Radiographs and skeletal development
Panoramic and intraoral radiographs can be used as a first diagnostic tool to estimate skeletal maturation, report scientists publishing in the April 2016 issue of the American Journal of Orthodontics and Dentofacial Orthopedics. Such findings are important because they mean that patients may need fewer radiographs during treatment, reducing both costs and radiation exposure.
Clinicians know that accurate evaluation of developmental stage is critical in determining the optimal time for treatment of pediatric patients, particularly in relation to periods of accelerated growth. However, because of variations in the timing of the pubertal growth spurt (PGS), chronological age is not a good indicator of skeletal maturation. Although high correlations have been reported in previous research comparing dental and skeletal maturation, such correlation is not satisfactory for diagnostic identification of skeletal maturation stage.
That is why scientists in Brazil sought to pair teeth with corresponding mineralization stages and different stages of skeletal maturation. The scientists’ focus was on identifying the PGS. Mineralization stages of the teeth were selected over eruption stages in the study design, because previous research had proposed that tooth formation was a more reliable criterion for determining dental maturation.
To explore, the scientists analyzed relevant associations between dental development and skeletal maturation using both panoramic and hand-wrist radiographs in 491 participants (222 boys and 269 girls aged 7-17 years). Examined teeth included the mandibular left canine, first and second premolars, and second molar. Skeletal maturation was assessed according to the 14 stages of bone ossification.
Among the results, scientists found that a consistently earlier occurrence for each skeletal maturation stage was observed in girls than in boys. In fact, the mean chronological age of girls for such staging was approximately 1.8 years younger than that of the boys.
The second premolars were the best predictors for maturation stages for both sexes, while the first premolars were statistically significant for girls and the canines and second premolars were demonstrated predictors of skeletal maturation for boys.
In the discussion, the study’s authors noted that previous research showed that boys tended to have more advanced tooth development when compared with girls regarding the skeletal maturation stages. “This could be explained by the later occurrence of skeletal maturation in boys than in girls,” scientists asserted. “Therefore, a sex distinction must be contemplated when estimating facial growth according to dental maturation.”
Authors said their results support a significant association between the dental maturation stages of some teeth and the skeletal maturation periods that can lead clinicians to identify PGS with panoramic or intraoral radiographs.
Among the conclusions, researchers asserted that because dental mineralization stages can be used to estimate the skeletal maturation period, panoramic and intraoral radiographs could be used to reduce the requirement for hand-wrist radiographs or suggest the ideal time for them to be obtained.
Read the original article.
Consulting Editor: Laurie C. Carter, DDS, PhD
Past president, American Academy of Oral and Maxillofacial Radiology
CBCT for dental indications plays role in bone disease screening
Cone-beam computed tomographic (CBCT) scans obtained for dental purposes may play an important role in osteoporosis screening and referral, according to a report in the November 2015 issue of Oral Surgery, Oral Medicine, Oral Pathology and Oral Radiology.
The silent nature of osteoporosis often delays diagnosis. Characterized by low bone mass, deterioration of the bone structure, and increased risk of fracture, the financial burden of this skeletal disease and its effect on quality of life are substantial. Research shows that patients with osteoporosis also may have higher failure rates of dental implants, according to the report.
Dental radiographs used for diagnoses of conditions affecting teeth and jaws reportedly may offer an opportunity to detect osteoporosis and have been suggested as a screening tool for the disease. Considering that bone quality is best assessed if more of its characteristics are quantified and that CBCT provides information on assessment of bone quality, a team of scientists in Syria and the UK conducted a study. They sought to evaluate the ability of CBCT images to predict osteoporosis from the cervical vertebrae CBCT-derived radiographic density (RD) values. The study was conducted with menopausal and postmenopausal women using the CBCT viewer program. The observational cross-sectional design used dual-energy X-ray absorptiometry and CBCT images of 38 women who had participated in a larger study on jawbone changes and osteoporosis.
Among the findings, there were statistically significant differences in the values among the 3 groups (healthy women, women with osteopenia, and women with osteoporosis), whether classified according to lumbar vertebrae or femoral neck T-scores. Thus, results showed cervical vertebrae CBCT-derived RD values could predict osteoporosis status in menopausal and postmenopausal women with use of the associated CBCT viewer program.
Authors said their findings could be considered an important step in the collaboration among health care professionals to diagnose osteoporosis. “Dentists can use CBCT images, exposed for appropriate diagnostic reasons, as an opportunistic screening tool for osteoporosis without the need for additional expensive and complicated programs or calibration phantoms.”
In the discussion, authors also said the study findings could help in distinguishing healthy women, women with osteopenia, and women with osteoporosis on the basis of cervical vertebrae CBCT-derived RD values. “Thus, the present study demonstrated the possibility of identifying patients with osteopenia, going a step beyond previous research, which had aimed to develop a primary threshold to distinguish only between healthy women and those with osteoporosis.”
Including a tool within the CBCT viewer software that might automatically calculate the cervical vertebrae RD values and alert the dentist about referral when the possibility of osteoporosis is indicated would be supported by this research, authors noted.
Read the original article.
Evaluating the mental foramen with CBCT
A study evaluating the variations of mental foramina by cone-beam computed tomography (CBCT) demonstrated the significance of preoperative radiographic examinations, particularly 3-dimensional images, in determining anatomic variations.
The mental foramen allows passage of the mental nerves and vessels. Accurate identification of its clinical location can prevent surgical nerve damage and aid in the successful administration of local anesthetic. Oval or circular, it cannot be seen or touched clearly. It is the subject of many studies, and the literature shows differences from 1 race to another.
Finding a lack of research on the position and direction of the mental foramen in an Iranian population, scientists in Iran, who were interested in investigating all variations among Iranians, conducted a study. They evaluated the shape, size, direction, and horizontal and vertical positions using CBCT and reported their findings online November 2 in Radiology Research and Practice.
Two examiners analyzed 180 CBCT images in different planes taken from 2010 to 2015 for diagnostic purposes in the Department of Maxillofacial Radiology at Isfahan School of Dentistry. They identified mental foramina in cross-sectional and axial views to determine the shape, diameter, and direction of the openings.
In 84 images of men and 96 of women, the mental foramen was present in both sides on all images. Among the results of their study, researchers found that mental foramina were oval-shaped twice as often as they were round-shaped. The shape of the mental foramen was the same in both sides in more than 82% of images.
Mental foramen size was 3.59 millimeters in diameter and similar to that reported in the literature in a white population. The opening direction was superior-posterior (the most common direction reported in previous research among a white population was posterior).
Study results upheld previous research showing that location differed according to race. The most common horizontal locations were in line with the second premolar and between the first premolar and second premolar.
In discussion, authors noted the much-reported differences in mental foramina shapes between races. For example, most Indians have been reported to have round mental foramina, whereas Malawians have mostly oval-shaped mental foramina. Among Tanzanian and Zimbabwean populations, round and oval shapes have been reported in about equal in number.
Within the discussion, authors also said that determining the position from adjacent teeth has its limitations, particularly for patients receiving implants who are partially or fully edentulous and have lost molars and premolars. The authors recommended further studies to analyze other landmarks, such as the inferior border of the mandible, to better determine position.
In the conclusions, the authors stated the most common variation of mental foramina in the Iranian population studied was oval-shaped, superior-posterior opening, apical to the apex, and in line with a second premolar. “However, other types of mental foramen variables exist, reflecting the significance of preoperative radiographic examinations, especially 3D images (CBCT),” they said. “These findings can help in safe implant surgery and administration of successful local anesthesia.”
Read the original article.
CBCT and mandibular third-molar extraction
Scientists in the Netherlands interested in research to address 1 of the most distressing complications after mandibular third-molar extraction—damage to the inferior alveolar nerve (IAN)—conducted a randomized controlled trial and published their findings in the December 2015 issue of Journal of Cranio-Maxillofacial Surgery.
The most predictive factor for IAN damage is the proximity of the third-molar root to the mandibular canal (MC). Preoperative assessment of the position and the relationship of the third molar with the MC can minimize the risk of nerve injury. Although panoramic radiography (PR) is the standard diagnostic imaging modality for this purpose, cone-beam computed tomography (CBCT) is increasingly used for a 3-dimensional preoperative assessment of the relationship between the third molar and the MC. However, it is important to weigh the potential benefits of using CBCT against the higher costs and the risk of extra radiation exposure, especially in young patients, according to recent research.
Finding limited research on the efficacy of CBCT for impacted teeth and the potential benefits of CBCT on patient outcomes, as well as conflicting data on the incidence of IAN injury after third-molar extraction, scientists conducted a study. They investigated the effectiveness of CBCT compared with PR on the degree of patient morbidity for this commonly performed surgical procedure to test the hypothesis: CBCT is superior compared with PR in reducing the risk of IAN injury and other complications after the removal of mandibular third molars in patients at increased risk of IAN injury.
Three departments of Oral and Maxillofacial Surgery in the Netherlands participated. Adults having 1 or 2 mandibular third molars with a close relationship with the MC were eligible for the study.
A total of 268 patients with 320 mandibular molars were allocated to 1 of 2 groups. The PR group participants received only digital PR, which was made for assessment of eligibility. In the CBCT group, in addition to PR, a high density resolution mandibular scan was also acquired before surgery.
All surgeons were experienced in the assessment of CBCT and PR images. Mandibular third molars were removed under local anesthesia. Surgical variables, such as experience of the surgeon and duration of surgery were recorded.
The primary outcome measure was the number of patients reporting pain at 1 week after surgery. As secondary outcome measures, the number of patients with objective IAN injury, a long-term (> 6-month) IAN injury, other postoperative complications, Oral Health Related Quality of Life–14 questionnaire responses, postoperative pain, duration of surgery, number of emergency visits, and number of days missed from work or study were scored. Incidence of injury after 1 week was 6.3%. No significant differences between CBCT and PR for temporary injury (the primary outcome) or all secondary outcomes were reported.
However, CBCT did prove to be superior compared with PR for selecting high-risk patients. A lingual position and narrowing of the MC at the contact area between the MC and the roots were strong risk factors for a temporary IAN injury.
“Although CBCT is a valuable diagnostic adjunct for identification of an increased risk for IAN injury, the use of CBCT does not translate into a reduction of IAN injury and other postoperative complications, after removal of the complete mandibular third molar,” authors reported among conclusions. They also asserted that when PR “indicates a substantial risk for IAN injury, consideration should be given to more conservative strategies such as monitoring or coronectomy, rather than outright third-molar extraction.”
Read the original article.
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What is Specialty Scan?
This is one in a series of quarterly newsletters updating dentists on selected specialties in dentistry. Information presented is aggregated and summarized from previously published materials, each item attributed to its publication of origin. This issue of JADA Specialty Scan focuses on oral and maxillofacial radiology, the second in the series on this topic for 2016. Other Specialty Scan issues are devoted to endodontics, oral pathology, orthodontics, periodontics and prosthodontics. The ADA has engaged the specialty organizations in these areas as well as its own Science Institute and Division of Legal Affairs to assist with these newsletters. We welcome feedback on this and all Specialty Scan issues.
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