Polishing methods for composites restoration: the influence on human gingival fibroblasts behaviour.

BACKGROUND: Carious/Non-carious cervical lesions with gingival recessions may require both dental and periodontal reconstructive therapy, where flaps/grafts may be placed in contact with a dental filling material. Human Gingival Fibroblasts (HGF-1) response during the early phase of healing could vary according to the procedures employed to cure the dental composite. Moreover, oxygen diffusion into dental composite inhibits the polymerization reaction, creating an oxygen-inhibited layer (OIL) that presents residual unreacted monomers. The aim of this study was to assess the effect of different polishing techniques and OIL on HGF-1. METHODS: Composite discs polished with different techniques (diamond rubber, abrasive discs and tungsten carbide burr) were used. An additional not polished smooth group obtained with and without OIL was used as control. Samples were physically characterized through the analysis of their hydrophilicity and surface topography through contact angle measurement and SEM, respectively; afterwards the biologic response of HGF-1 when cultured on the different substrates was analyzed in terms of cytotoxicity and gene expression. RESULTS: The finishing systems caused alterations to the wettability, even if without a proportional relation towards the results of the proliferation essay, from which emerges a greater proliferation on surfaces polished with one-step diamond rubber and with abrasive discs as well as a direct effect of the glycerin layer, confirming that surface roughness can heavily influence the biological response of HGF-1. CONCLUSIONS: Surfaces wettability as well as cellular behavior seem to be affected by the selection of the finishing system used to lastly shape the restoration. Especially, the presence of OIL act as a negative factor in the regards of human gingival fibroblasts. The present study may provide the first clinical instruction regarding the best polishing system of composite material when the restoration is placed directly in contact with soft tissue cells. Understanding HGF-1 behavior can help identifying the polishing treatment for direct restoration of carious/non-carious cervical lesions associated with gingival recessions.

Composite PCL Scaffold With 70% ß-TCP as Suitable Structure for Bone Replacement.

OBJECTIVES: The purpose of this work was to optimise printable polycaprolactone (PCL)/ß-tricalcium phosphate (ß-TCP) biomaterials with high percentages of ß-TCP endowed with balanced mechanical characteristics to resemble human cancellous bone, presumably improving osteogenesis. METHODS: PCL/ß-TCP scaffolds were obtained from customised filaments for fused deposition modelling (FDM) 3D printing with increasing amounts of ß-TCP. Samples mechanical features, surface topography and wettability were evaluated as well as cytocompatibility assays, cell adhesion and differentiation. RESULTS: The parameters of the newly fabricated materila were optimal for PCL/ß-TCP scaffold fabrication. Composite surfaces showed higher hydrophilicity compared with the controls, and their surface roughness sharply was higher, possibly due to the presence of ß-TCP. The Young's modulus of the composites was significantly higher than that of pristine PCL, indicating that the intrinsic strength of ß-TCP is beneficial for enhancing the elastic modulus of the composite biomaterials. All novel composite biomaterials supported greater cellular growth and stronger osteoblastic differentiation compared with the PCL control. CONCLUSIONS: This project highlights the possibility to fabricat, through an FDM solvent-free approach, PCL/ß-TCP scaffolds of up to 70 % concentrations of ß-TCP. overcoming the current lmit of 60 % stated in the literature. The combination of 3D printing and customised biomaterials allowed production of highly personalised scaffolds with optimal mechanical and biological features resembling the natural structure and the composition of bone. This underlines the promise of such structures for innovative approaches for bone and periodontal regeneration.

Preparation of human primary macrophages to study the polarization from monocyte-derived macrophages to pro- or anti-inflammatory macrophages at biomaterial interface in vitro.

Background/purpose: Testing of dental materials when in contact with innate immune cells has been so far hindered by the lack of proper in vitro models. Human primary monocyte-derived macrophages (MDMs) would be an excellent option to this aim. However, the inability to detach them from the tissue culture plates contrast the possibility to culture them on biomaterials. The goal of the present work is to present and validate an innovative protocol to obtain MDMs from peripheral blood monocytes, and to reseed them in contact with biomaterials without altering their viability and phenotype. Materials and methods: We differentiated MDMs on ultra-low attachment tissue culture plastics and recovered them with specific detachment solution in order to be reseeded on a secondary substrate. Therefore, using biological assays (RT-PCR, Western blot, and immunofluorescence) we compared their phenotype to MDMs differentiated on standard culture plates. Results: Transferred MDMs keep their differentiated M0 resting state, as well as the ability to be polarized into M1 (pro-inflammatory) or M2 (anti-inflammatory) macrophages. Conclusion: These data provide the dental material research community the unprecedented possibility to investigate the immunomodulatory properties of biomaterials for dental application.

Aptamer-enriched scaffolds for tissue regeneration: a systematic review of the literature.

Introduction: Aptamers are a brand-new class of receptors that can be exploited to improve the bioactivity of tissue engineering grafts. The aim of this work was to revise the current literature on in vitro and in vivo studies in order to i) identify current strategies adopted to improve scaffold bioactivity by aptamers; ii) assess effects of aptamer functionalization on cell behavior and iii) on tissue regeneration. Methods: Using a systematic search approach original research articles published up to 30 April 2022, were considered and screened. Results: In total, 131 records were identified and 18 were included in the final analysis. Included studies showed that aptamers can improve the bioactivity of biomaterials by specific adsorption of adhesive molecules or growth factors from the surrounding environment, or by capturing specific cell types. All the studies showed that aptamers ameliorate scaffold colonization by cells without modifying the physicochemical characteristics of the bare scaffold. Additionally, aptamers seem to promote the early stages of tissue healing and to promote anatomical and functional regeneration. Discussion: Although a metanalysis could not be performed due to the limited number of studies, we believe these findings provide solid evidence supporting the use of aptamers as a suitable modification to improve the bioactivity of tissue engineering constructs.

A Novel Self-Assessment Method for Training Access Cavity on 3D Printed Endodontic Models.

BACKGROUND: New technologies can facilitate the transition from pre-clinical to clinical settings. We investigate students' satisfaction with a novel learning method adopted in access cavity exercises. METHODS: Students performed their access cavity on inexpensive, in-house 3D printed teeth. Their performances were evaluated by scanning the prepared teeth with an intraoral scanner and visualized using a mesh processing software. Then, the same software was used to align the tooth prepared by the student and the teacher's one for self-assessment purposes. Students were asked to answer a questionnaire about their experiences with this new learning method. RESULTS: From the teacher's perspective, this novel learning approach was easy, straightforward and affordable. Overall, student feedback was positive: 73% found that access cavity assessment by scanning was more useful compared to a visual inspection under magnification and 57% reported that they had a better understanding of errors and mishaps. On the other hand, students pointed out that the material used to print teeth was too soft. CONCLUSION: The use of in-house 3D printed teeth in pre-clinical training is a simple way to overcome some of the drawbacks associated with extracted teeth, such as limited availability, variability, cross-infection control, and ethical constraints. The use of intraoral scanners and mesh processing software could improve student self-assessment.

Predictability of intraoral scanner error for full-arch implant-supported rehabilitation.

OBJECTIVES: The present study aimed to analyze the behaviors of three intraoral scanners (IOSs): evaluating the interdistance and axial inclination discrepancies in full-arch scans, predictable errors were searched. MATERIALS AND METHODS: Six edentulous sample models with variable numbers of dental implants were used; reference data were obtained with a coordinate-measuring machine (CMM). Each IOS (i.e., Primescan, CS3600, and Trios3) performed 10 scans per model (180 total scans). The origin of each scan body was used as a reference point to measure interdistance lengths and axial inclinations. Precision and trueness of interdistance measurements and axial inclinations were evaluated to address error predictability. Bland-Altman analysis, followed by linear regression analysis and Friedman's test (plus Dunn's post hoc correction), was performed to evaluate the precision and trueness. RESULTS: Regarding interdistance, Primescan showed the best precision (mean ± SD: 0.047 ± 0.020 mm), while Trios3 underestimated the reference value more than the others (p < 0.001) and had the worst performance (mean ± SD: -0.079 ± 0.048 mm). Concerning the inclination angle, Primescan and Trios3 tended to overestimate angle values, while CS3600 underestimated them. Primescan had fewer inclination angle outliers, but it tended to add 0.4-0.6° to the measurements. CONCLUSIONS: IOSs showed predictable errors: they tended to overestimate or underestimate linear measurements and axial inclinations of scan bodies, one added 0.4-0.6° to the angle inclination values. In particular, they showed heteroscedasticity, a behavior probably related to the software or the device itself. CLINICAL SIGNIFICANCE: IOSs showed predictable errors that could affect clinical success. When performing a scan or choosing a scanner, clinicians should clearly know their behaviors.

Testosterone Enanthate: An In Vitro Study of the Effects Triggered in MG-63 Cells.

The aim of this study was to investigate the effects of the androgenic hormone testosterone enanthate (TE) on human MG-63 cells. MG-63 were cultured for 24 h in the presence of TE at increasing concentrations to assess its lethal dose. Therefore, the suitable concentration for a prolonged use of TE in vitro was assessed by viability assay over 9 days. Finally, MG-63 were exposed to TE for 14 days and assayed for differentiation by qPCR and Alizarin Red S staining. TE in the amount of 100 µM resulted as the maximum dose tolerated by MG-63 cells after 24 h. However, a prolonged exposure in culture TE in the amount of 100 µM showed a cytostatic effect on cell proliferation. On the contrary, TE 10 µM was tolerated by the cells and did not boost cell proliferation, but did enhance new bone formation, as revealed by COL1A1, ALPL, BGLAP, and IBSP gene expression after 3, 7, and 14 days, and calcium deposition by Alizarin Red S staining after 14 days. Based on the current study, 10 µM is the critical dose of TE that should be used in vitro to support bone differentiation of MG-63 cells.

The effect of a 2-mm inter-implant distance on esthetic outcomes in immediately non-occlusally loaded platform shifted implants in healed ridges: 12-month results of a randomized clinical trial.

BACKGROUND: Three millimeter is considered as the minimum distance to obtain soft and bone tissue stability in case of adjacent implants. The possibility to preserve peri-implant bone level using a platform switching connection has questioned this concept. PURPOSE: The study evaluates soft tissue maintenance and marginal bone stability around implants, placed at 2 or 3 mm of distance. MATERIALS AND METHODS: Thirty patients received two immediately loaded implants either at 2-mm (test) or at 3-mm (control) of distance in the premolar area. Soft tissue esthetics (papilla height and fill, keratinized tissue, recession) and radiographic peri-implant bone level changes were measured at 3, 6, and 12 months. RESULTS: No significant differences between the two groups were detected neither for all soft tissue esthetic outcomes nor for bone level modifications up to 12 months. CONCLUSION: The results suggested that up to 12 months post-loading, both 2- and 3-mm inter-distance platform-switched implants in healed site, supported adequate esthetic outcomes and peri-implant bone stability.

Thermal-induced hydrophilicity enhancement of titanium dental implant surfaces.

Titanium surface characteristics, including microtopography, chemical composition, and wettability, are essential features to achieve osseointegration of dental implants, but the choice of a particular surface topography is still a debated topic among clinicians. An increased level of implant surface hydrophilicity has been demonstrated to ameliorate osseointegration and shorten healing times. The aim of this work is to develop and test a suitable thermal-based method to enhance titanium surface wettability without modifying other characteristics of the implant surface. For this function, titanium discs with different surface topography have been thermally treated by testing different temperatures and excluding those that led to evident chromatic and morphological modifications. The selected surface gain in wettability after the treatment was assessed through contact angle measurement, chemistry modifications through x-ray photoelectron spectroscopy (XPS) analysis, and microtopography through scanning electron microscopy (SEM). Results showed a great enhancement in hydrophilicity on the tested surfaces without any other modification in terms of surface chemical composition and topography. A possible limitation of this method could be the persistent, although relatively slow, biological aging of the surfaces after the treatment. The present findings indicate that the described treatment could be a safe and effective method to enhance dental titanium hydrophilicity and thus its biological performance.

A glance on the role of fibronectin in controlling cell response at biomaterial interface.

The bioactivity of biomaterials is closely related to cell response in contact with them. However, shortly after their insertion, materials are soon covered with proteins that constitute the biological fluids, and which render the direct surface recognition by cells almost impossible. The control of protein adsorption at the interface is therefore desirable. Extracellular matrix proteins are of particular interest in this sense, due to their well-known ability to modulate cell behavior. Particularly, fibronectin plays a leading role, being present in both healthy and injured tissues undergoing healing and regeneration. The aim of the present work is to give an overview on fibronectin and on its involvement in the control of cell behavior providing evidence of its pivotal role in the control of cell adhesion, spreading, migration, proliferation and differentiation. A deep insight into methods to enrich biomaterials surface with fibronectin will be then discussed, as well as new cues on the possibility to design tailored platforms able to specifically retain fibronectin from the surrounding extracellular milieu.

Thermal treatment to increase titanium wettability induces selective proteins adsorption from blood serum thus affecting osteoblasts adhesion.

OBJECTIVES: To investigate how a thermal treatment to increase titanium wettability influences proteins adsorption from blood serum and osteoblasts responses. METHODS: Titanium discs with machined or micro-rough profiles were thermally treated to obtain hydrophilic surfaces. The adsorption kinetics of two representative serum proteins were determined by Bradford assay, while the stable protein adsorption pattern from blood serum was investigated by SDS-PAGE and Western Blot analysis. Subsequently, MC3T3-E1 cells were cultured on titanium for 24h and assayed for adhesion and morphology. RESULTS: Thermally-induced hydrophilicity dramatically improved the capacity of titanium to selectively adsorb fibronectin and fibrinogen from blood serum, without evident influence on other representative serum proteins. The selective adsorption of fibronectin was linked to the improved capacity of MC3T3-E1 cells to adhere and spread on hydrophilic surfaces. SIGNIFICANCE: We identified a potential method to improve selective protein adsorption on titanium by enhancing implant surface wettability through a thermal treatment. Selective fibronectin adsorption was further indicated as the responsible for improved osteoblasts adhesion. Targeting specific cell response by selective protein adsorption appears to be crucial to conceive even more performant therapies.

Plasma Proteins at the Interface of Dental Implants Modulate Osteoblasts Focal Adhesions Expression and Cytoskeleton Organization.

The host-material interface is a crucial relationship dictating the possibility of successful osseointegration in implant dentistry. The aim of the present study was to characterize the effects of plasma proteins pre-adsorption on the adhesion capacity of osteoblasts, which occurs immediately after implant insertion in vivo. After having pre-adsorbed human plasma proteins on a machined and microrough titanium surface, MC3T3-E1 osteoblasts adhesion was evaluated through crystal violet cell adhesion assay, immunofluorescence staining for cytoskeleton, focal adhesions and cell nuclei, and scanning electron microscopy. The pre-adsorbed protein layer markedly affected the adhesion rate of cells, as well as their morphology and the expression of focal contacts. Moreover, protein adsorption to the underlying titanium surface was found to be correlated to surface pre-wetting. Thus, the early adsorption of serum proteins to the interface of dental implants impacts cell adhesion in terms of strength and of focal adhesions expression.

Is selective protein adsorption on biomaterials a viable option to promote periodontal regeneration?

Periodontitis is an inflammatory condition that can induce significant destruction of the periodontium, the set of specialized tissues that provide nourishment and support to the teeth. According to the guided tissue regeneration principles, the periodontium can be regenerated if the spatiotemporal control of wound healing is obtained, namely the tune control of cell response. After material implantation, protein adsorption at the interface is the first occurring biological event, which influences subsequent cell response. With the regard of this, we hypothesize that the control of selective adsorption of biological cues from the surrounding milieu may be a key-point to control selective cell colonization of scaffolds for periodontal tissue regeneration.

Stanozolol promotes osteogenic gene expression and apposition of bone mineral in vitro

Abstract Stanozolol (ST) is a synthetic androgen with high anabolic potential. Although it is known that androgens play a positive role in bone metabolism, ST action on bone cells has not been sufficiently tested to support its clinical use for bone augmentation procedures. Objective: This study aimed to assess the effects of ST on osteogenic activity and gene expression in SaOS-2 cells. Material and Methods: SaOS-2 deposition of mineralizing matrix in response to increasing doses of ST (0-1000 nM) was evaluated through Alizarin Red S and Calcein Green staining techniques at 6, 12 and 24 days. Gene expression of runt-related transcription factor 2 (RUNX2), vitamin D receptor (VDR), osteopontin (SPP1) and osteonectin (ON) was analyzed by RT-PCR. Results: ST significantly influenced SaOS-2 osteogenic activity: stainings showed the presence of rounded calcified nodules, which increased both in number and in size over time and depending on ST dose. RT-PCR highlighted ST modulation of genes related to osteogenic differentiation. Conclusions: This study provided encouraging results, showing ST promoted the osteogenic commitment of SaOS-2 cells. Further studies are required to validate these data in primary osteoblasts and to investigate ST molecular pathway of action.

Stanozolol promotes osteogenic gene expression and apposition of bone mineral in vitro.

Stanozolol (ST) is a synthetic androgen with high anabolic potential. Although it is known that androgens play a positive role in bone metabolism, ST action on bone cells has not been sufficiently tested to support its clinical use for bone augmentation procedures. OBJECTIVE: This study aimed to assess the effects of ST on osteogenic activity and gene expression in SaOS-2 cells. MATERIAL AND METHODS: SaOS-2 deposition of mineralizing matrix in response to increasing doses of ST (0-1000 nM) was evaluated through Alizarin Red S and Calcein Green staining techniques at 6, 12 and 24 days. Gene expression of runt-related transcription factor 2 (RUNX2), vitamin D receptor (VDR), osteopontin (SPP1) and osteonectin (ON) was analyzed by RT-PCR. RESULTS: ST significantly influenced SaOS-2 osteogenic activity: stainings showed the presence of rounded calcified nodules, which increased both in number and in size over time and depending on ST dose. RT-PCR highlighted ST modulation of genes related to osteogenic differentiation. CONCLUSIONS: This study provided encouraging results, showing ST promoted the osteogenic commitment of SaOS-2 cells. Further studies are required to validate these data in primary osteoblasts and to investigate ST molecular pathway of action.

Osteoblasts preferentially adhere to peaks on micro-structured titanium.

The aim of the study was to investigate cell adhesion to micro-structured titanium. Osteoblastic MC3T3 cells were cultured on smooth (P) or sand-blasted/acid-etched (SLA) titanium discs and were observed at scanning electron microscope/focused ion beam (SEM/FIB). Myosin II and actin microfilaments were labelled for epifluorescence microscopy. FIB revealed that cell adhesion initiated centrally and expanded to the cell periphery and that cells attached on the substrate by bridging over the titanium irregularities and adhering mostly on surface peaks. Gaps were visible between concave areas and cytoplasm and areas around ridges represented preferred attachment points for cells. A different myosin distribution was observed between samples and myosin inhibition affected cell responses. Taken together our data indicate that cells attach on micro-rough titanium by bridging over its irregularities. This is likely mediated by myosin II, whose distribution is altered in cells on SLA discs.

"Over-inlay" block graft and differential morphometry: a novel block graft model to study bone regeneration and host-to-graft interfaces in rats.

PURPOSE: The aim of this study was to present new a model that allows the study of the bone healing process, with an emphasis on the biological behavior of different graft-to-host interfaces. A standardized "over-inlay" surgical technique combined with a differential histomorphometric analysis is presented in order to optimize the use of critical-size calvarial defects in pre-clinical testing. METHODS: Critical-size defects were created into the parietal bone of 8 male Wistar rats. Deproteinized bovine bone (DBBM) blocks were inserted into the defects, so that part of the block was included within the calvarial thickness and part exceeded the calvarial height (an "over-inlay" graft). All animals were sacrificed at 1 or 3 months. Histomorphometric and immunohistochemical evaluation was carried out within distinct regions of interest (ROIs): the areas adjacent to the native bone (BA), the periosteal area (PA) and the central area (CA). RESULTS: The animals healed without complications. Differential morphometry allowed the examination of the tissue composition within distinct regions: the BA presented consistent amounts of new bone formation (NB), which increased over time (24.53%±1.26% at 1 month; 37.73%±0.39% at 3 months), thus suggesting that this area makes a substantial contribution toward NB. The PA was mainly composed of fibrous tissue (71.16%±8.06% and 78.30%±2.67%, respectively), while the CA showed high amounts of DBBM at both time points (78.30%±2.67% and 74.68%±1.07%, respectively), demonstrating a slow remodeling process. Blood vessels revealed a progressive migration from the interface with native bone toward the central area of the graft. Osterix-positive cells observed at 1 month within the PA suggested that the periosteum was a source of osteoprogenitor elements. Alkaline phosphatase data on matrix deposition confirmed this observation. CONCLUSIONS: The present model allowed for a standardized investigation of distinct graft-to-host interfaces both at vertically augmented and inlay-augmented sites, thus possibly limiting the number of animals required for pre-clinical investigations.

Comparison of Environmental Scanning Electron Microscopy in Low Vacuum or wet mode for the investigation of cell biomaterial interactions.

AIM: The aim of the present study was to investigate the efficacy of environmental scanning electron microscopy (ESEM), in low vacuum mode (LV-ESEM) and in wet mode (wet-ESEM) in the assessment of cell-material interactions. METHODS: Mouse calvaria MC3T3 cells (ATCC) were seeded on commercially pure machined titanium discs of 10 mm diameter in Dulbecco modified MEM, 10% Fetal Bovine Serum, 1% Penicillin and Streptomycin and 1% Glutamine. Samples were then processed for microscope observation by rinse in Phosphate Buffer saline and fixation in 4.5% Glutaraldehyde. Samples were then rinsed in Sodium Cacodylate buffer and observed or dehydrated in alcohol prior to LV-ESEM observation. Fresh samples in 0.9% NaCl solution were observed in wet- ESEM. RESULTS: No significant loss of detail was observed when dehydrated or non dehydrated samples were analysed at LV-ESEM.The observation of fresh samples in wet-ESEM however proved difficult for the need to eliminate water which forms a layer covering the sample, thus hiding cell surface details. When reducing the vapor pressure in the chamber, the layer evaporated and NaCl immediately started to precipitate and cells collapsed, thus no further investigation was possible. CONCLUSIONS: The use of low vacuum-ESEM after cell fixation, but without dehydration or gold sputter coating proved a viable alternative to traditional high vacuum SEM observation.

Role of prostaglandin E2 in the modulation of Wnt canonical signaling in cells on microstructured titanium surfaces.

BACKGROUND: Rough surface topography enhances the activation of Wnt canonical signaling, a pathway required for osteoblast differentiation. The present study investigated the effects of the modulation of prostaglandin E2 (PGE2) signaling on osteoblastic differentiation on titanium surfaces for endosseous implants with different topographies. METHODS: C2C12 cells were plated on polished or acid-etched/sand-blasted (SLA) titanium discs and stimulated with 1 µM PGE2 or 100 nM cyclooxygenase inhibitor indomethacin. Activation of Wnt canonical signaling was measured with a reporter system. Gene expression was measured in the same cell system by real-time polymerase chain reaction (RT-PCR). Osteoblastic MC3T3 cells were then plated on polished or SLA titanium discs with or without indomethacin, and their proliferation and the expression of osteoblast-specific genes was assessed by RT-PCR. Cell morphology was furthermore studied on SEM, and cell adhesion was assessed by fluorescent labeling of focal adhesion. RESULTS: PGE2 decreased Wnt signaling stimulation in cells growing on polished or SLA surfaces, while indomethacin increased the expression of Wnt target genes in C2C12 and MC3T3 cells, by reporter assay. Moreover, indomethacin increased the expression of early differentiation marker alkaline phosphatase in MC3T3 cells on polished discs and of late marker osteocalcin in cells on SLA titanium. CONCLUSIONS: Prostaglandin signaling affects the activation of Wnt canonical pathway in osteoblastic and mesenchymal cells on microstructured surfaces.

Photogrammetric method to measure the discrepancy between clinical and software-designed positions of implants.

STATEMENT OF PROBLEM: The position of dental implants placed with software-guided systems should be highly accurate in order to ensure safety and a passive fit of the immediate prosthesis. PURPOSE: The purpose of this study was to measure the discrepancy between the clinical and software-planned position of dental implants by applying a photogrammetric method. MATERIAL AND METHODS: Two casts were obtained, 1 from the surgical template and 1 from the actual position of the implants on the alveolar ridge of a patient. Photogrammetry was then applied to precisely locate the position of each implant on the casts. Because this mathematical technique required the identification of image points and of the relative spatial coordinates, 4 marks were drilled on the implant screw. The position of the implants was then identified as the geometric center of the 4 marks, while the orientation of the implant axis was represented by a vector normal to the plane fitting the points. A series of 16 convergent images all around the object was made using a high-resolution digital camera. A mathematical method called "rototranslation" was used to superimpose the cast images for the comparison. RESULTS: The tests performed on the casts resulted in an average precision level of 4 µm for the locations and less than 1 degree for the axis of the implants. A series of empirical and numerical tests were performed to assess the performance of the procedure and of the measurement protocol. CONCLUSIONS: The photogrammetric method is reproducible and can be used to measure the discrepancy between the software-planned and the real position of dental implants. Considering that the average precision level required for an implant-based prosthesis is approximately 50 µm, the error associated with this method can be considered as negligible.