Simulation of Low-Intensity Ultrasound Propagating in a Beagle Dog Dentoalveolar Structure to Investigate the Relations between Ultrasonic Parameters and Cementum Regeneration.

The therapeutic effect of low-intensity pulsed ultrasound on orthodontically induced inflammatory root resorption is believed to be brought about through mechanical signals induced by the low-intensity pulsed ultrasound. However, the stimulatory mechanism triggering dental cell response has not been clearly identified yet. The aim of this study was to evaluate possible relations between the amounts of new cementum regeneration and ultrasonic parameters such as pressure amplitude and time-averaged energy density. We used the finite-element method to simulate the previously published experiment on ultrasonic wave propagation in the dentoalveolar structure of beagle dogs. Qualitative relations between the thickness of the regenerated cementum in the experiment and the ultrasonic parameters were observed. Our results indicated that the areas of the root surface with greater ultrasonic pressure were associated with larger amounts of cementum regeneration. However, the establishment of reliable quantitative correlations between ultrasound parameters and cementum regeneration requires more experimental data and simulations.

Effect of low-intensity pulsed ultrasound on orthodontically induced root resorption in beagle dogs.

We investigated the effect of low-intensity pulsed ultrasound (LIPUS) on orthodontically induced inflammatory root resorption in vivo. Ten beagle dogs were treated with an orthodontic appliance to move the mandibular fourth premolars bodily. The orthodontic movement was carried out for 4 wk with a continuous force of 1 N/side; using a split-mouth model, LIPUS was applied daily for 20 min. Fourth premolar and surrounding periodontal tissue were evaluated with micro-computed tomography and hematoxylin and eosin and tartrate-resistant acid phosphatase staining. We calculated the number, volume and distribution of root resorption lacunae and their percentage relative to total root volume, orthodontic tooth movement and periodontal ligament space. There was no significant difference in orthodontic tooth movement between the two sides. LIPUS significantly reduced the number of orthodontically induced inflammatory root resorption initiation areas by 71%, reduced their total volume by 68% and reduced their volume relative to the affected root total volume by 70%. LIPUS induced the formation of a precementum layer, thicker cementum and reparative cellular cementum.

Short-term effect of low-intensity pulsed ultrasound on an ex-vivo 3-d tooth culture.

We investigated the short-term effect of LIPUS on human dentin-pulp complex in vitro. We collected sixty-three premolars from patients who needed the extraction. The premolars were sectioned transversely into 600-µm-thick slices, and then divided into five groups according to LIPUS application time (control, 5, 10, 15 and 20 min). LIPUS transducer produced an incident intensity of 30 mW/cm(2). After 24 h, tissue was harvested for histomorphometrical analysis and RT-PCR (Genes of interest: Collagen I, DMP1, DSPP, TGF ß1, RANKL and OPG). Histomorphometric analysis showed no significant difference among the five groups in the odontoblast count and predentin thickness. RT-PCR demonstrated no expression of TGF ß1, low amounts of DSPP, a twofold increase in collagen I expression in the 5- and 10-minute LIPUS groups and a threefold increase in DMP1 expression in the 10-minute LIPUS group. LIPUS application was stimulatory to the dentin-pulp complex in vitro and increased the expression of collagen I and DMP1.

Long term effect of low intensity pulsed ultrasound on a human tooth slice organ culture.

OBJECTIVE: Investigate the effect of therapeutic Low Intensity Pulsed Ultrasound (LIPUS) on human dentine-pulp complex in an in vitro model. DESIGN: 92 premolars were extracted from 23 adolescent orthodontic patients. The premolars were sectioned transversely into 600 µm thick slices. The slices were divided into two main groups according to how often the LIPUS was applied (single or daily application), and then subdivided into five subgroups each (5, 10, 15 and 20 min and one control group). The tooth slices were cultured at (37 °C/5% CO(2)) in a humidified incubator where medium was changed every 48 h. LIPUS was applied using a 3.9 cm(2) transducer that produces an incident intensity of 30 mW/cm(2). After five days, tissue was harvested for histomorphometrical analysis and real time PCR to investigate expression of genes of interest (Collagen I, DMP1, DSPP, TGF-ß1, RANKL and OPG). RESULTS: Histomorphometric analyses revealed that odontoblast cell count was higher in the single application groups (5, 10 and 15 min, respectively) than in the control and other treatment groups. Predentin thickness was higher in the single application group (10, 5 and 15 min) respectively than in the daily application group and the control groups, however they were not significantly different from each other. Real time PCR demonstrated no statistically significant difference between the groups in the expression of Collagen I, DMP1, TGF-ß1, DSPP, RANKL and OPG. CONCLUSION: Reproducible responses from cultured dentine-pulp complex were observed in groups with single application of LIPUS for 5, 10 and 15 min.

Long-term stability after craniofacial distraction osteogenesis.

PURPOSE: This study was conducted to systematically review long-term skeletal stability after craniofacial distraction osteogenesis. MATERIALS AND METHODS: Several electronic databases (Old Medline, Medline, Medline In-Process and Other Non-Indexed Citations, Pubmed, Embase, Web of Science, and all EBM reviews [Cochrane Database of Systematic Reviews, ACP Journal Club, DARE, and CCTR]) were searched. Key words used in the search were "distraction," "osteogenesis," "craniofacial," "maxillofacial," "stability," "relapse," and "recurrence." MeSH terms and truncations of these terms were selected with the help of a health science librarian. Abstracts that appeared to contain at least 3 years of postsurgical data were selected. The original articles were then retrieved and evaluated to ensure that they actually had 3 years of data after craniofacial distraction osteogenesis. The references were also hand-searched for possible missing articles that were not indexed in the searched databases. RESULTS: A total of 118 abstracts were found in the electronic searches. After the first set of selection criteria was applied on these abstracts, 22 articles were retrieved. After the final selection criteria were applied on these 22 articles, only 6 articles were finally selected. These 6 articles reported long-term stability after craniofacial distraction osteogenesis. Sample sizes were small, and the methodological quality of the studies was poor. CONCLUSIONS: Although, based on the selected studies, craniofacial bone distraction osteogenesis appeared to show long-term stability; limitations of the studies merit caution in interpreting these findings. Some early relapse occurred in the first 3 years postdistraction, but stability was maintained thereafter. Some methodologically sounder studies are needed to confirm the present findings.