Sensory innervation around immediately vs. delayed loaded implants: a pilot study

Although neurophysiological and psychophysical proof of osseoperception is accumulating, histomorphometric evidence for the neural mechanisms of functional compensation following immediate and delayed implant loading is still lacking. For this randomized split-mouth study, six mongrel dogs randomly received one of four treatment protocols at 36 implant-recipient sites over 16 weeks （third maxillary incisor, third and fourth mandibular premolar）： immediate implant placement and immediate loading （liP＋ IL）; delayed implant placement and delayed loading （DIP＋DL）; delayed implant placement and immediate loading （DIP＋IL）; and natural extraction socket healing （control）. Histomorphometry was performed in the peri-implant bone and soft tissues within 300 pm around the implants. Immunocytochemistry and transmission electron microscopy were used to confirm the presence of neural structures and to reveal their ultrastructural characteristics, respectively. Myelinated nerve fibres densely populated the peri-implant crestal gingival and apical regions, although they were also identified in the woven bone and in the osteons near the implant threads. Compared with the control group in the mandible, the group that received IIP＋IL showed a higher innervation （in N.mm^-2, 5.94±1.12 vs. 3.15±0.63, P〈0.001） and smaller fibre diameter （in pm, 1.37±0.05 vs. 1.64±0.13, P=0.016）, smaller axon diameter （in pm, 0.89±0.05 vs. 1.24±0,10, P=0.009） and g-ratio （0.64±0.04 vs. 0.76±0.05, P〈0.001） in the middle region around the implants. Compared with DIP＋IL in the mandible, IIP＋IL had a higher nerve density （in N.mm^-2, 13.23±2.54 vs. 9.64±1.86, P=0.027）, greater fibre diameter （in pm, 1.32±0.02 vs. 1.20±0.04, P=0.021）, greater axon diameter （in μm, 0.92±0.01 vs. 0.89±0.03, P=-0.035） and lower g-ratio （0.69±0.01 vs. 0.74±0.01, P=-0.033） in the apical region around the implants. It may be assumed that the treatment protocol with liP＋ IL is the preferred method to allow optimized peri-implant re-innervation, but further functional measurements are still required.

A histological and biomechanical study of bone stress and bone remodeling around immediately loaded implants

Immediate loading(IL)increases the risk of marginal bone loss.The present study investigated the biomechanical response of peri-implant bone in rabbits after IL,aiming at optimizing load management.Ninety-six implants were installed bilaterally into femurs of 48 rabbits.Test implants on the left side created the maximal initial stress of 6.9 and 13.4 MPa in peri-implant bone and unloaded implants on the contralateral side were controls.Bone morphology and bone-implant interface strength were measured with histological examination and push-out testing during a 12-week observation period.Additionally,the animal data were incorporated into finite element(FE)models to calculate the bone stress distribution at different levels of osseointegration.Results showed that the stress was concentrated in the bone margin and the bone stress gradually decreased as osseointegration proceeded.A stress of about 2.0 MPa in peri-implant bone had a positive effect on new bone formation,osseointegration and bone-implant interface strength.Bone loss was observed in some specimens with stress exceeding 4.0 MPa.Data indicate that IL significantly increases bone stress during the early postoperative period,but the load-bearing capacity of peri-implant bone increases rapidly with an increase of bone-implant contact.Favorable bone responses may be continually promoted when the stress in peri-implant bone is maintained at a definite level.Accordingly,the progressive loading mode is recommended for IL implants.

Effects of Immediate Dental Loading Implant Therapy on Electroencephalography (EEG) and Stress

Purpose: Implant therapy restores masticatory function by restoring lost tooth morphology. It has been shown that mastication contributes not only to food intake and digestion, but also to the improvement of overall health. However, there have been no studies on the effects of implant treatment on electroencephalography (EEG). In this study, we investigated the effects of restoration of masticatory function by implant treatment on EEG and stress. Methods: 13 subjects (6 males, 7 females, age 64.1 ± 5.8 years) who had lost masticatory function due to tooth loss and 11 healthy subjects (6 males, 5 females, age 47.6 ± 2.4 years) as a control group. EEG (θ, α, β waves, α/β ratio) and salivary cortisol were measured before immediate dental implant treatment and every month of treatment for 6 months. EEG (θ, α, β waves, α/β ratio) was measured with a simple electroencephalograph miniature DAQ terminal (Intercross-410, Intercross Co., Ltd., Japan) in a resting closed-eye condition, and salivary cortisol was measured using an ELISA kit. Results: Compared to the control group, the appearance of θ and α waves were significantly decreased and β waves were increased, and α/β ratio was significantly decreased. The cortisol level of the subject group was significantly higher compared with the control group. With the course of implant treatment, the appearance of θ and α waves of the subject group increased, while β waves decreased. However, no significant difference was observed. The α/β ratio of the subject group increased from the first month after implant treatment and increased significantly after 5 and 6 months (0 vs. 5 months: p < 0.05, 0 vs. 6 months: p < 0.01). The cortisol levels in the subject group decreased from the first month after implant treatment and significantly decreased after 3 or 4 months (0 vs. 3 months: p < 0.05, 0 vs. 4 months: p < 0.01). These results suggest that tooth loss causes mental stress, which decreases brain stimulation and affects function. Restoration of masticatory function by implants was suggested to alleviate the effects on brain function and stress.

The Behavior of New Hydrophilic Composite Bone Cements for Immediate Loading of Dental Implant

We introduced the hydrophilic groups to acrylic bone cement to improve compliance and achieve more interdigitation between the bone and the acrylic bone cement in order to create better substrates for immediate loading. FTIR-ATR, contact angle, and maximum breach torque were employed for measurement. The results reveal that the introduction of hydrophilic functional groups has increased PMMA＇s surface hydrophilicity after contact angle test. FTIR-ATR results suggest the hydrophilic groups participate in the polymerization reactions, and maximum breach torque of the hydrophilic acrylic bone cements is near 110 Ncm torque. Those effects make it possible for conventional acrylic bone cement application in immediate loading of dental implant.

Simultaneous Upper and Lower Jaw Extractions, Autogenous Bone Augmentation and Temporary Implant Placement with Immediate Loading

Aims: We expanded the known technique for simultaneously augmenting an atrophic maxilla and placement of immediate provisional implants (IPI), followed by immediate loading by performing surgery in both jaws simultaneously. Feasibility of this new technique, implant survival and success were evaluated as well as prosthetic success. Materials and Methods: All patients undergoing simultaneous bone grafting and IPI placement with immediate loading at our institute between the 1st of June 2016 and the 30th of May 2018 were included and followed up for at least one year postoperatively. Results: 3 patients were followed for a mean period of 25.67 months (20 - 29 months). 33 IPIs were placed. All were immobile at second stage surgery without signs of infection. No provisional bridges were lost and no infections were noted. After second stage surgery, none of these 36 final dental implants were lost. There was some bone loss at one implant. In all patients, good functional and aesthetic results were obtained without any unforeseen complications. This renders the implant survival at 100% and the success rate at 97%. Conclusion: The technique is complex due to the intricate step-by-step process that is required and depends on a dedicated team to ensure a proper workflow. When performed correctly, the protocol shows good and predictable results.

Search of Biomarker in the Oral Rehabilitation

Are there any ways to analyze objectively if any good changes happen to the bodies for the patients with acquired edentulous by getting a treatment to recover occlusion? In this study, we focused on interleukin 6 (IL-6) as inflammatory cytokine, cortisol known as a stress related substance and secretory immune globulin A (SIgA) related to immune reaction, and chose 14 patients who had occlusion reconstructed by the immediately loaded dental implants because occlusion contact with maxillary and mandibular dentition was lost caused by edentulous jaws or maxillary and mandibular teeth crossing each other and their jaw position and central occlusion position could not settle, and verified the relationship with changes of patients’ physical and mental states during the 6 months of the treatment and the effect of the immediately loaded implants treatment by using saliva which was non-invasive and easy to sample in biomarkers in saliva. Moreover for female subjects, the changes of facial color tones were measured by using Robo Skin Analyz-er?, a digital image analyzer, to measure the condition of their skin. In conclusion, the positive correlation between the amount of IL-6 and cortisol was not admitted. However, it was admitted that IL-6 tended to increase when a systemic change which interrupted curing such as the interruption of fusion of the implant and the bone was observed even though the patient did not notice any particular symptoms and cortisol tended to increase when the patient noticed discomfort and mentioned any events under stress on his or her medical record. Moreover with the skin color analysis by Robo Skin Analyzer?, the possibility that the occlusion treatment by the immediate implant had an effect on physical and psychological health promotion through the acquisition of the masticatory function and the aesthetic recovery was indicated.