Objective: The influences of abutments made from zirconia (Y-TZP) and cement materials on the strength of titanium implants were investigated by using the finite element method.
Methods: Non-linear analysis was performed using a finite element method program (ANSYS Ver. 11, ANSYS, Canonsburg, U. S. A.) and a personal computer. For the analysis model, the bisection, trisection, and modified trisection types, for which the reliability of analytical accuracy has been established by experiments, were used. Regarding the combination of constituent materials, fixtures made of JIS class-4 pure titanium were used for all samples, and the materials of the abutment and abutment-screw were changed. Temporary cement and resin cement were used for adhesion materials. The materials of the superstructure and abutment were the same, and compact bone was used under all conditions. A force of up to 1,000 N was loaded in the 45° oblique direction to the superstructure. The fixture, abutment, and abutment-screw were placed in contact, the bone bottom was entirely fixed, and the lateral sides were fixed excluding the longitudinal direction.
Results: When JIS class-4 pure titanium abutment-screws were used in the trisection type implant, the strength reached the maximum. In the case of the bisection and modified trisection types implants, the strength decreased greatly when using abutments made from zirconia, although their fracture strengths were equivalent to the fatigue strength of JIS class-4 pure titanium implants. The influence of the two types of cement on strength of implant depended on the structure and materials of the implant. However, no major difference due to the cement type was noted in the strength of any implant. Conclusion: When the abutment and superstructure are prepared with zirconia, the maximum strength can be obtained by using JIS class-4 pure titanium abutment-screws in the trisection type. The design appropriate for all titanium implants is not necessarily appropriate for zirconia abutments; an appropriate design for zirconia abutments needs to be investigated. For the two kinds of cement examined, the strength of implant was hardly affected by the kind of cement.
Although dental implant placement is considered to be a safe surgical procedure, this report focuses on two cases with severe hemorrhage during implant placement in the mandible. Excessive hematoma formation in the mouth floor resulted from arterial or venous trauma that occurred during implant socket preparation. The first case was a 60-year-old man who suffered hemorrhage and the formation of a large hematoma in the mouth floor that occurred during insertion socket preparation in the lateral incisor position on the right side of the mandible. The second case was a 57-year-old woman in whom a large hematoma formed in the mouth floor 4 hours after implant placement in the first molar site on the right side of the mandible.
In the first case, the dentist did not consider that the lingual cortex had been perforated. Therefore, we suspected that a small branch of the sublingual artery had been injured in the mandible with a twist drill, and that the vessel had withdrawn into the mouth floor. In the second case, the dentist involved identified a perforation of the lingual cortex, although bleeding had been noticed during the surgery and hemostasis had been achieved at that time. Swelling occurred 4 hours after surgery, although it progressed relatively slowly. Therefore, we suspected that a small vein in the mouth floor had been injured. Severe airway obstruction did not occur in either case.
Though dental implant treatment is mainly intended for functional improvement of disorders in the stomatognathic system resulting from missing teeth, it sometimes leads to unpredictable neurological symptoms in patients. We report two cases of atypical orofacial pain following dental implant placement. The patients were two women aged 50 and 65 years old. Neither patient had established a rapport with the dentist who performed the dental implantation for them. The patients were treated by administration of paroxetine hydrochloride hydrate and milnacipran hydrochloride, in consultation with the physician. We must be conscious of the onset of orofacial pain in dental implant treatment.
The objective of this study was to identify clinical indices for the safe and appropriate determination of insertion sites in mandibular molar implant treatment. The subjects were 286 patients (153 men, 133 women; age 26-78 years) who underwent cone-beam CT scanning prior to implant surgery. The patients were immobilized at the forehead and external auditory meatus in the upright position, and the cone-beam CT image was screened in the occlusal plane horizontally in the state of centric occlusion.
The angle of inclination of the mandible and vertical bone diameter on the lingual side, which are anatomical factors that affect implant insertion planning, were measured on the cone-beam CT images.
As a result, the angle of inclination of the mandible increased from the mesial to the distal side which was consistent with previous reports.
The angle of inclination of the mandible was ≧30º in the second molar in 26.0% of patients. Vertical bone diameter on the lingual side was ≦12 mm in the first molar in 43.78% of patients and ≦12 mm in the second molar in 62.66% of patients, and a high proportion of mandibles posed problems for implant planning.
The morphology of the lingual side of the mandible is difficult to diagnose from panoramic X-ray images. We must perform accurate preoperative diagnosis, including CT scanning, and carry out implant treatment with a high degree of predictability, with safety as the basic premise.
Background: Although it is important to elucidate the deformation distribution of alveolar bone around a dental implant, there are some disadvantages in the existing experimental methods such as strain gauge method, photoelasticity method, etc. Therefore, an advanced experimental technique is required not only for problems but also for showing the validity of numerical analysis such as finite element analysis.
Objective: A new advanced experimental technique combining a bone model and digital image correlation (DIC) method is proposed to enable systematic, quantitative evaluations.
Method: A laminated test block (SAWBONES, WA, USA) having the same bilayer structure as actual bone was employed as the bone model specimen. The DIC method was used to visualize the displacement and strain distributions of alveolar bone around a dental implant.
Results: The new proposed experimental technique made it possible to analyze the deformation distribution around a dental implant systematically and quantitatively.
Conclusions: The proposed experimental technique can be used to assess the deformation distribution behavior of alveolar bone around a dental implant systematically and quantitatively.