Dental imaging in clinical photon-counting CT at a quarter of DVT dose.

OBJECTIVE: To investigate the image quality of a low-dose dental imaging protocol in the first clinical photon-counting computed tomography (PCCT) system in comparison to a normal-dose acquisition in a digital volume tomography (DVT) system. MATERIALS AND METHODS: Clinical PCCT systems offer an increased spatial resolution compared to previous generations of clinical systems. Their spatial resolution is in the order of dental DVT systems. Resolution-matched acquisitions of ten porcine jaws were performed in a PCCT (Naeotom Alpha, Siemens Healthineers) and in a DVT (Orthophos XL, Dentsply Sirona). PCCT images were acquired with 90 kV at a dose of 1 mGy CTDI16 cm. DVT used 85 kV at 4 mGy. Image reconstruction was performed using the standard algorithms of each system to a voxel size of 160 × 160 × 200 µm. The dose-normalized contrast-to-noise ratio (CNRD) was measured between dentine and enamel and dentine and bone. Two readers evaluated overall diagnostic quality of images and quality of relevant structures such as root channels and dentine. RESULTS: CNRD is higher in all PCCT acquisitions. CNRD is 37 % higher for the contrast dentine-enamel and 31 % higher for the dentine-bone contrast (p < 0.05). Overall diagnostic image quality was higher for PCCT over DVT (p < 0.02 and p < 0.04 for readers 1 and 2). Quality scores for anatomical structures were higher in PCCT compared to DVT (all p < 0.05). Inter- and intrareader reproducibility were acceptable (all ICC>0.64). CONCLUSIONS: PCCT provides an increased image quality over DVT even at a lower dose level and might enable complex dental imaging protocols in the future. CLINICAL SIGNIFICANCE: The evolution of photon-counting technology and it's optimization will increasingly move dental imaging towards standardized 3D visualizations providing both minimal radiation exposure and high diagnostic accuracy.

Long-term stability of splinted anterior mandibular teeth during supportive periodontal therapy.

OBJECTIVE: The aim of the study was to retrospectively assess the survival rate and stability of periodontally compromised and mobile anterior mandibular teeth after splinting in patients under supportive periodontal therapy (SPT). MATERIALS AND METHODS: Thirty-nine patients with splinted anterior mandibular teeth and SPT (≥1 visit/year) for 3-15 years were re-examined. Periodontal status, patient and tooth-related factors were assessed retrospectively before (baseline) and 3 years after splinting (n = 39 patients, 162 splinted teeth). For patients with splints inserted for more than 3 years, retrospective data after 5 (n = 30), 7 (n = 24), 10 (n = 16), 12 (n = 8) and 15 years (n = 4) was included, if available. At baseline, splinted teeth included at least one tooth with increased mobility combined with clinical attachment loss (CAL) ≥ 5 mm and ≥50% relative bone loss (RBL). Baseline RBL of splinted teeth was assessed for all patients. Change in RBL was assessed after 10 years, if available. RESULTS: No splinted tooth was lost within the first 3 years after splinting. One splinted tooth was lost 7 years after baseline and one 12 years after baseline. After 3 years mean(SD) periodontal probing depth of splinted teeth decreased from 3.39(1.41) mm to 2.12(0.37) mm and mean(SD) CAL from 5.61(1.66) mm to 5.09(1.67) mm and remained stable over the observation period. No change in RBL was observed over a 10-year period (p = .213). The survival rate of the splints until fracture or debonding was 74.4% after 3 years. CONCLUSIONS: Periodontally compromised splinted teeth show a high survival-rate and periodontal stability during SPT.