Effects of Low-Intensity Pulsed Ultrasound on Implant Osseointegration in Ovariectomized Rats.

OBJECTIVES: To investigate the effect of low-intensity pulsed ultrasound (US) on periimplant bone healing and osseointegration under osteoporotic conditions. METHODS: Seventy-two 12-week-old female Sprague Dawley rats received bilateral ovariectomies. Twelve weeks later, titanium implants were bilaterally placed in the proximal tibial metaphysis. The right tibia was exposed to low-intensity pulsed US (40 mW/cm2, spatial and temporal average) for 20 min/d starting the 2nd day after implantation, and the left tibia served as a control without stimulation. The rats were randomly assigned to 6 groups of 12 each according to the US duration (group 1: weeks 0­2, 280 minutes; group 2: weeks 0­4, 560 minutes; group 3: weeks 0­6, 840 minutes; group 4: weeks 0­8, 1120 minutes; group 5: weeks 0­10, 1400 minutes; group 6: weeks 0­12, 1680 minutes). At the end of the 2nd, 4th, 6th, 8th, 10th, and 12th weeks, the rats were euthanized, and bilateral tibias were harvested. Peri-implant bone volume and bone-implant contact were assessed by micro­computed tomography; the implantbone interface was assessed histologically; and implant fixation strength was determined by a removal torque test. RESULTS: Low-intensity pulsed US increased bone-implant contact at the 4th, 6th, 8th, 10th, and 12th weeks (P = .019, .017, <.001, <.001, and <.001, respectively) and periimplant bone volume at all times (P = <.001, .002, .012, .007, .005, and .010). Removal torque on the US side was improved at the 6th, 8th, 10th, and 12th weeks (P= .012, <.001, .006, and .009). Ultrasound evoked a favorable bone response in the histologic study. CONCLUSIONS: Low-intensity pulsed US might enhance new bone formation, especially at an early stage, and improve osseointegration in osteoporotic bone as an auxiliary method. However, further studies are needed to elucidate the mechanisms underlying its action.

Effects of Low-Intensity Pulsed Ultrasound on Implant Osseointegration in Ovariectomized Rats.

OBJECTIVES: To investigate the effect of low-intensity pulsed ultrasound (US) on peri-implant bone healing and osseointegration under osteoporotic conditions. METHODS: Seventy-two 12-week-old female Sprague Dawley rats received bilateral ovariectomies. Twelve weeks later, titanium implants were bilaterally placed in the proximal tibial metaphysis. The right tibia was exposed to low-intensity pulsed US (40 mW/cm2 , spatial and temporal average) for 20 min/d starting the 2nd day after implantation, and the left tibia served as a control without stimulation. The rats were randomly assigned to 6 groups of 12 each according to the US duration (group 1: weeks 0-2, 280 minutes; group 2: weeks 0-4, 560 minutes; group 3: weeks 0-6, 840 minutes; group 4: weeks 0-8, 1120 minutes; group 5: weeks 0-10, 1400 minutes; group 6: weeks 0-12, 1680 minutes). At the end of the 2nd, 4th, 6th, 8th, 10th, and 12th weeks, the rats were euthanized, and bilateral tibias were harvested. Peri-implant bone volume and bone-implant contact were assessed by micro-computed tomography; the implant-bone interface was assessed histologically; and implant fixation strength was determined by a removal torque test. RESULTS: Low-intensity pulsed US increased bone-implant contact at the 4th, 6th, 8th, 10th, and 12th weeks (P = .019, .017, <.001, <.001, and <.001, respectively) and peri-implant bone volume at all times (P = <.001, .002, .012, .007, .005, and .010). Removal torque on the US side was improved at the 6th, 8th, 10th, and 12th weeks (P= .012, <.001, .006, and .009). Ultrasound evoked a favorable bone response in the histologic study. CONCLUSIONS: Low-intensity pulsed US might enhance new bone formation, especially at an early stage, and improve osseointegration in osteoporotic bone as an auxiliary method. However, further studies are needed to elucidate the mechanisms underlying its action.

[Effect of full crown preparation with ultrasound instrument on marginal adaption: a randomized controlled trial].

PURPOSE: To study the effect of full crown ultrasound preparation on crown margin. METHODS: Thirty-two patients with 35 units of full crown were randomly divided into 2 groups. Teeth in the experimental group were prepared with ultrasound diamond instrument while teeth in the control group were prepared with a high-speed hand piece with regular diamond burs. Teeth in both groups were restored using Zirconia full ceramic crowns. Then all patients were evaluated for morphology of finishing line, marginal adaptation and marginal gingival coloration in the proximal side after 6-month of follow-up, respectively. SPSS17.0 software package was used for statistical analysis. RESULTS: Marginal adaptation did not show significant difference between the experimental and control group (P>0.05). Morphology of finishing line and marginal gingival coloration in the proximal side showed significant difference (P<0.05). CONCLUSIONS: It is recommended to perform tooth preparations with ultrasound diamond instruments, which may produce significantly less marginal gingival coloration in the proximal margin after 6-month of follow-up.

[A prospective study of changes in oral health-related quality of life during "all-on-four" immediate restoration for edentulous individuals].

PURPOSE: This clinical study was to evaluate oral health-related quality of life (OHRQoL) changes in patients who underwent all-on-4 treatment in one or both jaws. METHODS: Eleven patients underwent placement of 4 to 6 dental implants on the basis of all-on-4 treatment concept in the maxilla, mandible or both jaws and immediate loading with acrylic interim prostheses. The prostheses were replaced after 3-6 months, and definitive prostheses with metal framework and reinforced resin facing were fixed after another 3 months or more. The subjects completed the shortened Chinese version of the Oral Health Impact Profile (OHIP-14) before surgery (T0), 1 week after interim prostheses were placed (T1) and 3 months after definitive prosthesis placement (T2). The data of 11 subjects were analyzed with Wilcoxon signed-rank test using SPSS 13.0 software package. RESULTS: The total OHIP-14 score significantly reduced only at T2 (P<0.05). "Functional limitation," "physical pain," "physical disability," and "psychological disability" scores significantly decreased at T2, and "psychological discomfort" scores also significantly dropped at T1. "Social disability" and "handicap" scores remained unchanged throughout the treatment course. CONCLUSIONS: Fixed definitive prostheses with metal framework are more effective in improving OHRQoL than fixed acrylic prostheses during all-on-4 treatments.

[Analysis of retention of 3 different aesthetic Co-Cr-Mo alloy clasps on premolars].

PURPOSE: To evaluate the 3-D surface topography of ultrasonically prepared tooth. METHODS: Ten extracted human maxillary premolars were prepared for crowns. A split-tooth model was used to refine the margins: half of the margin was finished with traditional rotary instruments, the other with ultrasonic instruments. The 3-D profiles of the prepared surface were observed under scanning electron microscopy and Talysurf CCI 3000 non-contact 3D profiler, and a quantitative comparison of 3-D surface roughness average(SA) and the surface of skewness(SSK) was conducted with Talymap Gold software. The data were analyzed by independent sample t test using SPSS13.0 software package. RESULTS: The surface finished with ultrasonic instruments exhibited a smoother surface. 3-D surface roughness analysis showed that the SA and SSK of surfaces made by ultrasonic instruments were significantly lower, compared with surfaces produced using conventional rotary instruments. CONCLUSIONS: The ultrasonic instruments produce surface in better condition than the conventional rotary instruments.

Effect of a differently tilted angle of mandibular premolar on fracture resistance of 3 postcore restorations.

OBJECTIVE: The objective of this study was to evaluate the effect of differently tilted mandibular premolars on fracture resistance of 3 postcore restorations. METHODS: Seventy-five extracted human mandibular premolars were simulated to 5 different tilted angles: lingually tilted (LT) 30° and 15°, 0°, and buccally tilted (BT) 15° and 30°, and restored with custom-made metal postcore (CMPC), prefabricated fiber postcore (PFPC), or custom-made fiber postcore (CFPC). Then, a 30° oblique load was applied with a crosshead speed of 1 mm/min to the restoration. Failure loads and fracture modes were analyzed (2-way ANOVA and Tukey test, P < .05). RESULTS: The buccally inclined restoration had higher fracture resistance than that of the lingually tilted restoration. The strength of the PFPC restoration was comparable with that of the CMPC restoration in all tilted groups. As for fracture modes, no significant differences were found among the various tilted restorations. CONCLUSIONS: Buccally tilted mandibular premolars are more likely to be restored with prefabricated fiber postcore than a lingually inclined mandibular premolar.

[The acceleration of titanium implant osseointegration by low intensity pulsed ultrasound: an experimental study in rats].

OBJECTIVE: To establish an animal model of titanium implant and to investigate the effects of low intensity pulsed ultrasound (LIPUS) on the implant osseointegration. METHODS: Twenty-four female Sprague Dawley (SD) rats were used. Titanium implants were inserted into tibia metaphysis bilaterally in each SD rat. Since the second day following implant surgery, LIPUS stimulation were carried out around the implant on the right side for 20 minutes per day, and implants on the left side remain untouched as self-control. Eight rats were sacrificed and tibiae specimens were harvested on the end of the 4th, 8th, and 12th week respectively. X-ray picture, micro-CT analysis and histological sections were performed to evaluate the effects of LIPUS on the implant osseointegration. RESULTS: Osseointegration at the interface between the implant and bone tissue was observed bilaterally. In the micro-CT histomorphometry analysis, the percentage of osseointegration (%OI) of experiment side were (45.708 ± 3.316)%, (46.231 ± 1.954)%, and (46.807 ± 1.451)% on the end of the 4th, 8th, and 12th week. Meanwhile, the %OI of control side were (43.021 ± 3.558)%, (44.272 ± 3.023)%, and (44.894 ± 4.215)% respectively. The %OI on the 4th weekend, bone volume ratio (BV/TV) on the 4th and 8th weekend, trabecular thickness (Tb. Th) and degree of anisotropy (DA) on the 8th and 12th weekend of the experiment side tibia were significantly greater than those on the control side (P < 0.05). The histological examination showed that the thickness of new bone around the implant and the bone-implant contact area was obviously greater in the LIPUS treated side compared to the control side. CONCLUSIONS: The LIPUS therapy may accelerate the bone healing and osseointegration at the interface between titanium implant and bone, and promote remodeling of bone trabecula on the early stage.

Analysis of the effect of CPP-ACP tooth mousse on enamel remineralization by circularly polarized images.

OBJECTIVE: To evaluate the effect of casein phosphopeptide-amorphous calcium phosphate tooth mousse on the remineralization of bovine incisor by circularly polarized images. METHODS: Eighty bovine incisors, each with a 4 x 4 mm artificially demineralized area, were used. The samples were divided into four groups: Group A, casein phosphopeptide-amorphous calcium phosphate tooth mousse; Group B, fluoride toothpaste; Group C, casein phosphopeptide-amorphous calcium phosphate tooth mousse and fluoride toothpaste; and Group D, no treatment. Circularly polarized images were taken after the specimens were treated for 3, 6, 9, or 12 weeks, and the size of the demineralized area and the mean grey level were measured. Data analysis was done using repeated measures variance analysis. Pearson correlation coefficients were computed to evaluate the correlation between the size of the demineralized area and the mean grey level. RESULTS: In all four groups, the size of the demineralized area and the mean grey level declined with time. The size of the demineralized area of Group C was significantly smaller than that of Group A at the end of the third and sixth weeks (P = .039, P = .000, respectively), and the mean grey level of Group C was lower than that of Group A at the end of the 6th and 12th weeks (P = .037, P = .004, respectively). At the end of the 6th, 9th, and 12th weeks, the size of the demineralized area of Group C was smaller (P = .000, P = .005, P = .005, respectively) and the mean grey level was lower (P = .000) than those of Group B. No statistically significant correlations were detected between the size of the demineralized area and the mean grey level. CONCLUSION: Casein phosphopeptide-amorphous calcium phosphate tooth mousse can reduce the size and mean grey level of demineralized areas and promote the remineralization of bovine enamel. Combined application with fluoride toothpaste strengthens the effect.

[Fracture resistance and failure modes of endodontically treated human teeth restored with four different post-core systems].

OBJECTIVE: To compare the fracture resistance and failure modes of endodontically treated human upper premolars restored with different post-core systems. METHODS: 32 extracted human upper premolars were endodontically treated and crowns were sectioned at 2 mm above the labial cement enamel junction (CEJ). The teeth were randomly and equally divided into 4 groups: Group A, teeth restored with cast metal post and metal crown; group B, Tenax Fiber White fiber post and metal crown; group C, EverStick fiber post 1.5 mm in diameter and metal crown; group D, EverStick fiber post 1.5 mm in diameter and add another 1.2 mm diameter EverStick fiber post and metal crown. All the teeth were embedded in acrylic resin blocks, and were subjected to a compressive load at 1 mm/min crosshead speed which delivered at a 45 degrees to the long axis until the first sign of failure was noted. The fracture load and the mode of fracture were recorded. RESULTS: Fracture resistances of the four groups of restored teeth were not significantly different (P>0.05). However, fracture modes in fiber post groups were nearer to CEJ than cast metal post group. CONCLUSION: Fracture resistance of endodontically treated teeth restored with EverStick fiber post is enhanced that it can meet the clinical need, although the flexural resistance of EverStick fiber post itself is the weakest. Fracture modes of all fiber post groups are more favorable than cast metal post group.