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Purpose: Ionizing radiation can induce mutations in germ cells in various organisms, including fruit flies and mice. However, currently, there is no clear evidence for the transgenerational effects of radiation in humans. This review is an effort to identify possible reasons for the lack of such observations. Methods: Literature search and narrative review. Results: 1) In both mice and humans, resting oocytes locate primarily in the cortical region of the ovary where the number of blood vessels is very low especially when young and extra-cellular material is rich, and this region is consequently hypoxic, which probably leads to immature oocytes being resistant to the cell killing and mutagenic effects of radiation. 2) In studies of spermatogonia, the mouse genes used for specific locus test (SLT) studies, which include coat color genes, were hypermutable when compared to many other genes. Recent studies which examined over 1000 segments of genomic DNA indicate that the induction rate of deletion mutation per segment was on the order of 10−6 per Gy, which is one order of magnitude lower than that obtained from the SLT data. Therefore, it appears possible that detecting any transgenerational effects of radiation following human male exposures will be difficult due to a lack of mutable marker genes. 3) Fetal malformations were examined in studies in humans, but the genetic component in such malformations is low, and abnormal fetuses are prone to undergo miscarriage which does not occur in mice, and which leads to difficulties in detecting transgenerational effects. Conclusion: The lack of clear evidence for radiation effects in humans probably does not result from any problem in the methodologies used but may be due largely to biological properties. Currently, whole genome sequencing studies of exposed parents and offspring are planned, but ethical guidelines need to be followed to avoid discrimination, which had once happened to the atomic bomb survivors. [ABSTRACT FROM AUTHOR]

Increasing demand for adult orthodontic treatment using clear aligners has highlighted challenges in bonding clear aligner attachments to various restorations. Specifically, the bond strength of clear aligner attachments to glazed monolithic zirconia has not been extensively studied. This study aims to compare the shear bond strength (SBS) and mode of failure (MOF) of conventional bonding methods versus Superbond C&B (4-META/MMA-TBB resin cement) for clear aligner attachments on glazed monolithic zirconia. Fifty sintered and glazed zirconia samples were divided into five groups and attached with clear aligner attachments: Si (silane), B (bonding agent), SiB (bonding agent and silane), SU (Superbond C&B), and SiSU (silane and Superbond C&B). SBS and MOF of these samples were analyzed. Results indicated a significant difference in bond strength among the groups. SiSU exhibited the highest bond strength, followed by SU, while B had the lowest bond strength. SEM analysis revealed that SiSU and SU predominantly exhibited mixed failure, indicating high bond strength without affecting the glazed layers of the zirconia. In contrast, B exhibited only adhesive failure at the interface, resulting in insufficient bond strength for effective orthodontic treatment. In conclusion, using 4-META/MMA-TBB resin cement provides high bond strength for clear aligner attachments on glazed zirconia with minimal material damage during debonding. [ABSTRACT FROM AUTHOR]

Objectives: The purpose of this preliminary study was to determine the differences between planned and actual maxillary molar movements after the completion of treatment with an initial set of clear aligners including sequential maxillary molar distalization. Methods: The data records of 14 non-growing patients who completed orthodontic treatment with sequential maxillary molar distalization using clear aligners were retrospectively evaluated (n= 14, 4 males and 10 females, 33.61 ± 8.57 years). Data on planned tooth movements were obtained from ClinCheck software (ClinCheck Pro version 5.3). The amounts of actual tooth movements were obtained by performing superimposition of lateral cephalograms taken before and after treatment. The amounts of distal translation and tipping between planned and actual maxillary molar movements were compared with the paired Student's t-test. Results: The statistically significant differences between planned and actual translation movements of maxillary first and second molars were shown after completing treatment with the first series of aligners (p < 0.05). The average actual amount of molar distalization on maxillary first molars was less than the planned amount by 1.32 ± 0.42 mm. Similarly, the average actual amount of molar distalization on maxillary second molars was less than the planned amount by 1.57 ± 0.45 mm. The accuracy for molar distalization, namely, the percentage of actual distal translation to planned movement, was 40.11% for maxillary first molars and 35.39% for maxillary second molars. However, the difference between the planned and actual angulation movements was not significant (p > 0.05). Conslusions: In conclusion, the amounts of actual distal translation of maxillary molars through the utilization of clear aligners were significantly lower than planned. However, there were no statistically significant differences between the degrees of actual and planned molar angulation movement. [ABSTRACT FROM AUTHOR]

Background/Objectives: Polysomnography and cephalometry have been used for studying obstructive sleep apnea (OSA) etiology. The association between craniofacial skeleton and OSA severity remains controversial. To study OSA's etiology, cephalometry, fiberoptic pharyngoscopy, polysomnography, and sleep endoscopy have been used; however, airway obstructions cannot be located. Recent research suggested ultrasonography for OSA screening and upper airway obstruction localization. Thus, this study aims to investigate the relationship between specific craniofacial cephalometric and ultrasonic airway parameters in adults at high risk of OSA. Methods: To assess craniofacial structure, lateral cephalograms were taken from thirty-three adults over 18 with a STOP-Bang questionnaire score of three or higher and a waist-to-height ratio (WHtR) of 0.5 or higher. Airway parameters were assessed through submental ultrasound. Results: NSBA correlated with tongue base airspace width, while MP-H correlated with oropharynx, tongue base, and epiglottis airspace width. SNA, SNB, and NSBA correlated with tongue width at the oropharynx. At tongue base, ANB and MP-H correlated with tongue width. SNB and NSBA were associated with deep tissue thickness at the oropharynx, while MP-H correlated with superficial tissue thickness at velum and oropharynx. Conclusions: Cephalometric parameters (SNA, SNB, ANB, NSBA, and MP-H) were correlated with ultrasonic parameters in the velum, oropharynx, tongue base, and epiglottis. [ABSTRACT FROM AUTHOR]

The article focuses on determining the correlation between orthodontically induced root resorption (OIRR) and periodontal ligament (PDL) compression in rats. Topics include assessing PDL compression and OIRR in response to orthodontic force application, investigating the correlation between the extent of PDL compression and OIRR induction at different stages, and comparing the effects of bodily versus tipping tooth movement on OIRR and PDL compression.

Background: Temporary anchorage devices (TADs) are broadly used in orthodontic treatment. TADs must be placed accurately to avoid collision against tooth roots. To place miniscrews with a higher accuracy, a digitally designed surgical guide was proposed in previous studies. However, to our knowledge, there have been no articles that have assessed the minimal required length to achieve good drilling accuracy. The objective of the present study was to evaluate the accuracy of pre-drilling using computer-aided designed surgical guides with different lengths. Methods: A typodont model was scanned, and surgical guides of 3.0, 4.5, and 6.0 mm were designed. Duplicated typodonts and the surgical guides were printed with a 3D printer. Using these models and surgical guides, pre-drillings were performed. Freehand drilling was also conducted for the control. The drilled models were scanned with micro-computed tomography to evaluate the accuracy. Results: The mean errors at the tip of the drill were 0.44 mm, 0.61 mm, 0.41 mm, and 0.24 mm for the freehand drilling, and 3.0, 4.5, and 6.0 mm for the surgical guide, respectively. Conclusion: The results suggested that a longer surgical guide was recommended to achieve good insertion accuracy for a narrow interradicular space, and that 3.0 mm was enough when an error of 1.0 mm was acceptable for the insertion site. [ABSTRACT FROM AUTHOR]