189 research outputs found
Implant primary stability and occlusion
No full textIn this chapter, we have focused on the primary implant stability not only from a biomechanical bone-implant perspective but also taking into account the neuromotor functions that could generate occlusal dynamic, asymmetric, and extra-axial loads.From the biomechanical bone-implant perspective, a microcomputed tomography image-based approach combined with the finite element method has been used to investigate the effect of the drill size on the biomechanics stability of the dental implant technique.In the case of neuromotor functions, to achieve a complete clinical evaluation of mastication, an in-depth neurophysiopathological assessment of masticatory muscle control has been described through the trigeminal electrophysiological approach.In conclusion, the implant-prosthetic primary stability is a biomechanical result in a "complex system" in which the direct components can coexist, such as the bone-implant relationship (press-fit phenomenon), and indirect components such as the occlusal loads are determined by the neuromuscular forces where the symmetry and synchronicity of the occlusal contacts are determined
Trigeminal electrophysiology: a 2 x 2 matrix model for differential diagnosis between temporomandibular disorders and orofacial pain.
No full textBackground
Pain due to temporomandibular disorders (TMDs) often has the same clinical symptoms and signs as other types of orofacial pain (OP). The possible presence of serious neurological and/or systemic organic pathologies makes differential diagnosis difficult, especially in early disease stages. In the present study, we performed a qualitative and quantitative electrophysiological evaluation of the neuromuscular responses of the trigeminal nervous system. Using the jaw jerk reflex (JJ) and the motor evoked potentials of the trigeminal roots (bR-MEPs) tests, we investigated the functional and organic responses of healthy subjects (control group) and patients with TMD symptoms (TMD group).
Method
Thirty-three patients with temporomandibular disorder (TMD) symptoms and 36 control subjects underwent two electromyographic (EMG) tests: the jaw jerk reflex test and the motor evoked potentials of the trigeminal roots test using bilateral electrical transcranial stimulation. The mean, standard deviation, median, minimum, and maximum values were computed for the EMG absolute values. The ratio between the EMG values obtained on each side was always computed with the reference side as the numerator. For the TMD group, this side was identified as the painful side (pain side), while for the control group this was taken as the non-preferred masticatory side (non-preferred side). The 5th, 10th, 25th, 50th, 75th, 90th, and 95th percentiles were also calculated.
Results
Analysis of the ratios (expressed as percentages) between the values obtained on both sides revealed a high degree of symmetry in the bR-MEPs % in the control (0.93 ± 0.12%) and TMD (0.91 ± 0.22%) groups. This symmetry indicated organic integrity of the trigeminal root motor fibers and correct electrode arrangement.
A degree of asymmetry of the jaw jerk's amplitude between sides (ipJJ%), when the mandible was kept in the intercuspal position, was found in the TMD group (0.24% ± 0.14%) with a statistically significant difference in relation to the control group (0.61% ± 0.2%). This asymmetry seemed to be primarily due to a failure to facilitate the reflex on the painful side in intercuspal position.
Conclusions
In this 2 × 2 matrix diagnostic model, three different types of headache may be identified: 1) those due to organic pathologies directly and indirectly involving the trigeminal nervous system denoted as "Organic Damage"; 2) those in TMD patients; 3) other types of orofacial pain in subjects who could erroneously be considered healthy, denoted as Orofacial Pain "OP". This category of patient should be considered at risk, as organic neurological pathologies could be present and yet not directly affect the trigeminal system, at least in the early stages of the disease
Integration of 3D anatomical data obtained by CT imaging and 3D optical scanning for computer aided implant surgery
No full textAbstract Background A precise placement of dental implants is a crucial step to optimize both prosthetic aspects and functional constraints. In this context, the use of virtual guiding systems has been recognized as a fundamental tool to control the ideal implant position. In particular, complex periodontal surgeries can be performed using preoperative planning based on CT data. The critical point of the procedure relies on the lack of accuracy in transferring CT planning information to surgical field through custom-made stereo-lithographic surgical guides. Methods In this work, a novel methodology is proposed for monitoring loss of accuracy in transferring CT dental information into periodontal surgical field. The methodology is based on integrating 3D data of anatomical (impression and cast) and preoperative (radiographic template) models, obtained by both CT and optical scanning processes. Results A clinical case, relative to a fully edentulous jaw patient, has been used as test case to assess the accuracy of the various steps concurring in manufacturing surgical guides. In particular, a surgical guide has been designed to place implants in the bone structure of the patient. The analysis of the results has allowed the clinician to monitor all the errors, which have been occurring step by step manufacturing the physical templates. Conclusions The use of an optical scanner, which has a higher resolution and accuracy than CT scanning, has demonstrated to be a valid support to control the precision of the various physical models adopted and to point out possible error sources. A case study regarding a fully edentulous patient has confirmed the feasibility of the proposed methodology.</p
Integration of 3D anatomical data obtained by CT imaging and 3D optical scanning for computer aided implant surgery.
No full textBiomechanics of the press-fit phenomenon in dental implantology: an image-based finite element analysis
No full textAbstract Background A fundamental pre-requisite for the clinical success in dental implant surgery is the fast and stable implant osseointegration. The press-fit phenomenon occurring at implant insertion induces biomechanical effects in the bone tissues, which ensure implant primary stability. In the field of dental surgery, the understanding of the key factors governing the osseointegration process still remains of utmost importance. A thorough analysis of the biomechanics of dental implantology requires a detailed knowledge of bone mechanical properties as well as an accurate definition of the jaw bone geometry. Methods In this work, a CT image-based approach, combined with the Finite Element Method (FEM), has been used to investigate the effect of the drill size on the biomechanics of the dental implant technique. A very accurate model of the human mandible bone segment has been created by processing high resolution micro-CT image data. The press-fit phenomenon has been simulated by FE analyses for different common drill diameters (DA = 2.8 mm, DB = 3.3 mm, and DC = 3.8 mm) with depth L = 12 mm. A virtual implant model has been assumed with a cylindrical geometry having height L = 11 mm and diameter D = 4 mm. Results The maximum stresses calculated for drill diameters DA, DB and DC have been 12.31 GPa, 7.74 GPa and 4.52 GPa, respectively. High strain values have been measured in the cortical area for the models of diameters DA and DB, while a uniform distribution has been observed for the model of diameter DC . The maximum logarithmic strains, calculated in nonlinear analyses, have been ϵ = 2.46, 0.51 and 0.49 for the three models, respectively. Conclusions This study introduces a very powerful, accurate and non-destructive methodology for investigating the effect of the drill size on the biomechanics of the dental implant technique. Further studies could aim at understanding how different drill shapes can determine the optimal press-fit condition with an equally distributed preload on both the cortical and trabecular structure around the implant.</p
Biomechanics of the press-fit phenomenon in dental implantology: an image-based finite element analysis.
No full textBackground: A fundamental pre-requisite for the clinical success in dental implant surgery is the fast and stable implant osseointegration. The press-fit phenomenon occurring at implant insertion induces biomechanical effects in the bone tissues, which ensure implant primary stability. In the field of dental surgery, the understanding of the key factors governing the osseointegration process still remains of utmost importance. A thorough analysis of the biomechanics of dental implantology requires a detailed knowledge of bone mechanical properties as well as an accurate definition of the jaw bone geometry.
Methods: In this work, a CT image-based approach, combined with the Finite Element Method (FEM), has been used to investigate the effect of the drill size on the biomechanics of the dental implant technique. A very accurate model of the human mandible bone segment has been created by processing high resolution micro-CT image data. The press-fit phenomenon has been simulated by FE analyses for different common drill diameters (D-A = 2.8 mm, D-B = 3.3 mm, and D-C = 3.8 mm) with depth L = 12 mm. A virtual implant model has been assumed with a cylindrical geometry having height L = 11 mm and diameter D = 4 mm.
Results: The maximum stresses calculated for drill diameters D-A, D-B and D-C have been 12.31 GPa, 7.74 GPa and 4.52 GPa, respectively. High strain values have been measured in the cortical area for the models of diameters D-A and D-B, while a uniform distribution has been observed for the model of diameter D-C. The maximum logarithmic strains, calculated in nonlinear analyses, have been E = 2.46, 0.51 and 0.49 for the three models, respectively.
Conclusions: This study introduces a very powerful, accurate and non-destructive methodology for investigating the effect of the drill size on the biomechanics of the dental implant technique.
Further studies could aim at understanding how different drill shapes can determine the optimal press-fit condition with an equally distributed preload on both the cortical and trabecular structure around the implant
Correction: Might Fibroblasts from Patients with Alzheimer’s Disease Reflect the Brain Pathology? A Focus on the Increased Phosphorylation of Amyloid Precursor Protein Tyr682 Residue, (Brain Sci, (2021), 11, 103, 10.3390/brainsci1101010)
No full textIn the original article [1], there was a mistake in “Figure 3”. During the assembly of Figure 3, Western blot panels labeled with APPpTyr, APP, and β-actin were mistakenly used for familiar patients with AD, AD, and healthy controls. This error also affected the optical density analysis of the APPpTyr levels reported in Figure 1 and Figure 3B, where the values corresponding to Figure 3 needed to be replaced. In contrast, APP and β-actins optical density analyses were performed on the correct panels that are now reported in Figure 3 and did not require changes in the corresponding Figure 3C–E. Nonetheless, these errors did not influence the overall significance of the results, which remain consistent with those reported and discussed in this article. The corrected “Figure 1 and Figure 3” appear below. The authors apologize for any inconvenience caused and state that the scientific conclusions are unaffected. The original article has been updated
Plasma levels of n-3 polyunsaturated fatty acids and cognitive decline: possible role of depressive symptoms and apolipoprotein E genotyping
No full textThe reability of the bilateral trigeminal roots-motor evoked potentials as an organic normalization factor: symmetry or not symmetry?
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