Optimizing radiation safety in dentistry: Clinical recommendations and regulatory considerations.

BACKGROUND: The value of dental radiographs to oral health care decision making must be balanced with radiation safety to minimize patient exposure and occupational risk of oral health care providers. This review summarizes recommendations and regulatory guidance regarding dental radiography and cone-beam computed tomography. An expert panel presents recommendations on radiation safety, appropriate imaging practices, and reducing radiation exposure. TYPES OF STUDIES REVIEWED: A systematic search run in Ovid MEDLINE, Embase, and Cochrane Database of Systematic Reviews identified relevant topical systematic reviews, organizational guidelines, and regulatory reviews published in the peer-reviewed literature since 2010. A supplemental search of the gray literature (eg, technical reports, standards, and regulations) identified topical nonindexed publications. Inclusion criteria required relevance to primary oral health care (ie, general or pediatric dentistry). RESULTS: A total of 95 articles, guidance documents, and regulations met the inclusion criteria. Resources were characterized as applicable to all modalities, operator and occupational protection, dose reduction and optimization, and quality assurance and control. PRACTICAL IMPLICATIONS: Understanding factors affecting imaging safety and applying fundamental principles of radiation protection consistent with federal, state, and local requirements are essential for limiting patient ionizing radiation exposure, in conjunction with implementing optimal imaging procedures to support prudent use of dental radiographs and cone-beam computed tomographic imaging. The regulatory guidance and best practice recommendations summarized in this article should be followed by dentists and other oral health care providers.

A cone beam computed tomographic analysis of cervical vertebral nonsegmentation.

OBJECTIVE: Using cone beam computed tomography (CBCT), this study aimed to investigate the radiologic features of cervical vertebral nonsegmentation (CVN) in patients with no known syndromes or pathoses. STUDY DESIGN: In this retrospective study, we examined CBCT scans of patients with CVN for the following parameters: type of nonsegmentation (partial or complete); laterality of partial nonsegmentation; level of vertebrae affected in nonsegmentation; anatomic parts of the vertebrae involved; and the presence or absence of degenerative joint disease (DJD). RESULTS: From the structured reports of 13,458 CBCT scans, we found 110 CBCT scans (0.82%) with CVN. Of this total, 77.3% were partial and 22.7% were complete. Most were located at the level of the C2 and C3 vertebrae. The transverse process alone and the transverse process and body were most frequently involved in partial CVN, whereas most complete types occurred in the transverse process and body. Degenerative joint disease was present in 45.9% of partial CVN (clearly distinguishable from nonsegmentation in 36.5%) and 20% of complete CVN, with all cases clearly distinguishable. CONCLUSIONS: Cervical vertebral nonsegmentation has a low prevalence. It is mostly partial, occurs most commonly in C2-C3, and usually involves the transverse process and body. Identification of CVN on CBCT images is important because this condition can lead to DJD in older age and may increase the risk for muscle weakness, head and neck pain, limited movement, and neurologic complications.

Morphological integration in inferior alveolar canal and mandibular shapes.

OBJECTIVE: During embryogenesis of mandible, the initial ossification centre begins at the bifurcation of the inferior alveolar (IA) and the mental nerves. Additionally, in congenital anomalies like craniofacial microsomia (CFM), the IA canal is completely absent on the microsomic side. These observations led us to hypothesise that there may be a morphological integration between these structures - the IA nerve and the mandibular shapes. Therefore, the primary objective of this study was to test for morphological integration between these structures and the secondary objective was to determine if there were shape variations in these structures among skeletal Classes I, II and III subjects. SETTING AND SAMPLE POPULATION: The sample size of the study is 80 full-head cone-beam computed tomography (CBCT) scans (age 16-56 years). METHODS: We retrieved CBCT scans from our archived database using specific inclusion/exclusion criteria. In the de-identified CBCT scans, traditional coordinate landmarks and sliding semi-landmarks were placed on the mandible and the IA canal (proxy for IA nerve). Using geometric morphometric analyses, we tested integration between the IA canal and the mandibular shapes. We used Procrustes ANOVA to test for overall shape variations among the three skeletal classes (Classes I, II and III). RESULTS: The IA canal and posterior/inferior border of mandible showed strong integration (r-PLS = .845, P = .001). Similar strong integration was also observed between the IA canal and the overall shape of the mandible (r-PLS = .866, P = .001). Additionally, there was a statistically significant variation in overall shape between skeletal Class I and Class II (P = .008) and Class II and Class III (P = .001). CONCLUSIONS: The strong integration between two structures suggests that the IA nerve may play a role in establishing mandibular shape early in development. We posit this may be important in driving mandibular defects seen in CFM, which warrants further investigation.

Alveolar ridge preservation reduces the need for ancillary bone augmentation in the context of implant therapy.

BACKGROUND: There is limited information on the need for bone augmentation in the context of delayed implant placement whether alveolar ridge preservation (ARP) is previously performed or not. The primary aim of this retrospective cohort study was to evaluate the efficacy of ARP therapy after tooth extraction compared with unassisted socket healing (USH) in reducing the need for ancillary bone augmentation before or at the time of implant placement. METHODS: Adult subjects that underwent non-molar single tooth extraction with or without simultaneous ARP therapy were included in this study. Cone beam computed tomography scans obtained before tooth extraction and after a variable healing period were used to record the baseline facial bone thickness and to virtually plan implant placement according to a standard method. A logistic regression model was used to evaluate the effect of facial alveolar bone thickness upon tooth extraction and baseline therapy (USH or ARP) on the need for additional bone augmentation, adjusting for several covariates (i.e., age, sex, baseline KMW, and tooth type). RESULTS: One hundred and forty subjects that were equally distributed between both baseline therapy groups constituted the study population. Implant placement was deemed virtually feasible in all study sites. Simultaneous bone augmentation was considered necessary in 60% and 11.4% of the sites in the USH and ARP group, respectively. Most of these sites (64.2% in the USH group and 87.5% in the ARP group) exhibited a thin facial bone phenotype (<1 mm) at baseline. Logistic regression revealed that the odds of not needing ancillary bone augmentation were 17.8 times higher in sites that received ARP therapy. Furthermore, the need for additional bone augmentation was reduced 7.7 times for every 1 mm increase in facial bone thickness, regardless of baseline therapy. CONCLUSIONS: Based on a digital analysis, ARP therapy, compared with USH, and thick facial alveolar bone largely reduce the need for ancillary bone augmentation at the time of implant placement in non-molar sites.

Evaluation of poly lactic-co-glycolic acid-coated ß-tricalcium phosphate for alveolar ridge preservation: A multicenter randomized controlled trial.

BACKGROUND: Alveolar ridge preservation via socket grafting (ARP-SG) is indicated to attenuate physiologic alveolar bone resorption as a consequence of tooth extraction. However, a specific bone grafting material that is patently superior has not been identified yet. The aim of this randomized controlled trial was to evaluate the efficacy of a moldable alloplastic graft, Poly Lactic-Co-Glycolic Acid-Coated ß-Tricalcium Phosphate (PLGA-ß-TCP), for ARP purposes [Group A] compared to freeze-dried bone allograft (FDBA) particles covered with a rapidly absorbable collagen dressing (RACD) (Group B) in function of a panel of radiographic, histomorphometric, and implant-related outcomes. METHODS: Patients in need of extraction of a single posterior tooth (premolar or molar) and subsequent replacement with a dental implant were recruited and randomly allocated into one of the two treatment groups. Follow-up visits took place at 1, 2, 4, 8, and 16 weeks. Cone-beam Computed Tomography (CBCT) scans were obtained at baseline and at 16 weeks. Sites were re-entered at 20 weeks for bone core biopsy harvesting and subsequent implant placement. After delivery of the final implant-supported restoration, follow-up visits were scheduled at 6 and 12 months to monitor peri-implant tissue health and marginal bone levels using standardized intraoral periapical radiographs. RESULTS: A total of 45 patients were initially enrolled in the study, of whom 43 received an implant and 32 completed the study. Healing was uneventful in all sites after ARP-SG and implant placement. No site required bone augmentation to allow for implant placement. CBCT scan analyses showed no statistically significant differences between groups in terms of reduction of horizontal width, midbuccal / midlingual height and ridge volume. Histomorphometric assessments revealed a statistically significant difference between both groups in terms of mineralized tissue formation (Group A = 27.0% ± 22.1% versus Group B = 38.2% ± 12.5%; P < 0.05). On the contrary, no significant differences were observed regarding percent of remaining bone grafting material and non-mineralized tissue. No implant failed throughout the study period and marginal bone level change was negligible in both groups. CONCLUSIONS: Although a higher proportion of mineralized tissue was associated with the use of FDBA+RACD compared to PLGA-ß-TCP alone, both ARP-SG approaches rendered comparable outcomes in terms of maintenance of alveolar bone dimensions, feasibility of implant placement, implant survival, and peri-implant bone level stability up to 12 months post-loading.

Three-Dimensional Assessment of Cervical Vertebrae Anomalies in Patients With Cleft Lip and Palate.

OBJECTIVE: To evaluate the occurrence of cervical vertebrae anomalies (CVA) in patients with unilateral (UCLP) and bilateral cleft lip and palate (BCLP) using cone beam computed tomography (CBCT) examinations. DESIGN: Retrospective assessment of CBCT images. Descriptive statistics were calculated. Fisher exact test or χ2 test was performed to evaluate the differences among each CVA between sex and type of cleft. SETTING: School of Dentistry. PARTICIPANTS: One hundred fifty-one patients with cleft lip and palate (103 UCLP/48 BCLP). INTERVENTIONS: No relevant intervention. MAIN OUTCOME MEASURES: Cone beam computed tomography images were assessed for the presence or absence of 12 most commonly observed CVA: spina bifida, dehiscence, cleft of the posterior arch, cleft of the anterior arch, fusion between cervical vertebrae, block fusion, occipitalization, narrowing of the intervertebral space, posterior ponticle, os odontoideum, ossiculum terminale, and subdental cartilaginous remnants. RESULTS: The presence of subdental cartilaginous remnants was the most frequently observed alteration-found in 81.45% of the sample-and it was the only CVA with statistically significant frequencies in the individuals with BCLP. Considering only the other CVA, 22.51% presented 1 and 5.29% presented 2 or more CVA. CONCLUSIONS: Patients with cleft lip and palate may present an overall high incidence of CVAs. However, when comparing the distribution of the CVAs among sex and types of cleft, the only significant difference noted was a higher incidence of subdental cartilaginous remnants among patients with BCLP.