i.e. 200 N loaded either axially or off center on the top of the abutment. Results and conclusions: In the symmetrically loaded models, greater stresses were transmitted to the bone in the area below the neck of the implant in the case of the wider-diameter abutment. When the narrower abutment was considered, the stress lines remained confined to the metal and were transferred to the bone in a more distal position. When the stresses in the bone where compared under non-symmetrical loading of the larger- and smaller-diameter abutments, the stresses reached lower values in the latter case. These findings indicate that platform switching (i.e. coupling a 4.1 mm abutment with a 5 mm implant) achieves a better, more even distribution of the peri-implant stresses deriving from simulated occlusal loads on the bone margins

Decellularization and Delipidation Protocols of Bovine Bone and Pericardium for Bone Grafting and Guided Bone Regeneration Procedures

The combination of bone grafting materials with guided bone regeneration (GBR) membranes seems to provide promising results to restore bone defects in dental clinical practice. In the first part of this work, a novel protocol for decellularization and delipidation of bovine bone, based on multiple steps of thermal shock, washes with detergent and dehydration with alcohol, is described. This protocol is more effective in removal of cellular materials, and shows superior biocompatibility compared to other three methods tested in this study. Furthermore, histological and morphological analyses confirm the maintenance of an intact bone extracellular matrix (ECM). In vitro and in vivo experiments evidence osteoinductive and osteoconductive properties of the produced scaffold, respectively. In the second part of this study, two methods of bovine pericardium decellularization are compared. The osmotic shock-based protocol gives better results in terms of removal of cell components, biocompatibility, maintenance of native ECM structure, and host tissue reaction, in respect to the freeze/thaw method. Overall, the results of this study demonstrate the characterization of a novel protocol for the decellularization of bovine bone to be used as bone graft, and the acquisition of a method to produce a pericardium membrane suitable for GBR applications

Nuove frontiere in implantologia e rigenerazione ossea in campo odontoiatrico

The work focused on bone regeneration, membranes and implant surfaces in dentistry. Starting from a clinical need widely shared in the dental field such as that of guided bone regeneration, were studied the development of biomaterials, membranes and implant surfaces. As for the biomaterials, were first analyzed the characteristics of autologous samples. The samples were stored at different time intervals and processed for analysis of cell viability, protein synthesis and gene expression. The results show how the preservation prolonged periods in conditions ex vivo induces an increased synthesis of inflammatory proteins such as TNF-α. Was recreated in an animal model a situation of sheep bone regeneration in the presence of TNF-α, indicating that such a state causes a slowdown in new bone formation also in qualitative terms. Within the study of biomaterials have been studied different decellularization protocols for withdrawals heterologous bone. Later in vitro and animal model was used to evaluate the bone substitutes trade enriched with stem cells (SC). On the dog has been employed a biomaterial enriched in stem cell associated with dental implant. It was found that at sites enriched with SC has taken place better bone integration. On ovine model were performed in which the maxillary sinus lifts have tested other materials enriched with SC or less in order to investigate the presence of different cell populations and the ability of the anti-inflammatory SC. In sites with SC healing and formation of new bone matrix appear to be more rapid and more moderate inflammatory reaction. Were also carried out studies of biocompatibility of synthetic bone substitutes. Regarding the membranes were developed and tested in vitro different decellularization protocols for treat membranes developed from bovine pericardium. Later the same have been tested in vivo mouse model. In parallel has been studied in vitro a synthetic membrane of polyethylene glycol with MTT assay and with arrays for genetic control. The results show be sure the application and PCR confirmation cell differentiation osteoblastic and endothelial. About dental implants has been studied a new implant surface ionized and treated with SC. These tests were performed in vitro and PCR tests to investigate the type of protein that was developed in contact with the surface. This treatment allows a greater cell proliferation, a higher cell differentiation with cells that adhere with good osteocitary morphology and that are genetically stable.Il lavoro si è focalizzato sulla rigenerazione ossea, le membrane e le superfici implantari in campo odontoiatrico. Partendo da una necessità clinica ampiamente condivisa nel settore odontoiatrico come quella della rigenerazione ossea guidata a fini implantologici, è seguito lo sviluppo di biomateriali, di membrane e di superfici implantari. Per quanto riguarda i biomateriali sono state prima di tutto analizzate le caratteristiche di prelievi autologhi. I campioni raccolti sono stati conservati a diversi intervalli di tempo e processati per analisi di vitalità cellulare, sintesi proteica e per l’espressione genica. Dai risultati emerge come la conservazione a tempi prolungati in condizioni ex vivo induca un aumento della sintesi di proteine infiammatorie come il TNF-α. E’ stato ricreato in un modello animale ovino una situazione di rigenerazione ossea in presenza di TNF-α indicando che tale stato induce un rallentamento nella formazione di nuovo osso anche in termini qualitativi. Nell’ambito dello studio dei biomateriali sono stati studiati differenti protocolli di decellularizzazione per prelievi di osso eterologo. Successivamente in vitro e su modello animale si sono valutati dei sostituti ossei del commercio arricchiti con cellule staminali (SC). Sul cane è stato impiegato un biomateriale arricchito di cellule staminali associato ad impianto dentale. Ne è emerso che nei siti arricchiti con SC sia avvenuta una migliore integrazione. Su modello ovino sono stati effettuati rialzi del seno mascellare in cui si sono testati altri materiali arricchiti o meno con SC al fine di indagare la differente presenza di popolazioni cellulari e la capacità antinfiammatoria delle SC. Nei siti con presenza di SC la guarigione e la formazione di nuova matrice ossea appaiono più rapide e la reazione infiammatoria più contenuta. Sono stati inoltre effettuati studi di biocompatibilità di sostituti ossei sintetici. Riguardo le membrane sono stati sviluppati e testati in vitro differenti protocolli di decellularizzazione per il tattamento di membrane sviluppate da pericardio bovino. Successivamente le stesse sono state testate in vivo su modello murino. Parallelamente è stata studiata in vitro una membrana sintetica di polietilene glicole con test MTT e con array per il controllo genetico. I risultati dimostrano esserne sicura l’applicazione e la PCR conferma il differenziamento cellulare in senso osteoblastico ed endoteliale. Riguardo gli impianti dentali è stata studiata una nuova superficie implantare ionizzata e trattata con SC. Sono stati effettuati test in vitro e test PCR per indagare la tipologia di proteine che si sviluppava a contatto con la superficie. Tale trattamento consente una maggiore proliferazione cellulare, un maggior differenziamento cellulare con cellule che aderiscono con buona morfologia osteocitaria e che sono geneticamente stabili

Managing the Peri-implant Mucosa: A Clinically Reliable Method for Optimizing Soft Tissue Contours and Emergence Profile

STATE OF THE PROBLEM: The proper representation of soft tissue contours for a natural aspect of the peri-implant mucosa and its mimesis with the adjacent teeth is a crucial aspect of the esthetic area restoration. PURPOSE: This paper describes a method for the easy transfer of the peri-implant tissue morphology onto impression material with a view to achieving an accurate, custom implant restoration. The procedure described is suitable both for single and multi-unit implant-supported prostheses. CLINICAL PROCEDURES: Once the peri-implant mucosa is sculpted by the provisional restoration, the emergence profile is duplicated. The implant analog is embedded into laboratory stone or plaster in a mixing cup and allowed to set. The provisional restoration is removed from the oral cavity and screwed to the implant analog; then, a polyether material is placed in the mixing cup so that the provisional restoration is put into impression material at the level of the prosthetic emergence profile. After the polyether polymerizing, the provisional prosthesis is unscrewed and replaced with the stock hexed transfer for the final impression. Next, cold self-curing resin is poured into this gap and left to set. A custom transfer for this single implant site is thus obtained. This modified transfer is then removed and screwed onto the implant in the oral cavity for the definitive impression. CONCLUSIONS: The technique described enables a faithful reproduction of the peri-implant soft tissues and emergence profile. CLINICAL SIGNIFICANCE: An emergence profile that mimics the natural tooth should be obtained by successful esthetic implant restoration. Moreover, it allows proper hygiene, which is fundamental for implant maintenance. The best way to achieve the correct emergence profile is to sculpture the peri-implant mucosa by means of a provisional prosthesis. Prefabricated provisional crowns cannot mimic the complexity and the variations of human soft tissue. Therefore, only a chair-side modification of the provisional restoration can accomplish the optimal result. Such a requirement can be satisfied by the clinical method described in the present report

Accuracy of 3D digital modeling of dental arches

ABSTRACT Objective: The aim of the study was to verify and compare the accuracy of full-arch digital impressions obtained using two intraoral scanners and three scanning methodologies. Methods: A resin model created with dental 3-D printing was scanned by a reference scanner (Zfx Evolution - Zimmer Biomet, Palm Beach Gardens, FL) in order to obtain a 3D reference; the same resin model was then scanned with two different intraoral scanners (Zfx IntraScan and Carestream 3600 - CS 3600®, Carestream, Rochester, NY, USA) using: Technique A (from tooth #27 up to tooth #17); Technique B (from tooth #11 up to tooth #17 and then from tooth #21 up to tooth #27) and Technique C (from tooth #22 up to tooth #17, and then from tooth #12 up to tooth #27 - the MeshLab software v. 1.3.3 was then used to match the two scans). The scans obtained were superimposed over the reference scan by means of a software, and the volumetric discrepancies were calculated. Results: The mean results for the Zfx Intrascan scanner were: Technique A = 302.47 ± 37.42 µm; Technique B = 180.45 ± 29.86 µm; Technique C = 147.34 ± 28.23 µm. The mean results for the Carestream 3600 scanner were: Technique A = 303.59 ± 40.20 µm; Technique B = 181.53 ± 29.61 µm; Technique C = 142.28 ± 35.33 µm. Technique C, used by both scanners, produced less volumetric discrepancies compared to the other techniques. Conclusions: The scanning technique had a statistically significant effect on the quality of the scan (p< 0.0001), whereas the scanner did not present any significant influence (p= 0.91)

Selection of Collagen Membranes for Bone Regeneration: A Literature Review

Several treatment modalities have been proposed to regenerate bone, including guided bone regeneration (GBR) where barrier membranes play an important role by isolating soft tissue and allowing bone to grow. Not all membranes biologically behave the same way, as they differ from their origin and structure, with reflections on their mechanical properties and on their clinical performance. Collagen membranes have been widely used in medicine and dentistry, because of their high biocompatibility and capability of promoting wound healing. Recently, collagen membranes have been applied in guided bone regeneration with comparable outcomes to non-resorbable membranes. Aim of this work is to provide a review on the main features, application, outcomes, and clinical employment of the different types of collagen membranes. Comparisons with non-resorbable membranes are clarified, characteristics of cross-linked collagen versus native collagen, use of different grafting materials and need for membrane fixation are explored in order to gain awareness of the indications and limits and to be able to choose the right membrane required by the clinical condition

Five-year prospective study on conometric retention for complete fixed prostheses

To evaluate the reliability of a conometric system for fixed retention of complete prostheses (CPs) on four implants after 5 years of function

Medication-related osteonecrosis of the jaw and dental implants failures: a systematic review

No well-established evidences supporting the safe use of Bisphosphonates (BPs) or others antiresorptive agents prior, during or after dento-alveolar surgery, are currently available; moreover, the real risk of osteonecrosis of the jaw (ONJ) development is still unknown. The aim of the present systematic review was to assess the scientific literature concerning the implants placement in antiresorptive agents-users and the related risk of implants failure and ONJ development. English papers published from January 2003 until December 2014 were identified on Medline database. Titles and abstracts retrieved form electronic search were screened separately by two examiners; thus, original studies dealing with dental implants placement during or before bone antiresorptive agents therapy, and the relative risk of implant failure or development of osteonecrosis were evaluated. Due to the heterogeneity of the included studies and the high risk of bias, there is no evidence of the safe use of oral antiresorptive agents prior or after dental implant surgery. Indeed, implant failure and ONJ development can occur and represent a devastating side effect that should be considered during the treatment. Within the limitation of the present systematic review, high quality studies are needed to provide an adequate level of evidence regarding the safety of dento-alveolar surgery during or before bone resorption inhibition therapy, and the increase predisposition to osteonecrosis of the jaw (ONJ) development. Therefore, antiresorptive agents therapy should be considered a risk factor until further evidence is prospectively obtained

Evaluation of root coverage with and without connective tissue graft for the treatment of single maxillary gingival recession using an image analysis system: a randomized controlled clinical trial

The aim of this prospective randomized clinical study was to evaluate, by means of an image analysis system, the efficacy of two different surgical procedures for the treatment of Miller Class I and II maxillary gingival recession. Patients treated for maxillary gingival recession were recruited and randomly divided into two groups: patients who received a coronally advanced flap with connective tissue graft (CAF + CTG) or CAF alone. Outcome parameters included complete root coverage, recession reduction, and keratinized tissue amount. Twenty-five patients completed the 12-month follow-up period. Patients in the CAF + CTG group showed a better primary outcome- gingival recession at 12 months-than CAF patients (P = .0001). Gingival recession at 12 months had a median of 0.5 (interquartile range [IQR] 0.5 to 0.6) in the CAF + CTG group and a median of 1.0 (IQR 0.9 to 1.1) in the CAF group. CAF + CTG and CAF groups had similar complete root coverage at 6 and 12 months. Recession and keratinized tissue width significantly decreased over time (P < .0001), with no effect of treatment or of treatment over time. Buccal probing depth had similar values over time (P = .28) and in the two groups (P = .52). Buccal clinical attachment level had similar values in the two groups (P = .87); moreover, mesial and distal clinical attachment levels did not show any variation over time (P = .88 and P = .68, respectively). By means of a computerized image analysis system better outcomes in terms of recession reduction after 12 months of follow-up were measured for maxillary gingival recessions treated with CAF and CTG. Adjunctive application of a CTG under a CAF increased the probability of achieving complete root coverage in maxillary Miller Class I and II defects (61.5% versus 83.3%; P = .38). Both treatments were equally effective in providing a consistent reduction of the baseline recession