Rapid post-eruptive maturation of porcine enamel.

The teeth of humans and pigs are similar in size, shape, and enamel thickness. While the formation of human primary incisor crowns takes about 8 months, domestic pigs form their teeth within a much shorter time. Piglets are born after 115 days of gestation with some of their teeth erupted that must after weaning meet the mechanical demands of their omnivorous diet without failure. We asked whether this short mineralization time before tooth eruption is combined with a post-eruptive mineralization process, how fast this process occurs, and how much the enamel hardens after eruption. To address this question, we investigated the properties of porcine teeth at two, four, and sixteen weeks after birth (N = 3 animals per time point) through analyses of composition, microstructure, and microhardness. We collected data at three standardized horizontal planes across the tooth crown to determine the change of properties throughout the enamel thickness and in relation to soft tissue eruption. Our findings indicate that porcine teeth erupt hypomineralized compared to healthy human enamel and reach a hardness that is similar to healthy human enamel within less than 4 weeks.

Identification of dental pain sensation based on cardiorespiratory signals.

The aim of this study is to investigate the feasibility of the detection of brief periods of pain sensation based on cardiorespiratory signals during dental pain triggers. Twenty patients underwent dental treatment and reported their pain events by pressing a push button while ECG, PPG, and thoracic effort signals were simultaneously recorded. Potential pain-indicating features were calculated from the physiological data (sample length of 6 s) and were used for supervised learning of a Random forest pain detector. The best feature combination was determined by Feature forward selection. The best feature combination comprises nine feature groups consisting of four respiratory and five cardiac related groups. The final algorithm achieved a sensitivity of 87% and a specificity of 63% with an AUC of 0.828. Using supervised learning it is possible to train an algorithm to differentiate between short time intervals of pain and no pain solely based on cardiorespiratory signals. An on-site and real-time detection and rating of pain sensations would allow a precise, individuum- and treatment-tailored administration of local anesthesia. Severe phases of pain could be paused or avoided, this would allow more comfortable treatment and yield better patient compliance.

Periodontal outcome and additional clinical quality criteria of lithium-disilicate restorations (Empress 2) after 14 years.

OBJECTIVES: To evaluate the clinical quality of tooth-supported crowns (SCs), implant-supported crowns (ISCs), and fixed dental prosthesis (FDPs) made of a lithium-disilicate glass-ceramic framework material (IPS Empress 2, Ivoclar Vivadent) after long-term use. MATERIALS AND METHODS: Between 1997 and 1999, 184 restorations (106 SCs, 32 ISCs, 33 FDPs, 13 diverse restorations) were placed in 73 patients. In 2012/2013, all patients with functioning restorations were invited to participate in a clinical follow-up examination. To investigate the clinical quality, modified California Dental Association (CDA) criteria, periodontal health, and the patient's opinion were evaluated. RESULTS: After 14 years on average, 50 restorations were available for evaluation of the CDA criteria and the patient's opinion, and 24 restorations were available for the periodontal health evaluation. Surface, color, anatomic shape, and margin integrity were considered to be in the range of excellence in 54, 78, 96, and 88%, respectively. There were no unacceptable defects. Most patients (64%) were still entirely satisfied with their restorations. Mean probing depths were significantly higher on teeth with tooth-supported Empress 2 restorations than on control teeth (p = 0.0401). No significant relationship was found between surface quality and plaque accumulation (p = 0.9450, generalized linear mixed model) or between surface quality and periodontal probing ≥ 4 mm (p = 0.4184, generalized linear mixed model). CONCLUSIONS: The clinical quality of the Empress 2 restorations that had survived 14 years on average was totally satisfactory with regard to esthetics, design, and patient's opinion. The periodontal health of all-ceramic restored teeth requires further investigation. CLINICAL SIGNIFICANCE: The practitioner's choice of dental materials is based, at best, on long-term experience. With diminishing concerns about the clinical longevity of all-ceramic restorations, the grading of clinical quality based on esthetics, design, periodontal response, and patients' opinions could, nowadays, serve as a measure for the efficiency of dental ceramic.

Detection of acute periodontal pain from physiological signals.

OBJECTIVE: To investigate the feasibility of the detection of brief orofacial pain sensations from easily recordable physiological signals by means of machine learning techniques. APPROACH: A total of 47 subjects underwent periodontal probing and indicated each instance of pain perception by means of a push button. Simultaneously, physiological signals were recorded and, subsequently, autonomic indices were computed. By using the autonomic indices as input features of a classifier, a pain indicator based on fusion of the various autonomic mechanisms was achieved. Seven patients were randomly chosen for the test set. The rest of the data were utilized for the validation of several classifiers and feature combinations by applying leave-one-out-cross-validation. MAIN RESULTS: During the validation process the random forest classifier, using frequency spectral bins of the ECG, wavelet level energies of the ECG and PPG, PPG amplitude, and SPI as features, turned out to be the best pain detection algorithm. The final test of this algorithm on the independent test dataset yielded a sensitivity and specificity of 71% and 70%, respectively. SIGNIFICANCE: Based on these results, fusion of autonomic indices by applying machine learning techniques is a promising option for the detection of very brief instances of pain perception, that are not covered by the established indicators.

Ten-year survival and chipping rates and clinical quality grading of zirconia-based fixed dental prostheses.

OBJECTIVES: To prospectively evaluate the clinical long-term outcome of 3- to 6-unit fixed dental prostheses (FDPs) made of hot isostatic pressed (HIP) zirconia frameworks, veneered with a synthetic sintering glass-ceramic. MATERIALS AND METHODS: A total of 27 different restorations were cemented in 21 patients. FDPs were examined with regard to biological and technical complications/failures. Additionally, clinical quality was assessed based on (i) the California Dental Association (CDA) criteria, (ii) the patient's viewpoint according to Hickel, and (iii) periodontal parameters. Descriptive statistics were computed. The Kaplan-Meier estimator was used for the survival and chipping-free rates. Wilcoxon signed ranks test (ordinal/continuous data) or the McNemar test (binary data) was used to describe the periodontal outcome of abutment teeth versus that of the respective control teeth. RESULTS: After a mean observation period of 10.0 ± 2.1 years, the dataset comprised 15 patients with 20 (mainly posterior) FDPs. The 10-year survival rate and 10-year chipping-free rate were 95.0% (CI 86.0-100%) and 78.8% (CI 62.2-99.7%), respectively. Evaluation based on the CDA criteria yielded satisfactory (excellent or acceptable) results for all categories. This was also confirmed by the high level of patient satisfaction. The periodontal health of tissues adjacent to the study teeth was clinically acceptable, but inferior to the ones of control teeth. CONCLUSIONS: FDPs made from CAD/CAM-fabricated HIP zirconia ceramic frameworks have a favorable survival rate. However, because damage to the surface texture showed a disproportionate increase after long-term usage, additional long-term studies are required. CLINICAL RELEVANCE: The outstanding mechanical properties of zirconia-based systems have contributed to the belief that all-ceramics are a reliable material for prosthetic restorations. However, only long-term reports (such as this one) provide more detailed information on actual clinical efficacy.

Ten-year survival and complication rates of lithium-disilicate (Empress 2) tooth-supported crowns, implant-supported crowns, and fixed dental prostheses.

OBJECTIVES: To prospectively evaluate the clinical long-term outcome of tooth-supported crowns (SCs), implant-supported crowns (ISCs), and fixed dental prostheses (FDPs) made of a lithium-disilicate glass-ceramic framework material (IPS Empress 2). MATERIALS AND METHODS: Between 1997 and 1999, a total of 184 restorations (106 SCs, 32 ISCs, 33 FDPs, and 13 diverse restorations) were placed in 73 patients. Kaplan-Meier estimation was applied for survival and chipping-free rates. Inter-group comparison of both rates was realized by a log rank test and a 2×2 contingency table. Also, SCs and FDPs were compared regarding adhesive vs. conventional cementation, and anterior vs. posterior positioning, for impact on survival. RESULTS: Due to 14 dropouts (34 restorations) and reasonable exclusion of 19 other restorations, the final dataset included: i) 87 SCs [37 patients, mean observation time 11.4 (±3.8)years]; ii) 17 ISCs [12 patients, mean observation time 13.3 (±2.3)years; and iii) 27 FDPs [19 patients, mean observation time 8.9 (±5.4)years]. The 10-year survival rate/chipping-free rate for SCs were 86.1%/83.4%, for ISCs 93.8%/94.1%, and for FDPs were 51.9%/90.8%. Both ISCs and SCs had a significantly higher survival than FDPs (ISCs vs. FDPs: both tests p=0.001; SCs vs. FDPs: p=0.001 and p=0.005). Differences in the chipping-free rates did not reach significance. Also, neither the cementation mode nor positioning of the restoration had an impact on survival. CONCLUSIONS: SCs had a slightly lower outcome than can generally be expected from single crowns. In contrast, ICSs had a favorable outcome and the FDPs predominantly failed. CLINICAL SIGNIFICANCE: The practitioner's choice of dental materials is based (at best) on long-term experience. The present 10-year results are based on comprehensive data analyses and show the high potential of lithium-disilicate as a reliable material, especially for single-unit restoration.

SensInDenT-Noncontact Sensors Integrated Into Dental Treatment Units.

This paper presents the first system design (SensInDenT) for noncontact cardiorespiratory monitoring during dental treatment. The system is integrated into a dental treatment unit, and combines sensors based on electromagnetic, optical, and mechanical coupling at different sensor locations. The measurement principles and circuits are described and a system overview is presented. Furthermore, a first proof of concept is provided by taking measurements in healthy volunteers under laboratory conditions.