ABSTRACT
PURPOSE@#To investigate the biomechanical effect of marginal bone resorption (MBR) on the mandibular mini implant (MI)-retained overdenture (MI-OD) on the edentulous model. @*MATERIALS AND METHODS@# The experimental mandibular edentulous model was modified from a commercial model with 2 mm thick artificial soft tissue under denture base. Two MIs (Φ2.6 mm x 10 mm) were bilaterally placed between the lateral incisor and the canine area and attached with magnetic attachments. Three groups were set up as follows: 1) alveolar bone around the MI without MBR (normal group), 2) with MBR to 1/2 the length of the implant (resorption group), and 3) complete denture (CD) without MI (CD group). Strain around the MI, pressure near the first molar area, and displacement of denture were simultaneously measured, loading up to 50 N under bilateral/ unilateral loading. Statistical analysis was performed using independent-samples t test and one-way ANOVA (α=.05). @*RESULTS@#The strain around the MI with MBR was approximately 1.5 times higher than that without MBR. The pressure in CD was higher than in MI-ODs (P .05). Similarly, the CD demonstrated a greater displacement of the denture base than did the MI-ODs during bilateral and unilateral loadings (P <.05). @*CONCLUSION@#The strain around the MI with MBR was approximately 1.5 times higher than that without MBR. The pressure on posterior alveolar ridge and denture displacement of MI-ODs significantly decreased compared to CDs, even when MBR occurs. Bilateral balanced occlusion was recommended for MI-ODs, especially when MBR occurred.
ABSTRACT
<p><b>OBJECTIVE</b>To observe the early bone integration of oral implants after injection of exogenous nerve growth factor (NGF) and investigate the effects of NGF on peri-implant osseointegration.</p><p><b>METHODS</b>Twelve New Zealand white rabbits were used in this study to establish bi-mandible implant model. Then local injection of 1 µg NGF was given on the right side of the mandible as experimental group and normal saline only was injected on the left side as control group once a day for seven days. The rabbits were respectively sacrificed at 2, 4 and 8 weeks after surgery. The implant-bone grinding samples were prepared and stained by toluidine blue for general observation, X-ray, histology and bone histomorphometry analysis.</p><p><b>RESULTS</b>The density of the new bone around implants at 2 and 4 weeks was lower than normal bone. Compared with the control group, the quantity of new bone and bone-implant contact ratio significantly increased in the experimental group. At 8 weeks, the new bone density in both groups was similar to the normal bone. In the experimental group, the haversian system was observed. Bone contact ratio was significantly different between experimental and control group at 2 and 4 weeks, but similar at 8 weeks.[control group at 2 weeks (26.67 ± 3.88)%, 4 weeks (52.59 ± 5.07)% and 8 weeks (97.33 ± 6.75)%, experimental group at 2 weeks (42.24 ± 6.67)%, 4 weeks (72.25 ± 6.30)% and 8 weeks (99.15 ± 4.68)%].</p><p><b>CONCLUSIONS</b>Applying exogenous NGF in the early phase could accelerate the formation and maturation of trabecular bone around the implants and shorten the period of osseointegration. Nerve growth factor could promote osseointegration in the early stage of oral implantation.</p>
Subject(s)
Animals , Rabbits , Bone Density , Bone and Bones , Dental Implants , Mandible , Nerve Growth Factor , Pharmacology , Osseointegration , Prostheses and ImplantsABSTRACT
<p><b>OBJECTIVE</b>To study the edentulous patients facio-maxillary characters, and discuss the base of recording jaw relation by swallowing action.</p><p><b>METHODS</b>Forty-three edentulous patients were included in this study, age ranged from 57 to 70 yr, with new comfortable full dentures. Two lateral cephalograms for one patient were taken by SIRONA digital X-ray dental system, one of which was centric occlusion with full denture, another was the end position of swallowing action without denture.</p><p><b>RESULTS</b>The vertical facial dimensions of male were a little more than that of female. The ratio of lower front facial height/upper front facial height was about 6/5, angle S-N-Po was about 78 approximately 80 degrees. These data may be useful for dentists to make diagnoses if the jaw relation is right or not. Both in vertical or anterior-posterior (horizontal) dimension, the differences between two groups (two actions in one patient) were not significant. It showed that two positions of two actions were the same.</p><p><b>CONCLUSIONS</b>The SIRONA digital X-ray dental system for cephalometry was swift, and had its own characters. The way of swallowing and occluding is one of efficient methods to record the jaw relation of edentulous patients veraciously and naturally.</p>