Jaakko Peltola

Dosimetry and image quality of four dental cone beam computed tomography scanners compared with multislice computed tomography scanners

OBJECTIVES The aim of this study was to evaluate the radiation dose and image quality of four dental cone beam CT (CBCT) scanners, and to compare them with those of two multislice CT (MSCT) scanners. METHODS Tissue doses were measured using a tissue-equivalent anthropomorphic RANDO Head Phantom((R)) with thermoluminescence dosemeters (TLD). An RSVP Head Phantom(TM) with a specially designed cylindrical insert was used for comparison of image quality and absorbed dose. Image quality was evaluated in the form of contrast-to-noise ratio (CNR) and modulation transfer function (MTF). RESULTS Using standard imaging parameters, the effective doses varied between 14 microSv and 269 microSv (International Commission on Radiation Protection (ICRP) 1990) and 27 microSv and 674 microSv (ICRP 2008) with the CBCT scanners, and between 350 microSv and 742 microSv (ICRP 1990) and 685 microSv and 1410 microSv (ICRP 2008) with the MSCT scanners. The CNR of the CBCT and MSCT scanners were 8.2-18.8 and 13.6-20.7, respectively. Low-dose MSCT protocols provided CNRs comparable with those from CBCT scanners. The 10% MTF of the CBCT scanners varied between 0.1 mm(-1) and 0.8 mm(-1), and was 0.5 mm(-1) for all the MSCT protocols examined. CONCLUSIONS CBCT scanners provide adequate image quality for dentomaxillofacial examinations while delivering considerably smaller effective doses to the patient. Large variations in patient dose and image quality emphasize the importance of optimizing imaging parameters in both CBCT and MSCT examinations.

Accuracy of linear measurements using dental cone beam and conventional multislice computed tomography

OBJECTIVES The aim of this study was to evaluate the accuracy of linear measurements obtained with dental cone beam CT (CBCT) and multislice CT (MSCT) by altering radiation doses using pre-operative planning of the placement of oral implants as a model. METHODS A human cadaver mandible was examined in two edentulous areas and one dentate area using CBCT and MSCT. The mandible was examined both dry and immersed in sucrose solution isointense with soft tissue. Two readers measured four linear distances twice from each section. The mandible was cut into 4 mm thick slices at three marked places. These slices were microradiographed and used as the gold standard for measurements from each section. RESULTS The intraclass correlations between the intra- and interobserver readings obtained with the different methods showed almost perfect matches. The measurement error (ME) showed significant differences between the methods studied (P = 0.022): the mean ME was 4.7% for CBCT and 8.8% for MSCT of the dry mandible, 2.3% and 6.6%, respectively, for the mandible immersed in sucrose solution and 5.4% for low-dose MSCT. Lowering the MSCT radiation dose to less than a quarter of its conventional original value did not significantly affect the ME. CONCLUSIONS CBCT is a reliable tool for implant-planning measurements when compared with MSCT. In this study, a considerable radiation dose reduction could be achieved with low-dose MSCT examinations without a major loss of measurement accuracy.

Disturbed root development of permanent teeth after pediatric stem cell transplantation. Dental root development after SCT

Deficient dental root development has been reported after conventional pediatric anticancer therapy, but less information is available on stem cell transplantation (SCT) recipients.

Reliability of CBCT and other radiographic methods in preoperative evaluation of lower third molars

OBJECTIVES The aim of this study was to compare the reliability of cone-beam computerized tomography (CBCT) with that of other radiographic methods in preoperative radiographic determination of the number of roots of lower third molars and their relationship to the inferior alveolar canal (IAC). STUDY DESIGN Forty-two teeth were clinically studied and imaged using CBCT and other imaging methods-panoramic radiography, multiprojection narrow-beam radiography (MNBR), and cross-sectional tomography. Statistical analysis (kappa values) was used to compare the diagnoses of 2 trained oral radiologists and the radiologic diagnoses with the findings at operation. RESULTS Cone-beam CT revealed the number of roots of teeth more reliably than panoramic radiographs. CBCT examination was highly reliable in locating the IAC, whereas MNBR was unreliable and cross-sectional tomography fell between the two. With cross-sectional tomography, the IAC was noninterpretable in one-third of the cases. CONCLUSIONS We recommend CBCT examination for preoperative radiographic evaluation of complicated impacted lower third molars.

Agenesis and microdontia of permanent teeth as late adverse effects after stem cell transplantation in young children

The objective of the current study was to examine the occurrence of tooth agenesis and microdontia in pediatric stem cell transplantation (SCT) recipients.

Radiofrequency surgery of the soft palate in the treatment of mild obstructive sleep apnea is not effective as a single-stage procedure: A randomized single-blinded placebo-controlled trial.

Radiofrequency (RF) surgery of the soft palate (SP) is an established treatment option for the treatment of snoring. Due to its minimally invasive character, it has received attention in the management of mild obstructive sleep apnea syndrome (OSAS).

DLX3 Homeodomain Mutations Cause Tricho-Dento-Osseous Syndrome with Novel Phenotypes

Tricho-dento-osseous syndrome (TDO) is a rare type of dominantly inherited ectodermal dysplasia so far described only in a few families and associated with 3 known mutations in the DLX3 homeobox gene. Here, we describe two families of Finnish origin that segregate features of TDO in several generations. The affected family members have sparse or curly/kinky hair at birth, markedly delayed or advanced dental maturity, defective tooth enamel and dentin, taurodontic molars, multiple dental abscesses and filling of tooth pulps with amorphous denticle-like material as well as an increased density and/or thickness of craniofacial bones. The disease is especially accentuated in one of the families in which the patients develop only lanugo-type hair and the dental abnormalities are severe. After mutational analysis of DLX3, we identified 2 missense mutations affecting the conserved homeodomain. We suggest that TDO is essentially caused by loss of function and haploinsufficiency of DLX3.

A Follow-up Study of Radiographic Findings in the Mandibular Condyles of Orthodontically Treated Patients and Associations with TMD

Our earlier studies have shown that some radiographic structural findings in the mandibular condyles are more common in orthodontically treated populations than in normal populations. To test the hypothesis that these findings are stable, we studied condylar findings in panoramic radiographs longitudinally in 39 subjects and in 39 sex- and age-matched controls. The subjects had condylar findings at the end of orthodontic treatment at about 15 years of age; no such findings were seen in the controls. The subjects and controls were re-examined radiographically about 12 years after the posttreatment radiographic examination. We also tested the hypothesis that radiographic condylar findings are associated with temporomandibular disorders (TMD). No statistically significant differences were found between subjects and controls in terms of reported subjective TMD symptoms. Clinically, the subjects had temporomandibular joint (TMJ) crepitation significantly more frequently (27%) than controls (8%) (p < 0.05). Crepitation correlated with some reported symptoms and clinical signs, suggesting that osteoarthrosis might have been an important etiological factor for TMD in the present subjects. At the follow-up examination, radiographic condylar findings were seen in 25 subjects and in four controls (p < 0.001). The condylar findings varied greatly between the time of orthodontic treatment and follow-up in the subjects. The findings had become more severe in 49% of the subjects, more often in females than in males (p < 0.05), whereas in 28% of the subjects the condylar findings had disappeared. Although the radiographic findings after orthodontic treatment fluctuated with age, in most adolescents with changes in their condyles, these findings remained constant or became more severe. It should be emphasized, however, that although there were certain associations between radiographic findings and TMD, the subjective symptoms and clinical signs seemed to cause the subjects no or only minor problems.

Timing of developmental stages in permanent mandibular teeth of Finns from birth to age 25.

Objective. The aim was to provide radiographic data on postnatal development of the 8 mandibular teeth to serve as reference norms in clinical dentistry, forensic dentistry, anthropology, and research. Material and Methods. Developmental stages of teeth were assessed from a total of 2795 radiographs, mostly panoramic, of 1970 Finns (966 M and 1004 F) from birth to age 25. The grading was based on Demirjians 8 mineralization stages and the crypt stage. Results. Timing of development in individual mandibular teeth is presented in two ways: as age at attainment of each developmental stage and as age of subjects in a developmental stage. Initiation of mineralization was visible in 1st molars at 0.20 years, in central incisors at 0.22 years, lateral incisors at 0.37 years, and canines at 0.56 years of age. Timing was usually earlier in girls than in boys. Differences were greatest in canines, where females were advanced by 1.74 years at the closure of the apex. Root development in 3rd molars showed an opposite trend, where apical closure was 1.19 years earlier in men. In 3rd molars, age at apical closure in females was 21.50 years, among the highest reported. In general, the early developmental stages had the shortest duration and the last stages the longest. Conclusion. Timing of postnatal development of individual mandibular teeth in Finns resembled developmental schedules reported for other Caucasian population groups. Any differences were mostly small and inconsequential.OBJECTIVE The aim was to provide radiographic data on postnatal development of the 8 mandibular teeth to serve as reference norms in clinical dentistry, forensic dentistry, anthropology, and research. MATERIAL AND METHODS Developmental stages of teeth were assessed from a total of 2795 radiographs, mostly panoramic, of 1970 Finns (966 M and 1004 F) from birth to age 25. The grading was based on Demirjians 8 mineralization stages and the crypt stage. RESULTS Timing of development in individual mandibular teeth is presented in two ways: as age at attainment of each developmental stage and as age of subjects in a developmental stage. Initiation of mineralization was visible in 1st molars at 0.20 years, in central incisors at 0.22 years, lateral incisors at 0.37 years, and canines at 0.56 years of age. Timing was usually earlier in girls than in boys. Differences were greatest in canines, where females were advanced by 1.74 years at the closure of the apex. Root development in 3rd molars showed an opposite trend, where apical closure was 1.19 years earlier in men. In 3rd molars, age at apical closure in females was 21.50 years, among the highest reported. In general, the early developmental stages had the shortest duration and the last stages the longest. CONCLUSION Timing of postnatal development of individual mandibular teeth in Finns resembled developmental schedules reported for other Caucasian population groups. Any differences were mostly small and inconsequential.

Radiographic findings in the teeth and jaws of 14- to 17-year-old Estonian schoolchildren in Tartu and Tallinn

Panoramic radiographs were taken of 392 Estonian schoolchildren (33% boys and 67% girls) aged 14-17 years, 197 in Tartu and 195 in Tallinn. The mean number of permanent teeth was 31.5. In 14% of the children one to four teeth (excluding wisdom teeth) were missing. The frequencies of missing wisdom teeth and supernumerary teeth agreed with those in the literature, being 17% and 3%, respectively. The mean number of radiographically detected carious teeth was 1.9 in Tartu and 3.3 in Tallinn. Secondary caries was common, being found radiographically in half of the schoolchildren. Endodontic treatment had been given to 13% of the subjects in Tartu and to 46% in Tallinn, the success rates being 47% and 44%, respectively. The percentage of radiographic signs in the mandibular condyles of girls (5%) was greater than that of the boys (1%). Changes in the maxillary sinuses were found in 16% of the children. Eight odontogenic cysts, one cyst of the incisal canal, and one solitary bone cyst were found. Tumors included two odontomas, two cemento-ossifying lesions, and one osteoma in the maxillary sinus. The health status of the jaws of the Estonian schoolchildren was considered to be fairly good.