An epidemiological survey of obstructive sleep apnea-hypopnea syndrome among edentulous population based on modified Berlin questionnaire.

PURPOSE: This study aims to investigate the percentage of people in high risk of obstructive sleep apnea-hypopnea syndrome (OSAHS) in edentulous population using the modified Berlin questionnaire (MBQ), to identify sex difference in percentage of edentulous people at high risk of OSAHS, and to analyze the occurrence rate of OSAHS-related symptoms that were not included in the MBQ in this group of people. METHODS: Five hundred and forty patients (edentulous in mandible or maxilla or both) were recruited to participate in this study. Demographic information, nocturnal denture wearing habit, and sleeping posture were recorded. Meanwhile, subjects completed the MBQ in which participants' snoring behavior, wake-time sleepiness or fatigue, and the presence of obesity or hypertension were investigated. RESULTS: Four hundred qualified questionnaires were obtained. According to the MBQ, about 31 % of the subjects were classified at high risk of OSAHS. No significant difference in the percentage of people at high risk of OSAHS was found between male and female groups. Dry or sore mouth and throat, polyuria during sleep, and difficult to fall asleep/easy to wake up showed high occurrence rate equal to or higher than 60 % in the high-risk group. CONCLUSIONS: According to the MBQ, about 31 % of the edentulous population was identified as high risk of OSAHS. Equal attention should be given to elderly edentulous female and male since they are at the same level of risk of developing OSAHS.

Influence of marginal bone resorption on two mini implant-retained mandibular overdenture: An in vitro study.

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 × 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), while there was no statistical difference between the normal and resorption group (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.

Effect of Nerve Growth Factor on Osseointegration of Titanium Implants in Type 2 Diabetic Rats.

PURPOSE: Compared with the general population, a poorer quality of bone-implant osseointegration occurs and at a higher failure rate in patients with type 2 diabetes mellitus. The aim of this study was to analyze the effects of local injection of nerve growth factor at the bone-implant interface after implantation in type 2 diabetic rats. MATERIALS AND METHODS: Goto-Kakizaki (GK) rats (n = 30) were used as a model of type 2 diabetes mellitus, and Wistar rats were used as a control (n = 15). GK rats were assigned randomly into two groups (n = 15/group): the diabetes mellitus group (saline only) and the nerve growth factor group (received nerve growth factor treatment). One titanium implant was placed in each rat's left tibia. Immediately postoperatively, nerve growth factor group rats were injected with nerve growth factor (0.4 µg/day) intramuscularly around the implant, daily for 7 days. Diabetes mellitus and control group rats received normal saline in an identical manner. Rats were sacrificed at 2, 4, and 8 weeks following implant surgery. RESULTS: Traditional light and confocal laser scanning microscopy were used on nondecalcified sections to investigate fluorochrome labeling changes and histologic features of bone adjoining the implants. Bone-to-implant contact and bone volume percentage in the diabetes mellitus group were significantly less than in the control and nerve growth factor groups, with no statistically significant differences between the control and nerve growth factor groups. Confocal laser scanning microscopy showed a significant increase in marked bone around the nerve growth factor group implant at 4 weeks (P < .01) and 8 weeks (P < .05) compared with the diabetes mellitus group. CONCLUSION: This study showed that local injection of nerve growth factor could improve implant-bone osseointegration in diabetic rats and may have important clinical implications.

[Effect of nerve growth factor on the early phase of osseointegration around oral implants].

OBJECTIVE: 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. METHODS: 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. RESULTS: 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)%]. CONCLUSIONS: 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.

In vitro wear resistance of three types of composite resin denture teeth.

STATEMENT OF PROBLEM: The wear resistance of artificial teeth is important to the life of the removable prosthesis for the edentulous patient. The ability of artificial teeth to maintain a stable occlusal relationship over time may be influenced by this property. PURPOSE: The purpose of this in vitro study was to evaluate the wear resistance of artificial teeth based on composite resin filler content when opposed by a denture tooth antagonist. MATERIAL AND METHODS: The right first molars (both maxillary and mandibular) of 3 composite resin denture teeth (Endura, 47% organic filler; Duradent, 42% organic and inorganic filler; and Duracross, 68% organic filler) were secured in an in vitro 2-body wear-testing apparatus that simulated masticatory function (60 strokes/min, grinding distance of 2 mm, under 37 degrees C flowing water). Wear resistance was assessed as volume loss (mm3) and height loss (mm) at 5 kgf (grinding force) after 50,000 strokes (6 pairs for each type). The Vickers microhardness (VHN) of the occlusal surfaces was measured with a load of 50 g and a loading time of 30 seconds. After testing, the worn surfaces were observed with a scanning electron microscope (SEM). Mean values were analyzed using a 1-way analysis of variance followed by the Fisher test (alpha=.05). RESULTS: The volume loss of Duradent teeth (0.87 +/- 0.03 mm3) was significantly higher than of the 2 other types of teeth tested (P<.001). The Duracross teeth (0.22 +/- 0.08 mm3 and 0.11 +/- 0.04 mm) exhibited the best wear resistance of the denture teeth tested. The wear resistance of the materials tested was consistent with their hardness (Endura 27.54 +/- 0.67 VHN, Duradent 24.00 +/- 0.60 VHN, Duracross 39.64 +/- 3.11 VHN). SEM observation showed that many filler particles were missing from the matrix of Duradent. CONCLUSION: The wear resistance among the 3 types of teeth was significantly different; Duracross and Endura were more wear resistant than Duradent. Although the densities as reported by the manufacturer were similar, hardness and microstructure were the primary factors affecting the wear resistance of artificial teeth. Hardness appears to correlate with wear resistance since the wear resistance of Duradent with a lower VHN of 24 was greater than the other 2 types of teeth with greater hardness.

[A pilot study on jaw relation of edentulous patients with digital cephalometric system].

OBJECTIVE: To study the edentulous patients facio-maxillary characters, and discuss the base of recording jaw relation by swallowing action. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.