Elements of morphology: Standard terminology for the teeth and classifying genetic dental disorders.

Dental anomalies occur frequently in a number of genetic disorders and act as major signs in diagnosing these disorders. We present definitions of the most common dental signs and propose a classification usable as a diagnostic tool by dentists, clinical geneticists, and other health care providers. The definitions are part of the series Elements of Morphology and have been established after careful discussions within an international group of experienced dentists and geneticists. The classification system was elaborated in the French collaborative network "TÊTECOU" and the affiliated O-Rares reference/competence centers. The classification includes isolated and syndromic disorders with oral and dental anomalies, to which causative genes and main extraoral signs and symptoms are added. A systematic literature analysis yielded 408 entities of which a causal gene has been identified in 79%. We classified dental disorders in eight groups: dental agenesis, supernumerary teeth, dental size and/or shape, enamel, dentin, dental eruption, periodontal and gingival, and tumor-like anomalies. We aim the classification to act as a shared reference for clinical and epidemiological studies. We welcome critical evaluations of the definitions and classification and will regularly update the classification for newly recognized conditions.

Translation and validation of the French version of the Child Perceptions Questionnaire for children aged from 8 to 10 years old (CPQ 8-10).

BACKGROUND: The Child Perceptions Questionnaire (CPQ) belongs to a set of questionnaires measuring Child Oral Health Quality of Life (COHQOL). The CPQ is used to collect the perceptions of children on the impact of oral diseases on their quality of life. This cross-sectional study was aimed to translate the CPQ8-10 into French language and evaluate its psychometric properties. METHODS: The translation process complied with international recommendations. The final French version was tested on children aged 8-10 years old attending consultations in a Parisian public hospital and divided into three groups: children with oral-facial clefts, children with dental anomalies linked to a rare disease other than clefts and children presumed to be healthy and without anomalies. The internal consistency relating to the reliability of CPQ8-10 was evaluated by Cronbach's alpha. The intra-class correlation was used to measure reproducibility at the test-retest level. Construct validity was evaluated by Spearman's correlation and tested using factor analysis. The discriminant validity was assessed using Kruskall Wallis test. Criterion validity was calculated using Spearman's correlation. RESULTS: One hundred seventy-six children participated in this study. During the translation process, minor changes were made. The French version showed good reliability with a Cronbach's alpha of 0.81 for the total scale. The ICC of the test-retest was excellent (=0.90) demonstrating good reproducibility. The construct validity was acceptable with a statistically significant correlation between the scores of the French-CPQ8-10 and the evaluation of oral health (r = 0. 381 and p < 0.001) and its impact on oral health quality of life (r = 0.363 and p < 0.001). The loading weights obtained in the Exploratory Factor Analysis showed that this model revealed seven factors with eigenvalue greater than 1, explaining the 63,89% of the cumulative variance. The differences observed between the scores of the study groups revealed good discriminant validity. Criterion validity was supported by significant association between CPQ scores and pain. CONCLUSION: The French-CPQ8-10 is reliable and valid for use with the children of this age group.

Parental-Caregivers Perceptions Questionnaire (P-CPQ): translation and evaluation of psychometric properties of the French version of the questionnaire.

BACKGROUND: The Parental-Caregivers Perceptions Questionnaire (P-CPQ) is a measure of parental/caregivers' perceptions of the impact of children's oral health on quality of life. The aim of the study was evaluate the psychometric properties of the French version of the P-CPQ. METHOD: The original P-CPQ was developed in English language and has 31 items divided into four sub-scales. This cross-sectional study used the translation-back translation method. The translated questionnaire was pretested on 14 parents-caregivers to obtain the final French version. The psychometric properties were tested on 142 parents/caregivers of three clinical groups of children from 8 to 10 years old without dental/facial anomalies (presumed healthy), with oral-facial clefts and with oral-dental anomalies linked to a rare disease other than cleft, approached in the waiting room of the Centre of the Hospital Rothschild in Paris, France, where the children attended treatment. Internal consistency was assessed by Cronbach's alpha and test-retest reliability by Intra-class Correlation Coefficient (ICC). Construct validity was measured by correlations between the total scores and the global ratings of oral health and overall wellbeing, and tested using exploratory factor analysis (EFA) and the factorial structure was evaluated by the partial confirmatory factor analysis (PCFA). Discriminant validity was determined using Kruskall-Wallis test. RESULTS: The mean (standard deviation) P-CPQ score was 18.73(18.79). Internal consistency was confirmed by a Cronbach alpha of 0.85. The test-retest reliability revealed that the responses to items were satisfactorily stable (ICC = 0.88). Construct validity was demonstrated by significant correlation coefficients between the total scale and the global ratings (r = 0.54 and 0.46; p < 0.001). Factor analysis with Principal Component Analysis extracted seven factors explaining 65.23% cumulative variance. Goodness-of-fit indices for partial confirmatory factor analysis were satisfactory for the 7-factors model of the French-PCPQ version. There were statistically significant differences between clinical groups regarding the total scale, thus demonstrating discriminant validity (p < 0.001). CONCLUSION: This French P-CPQ version showed reliability and validity comparable to the previous versions. However, the cross-cultural structure of the subscales should be further evaluated.

Students' perceptions of knowledge reinforcement on indirect prosthetic dental material choices by a translational approach.

PURPOSE/OBJECTIVES: The aim of this study is to evaluate students' perceptions of the reinforcement of knowledge via innovative, case-based, hands-on learning regarding indirect prosthetic material choice. METHODS: Six different clinical cases that represented common prosthetics were used in this simulation training. In each case, clinical pictures were associated with three-dimensional (3D)-printed replicates of final restorations and PolyJet polychromatic models with the goal of enabling students to deliberate and exchange ideas in small groups. After a debriefing session regarding the therapeutic potentialities of the first three cases alongside teachers, a lecture concerning prosthetic material choices was provided, and a zirconia crown was stained by each student to enable them to obtain a better understanding of the dental technician profession. Finally, the latter three cases were studied and analyzed in the same manner. The students' perceived reinforcement of knowledge was recorded before and 1 month after the hands-on simulation training experience, and their satisfaction was evaluated immediately thereafter on Likert scales. Students' perceived reinforcement of knowledge was subjected to statistical evaluation. RESULTS: A high level of overall satisfaction was observed (4.60). All of the items pertaining to students' satisfaction received scores >3. One month after this hands-on approach, students' confidence in their ability to choose a material on the basis of its mechanical, optical, and luting properties increased significantly (from 2.58 to 3.64; from 2.83 to 3.64; and from 2.72 to 3.58, respectively) (p < 0.05). CONCLUSIONS: This innovative, hands-on approach had a significant positive effect on students' perceived reinforcement of knowledge.

Implementation of game-based training in oral rehabilitation of edentulous patients in an undergraduate dental course.

BACKGROUND: Coronavirus disease-19 dramatically changed the learning conditions of dental students, with restricted access to training sessions and clinical practice. The "Playdent" project proposed the integration of serious games (SGs) in the third-year curriculum, based on tailor-made scenarios questioning the first dental visit of edentulous patients, and examined whether training with the games would advance students' learning outcomes. MATERIALS AND METHODS: Test scores of 89 students, allocated either to a "test" group that accessed SGs during a 4-week test period in addition to conventional lectures or to a "control" group that benefited solely from conventional lectures, were measured before and immediately after the test period. The subsequent satisfaction of students was assessed in the "test" group. RESULTS: Scores obtained after the 4-week period significantly increased within the "test" group (11.1% ± 24.9%, p = 0.04, degree of freedom [df] = 30) while they did not change within the "control" group (p = 0.21, df = 57). Qualitative feedback expressed by students who played SGs during the 4-week period demonstrated that 71% of them rated the SGs as satisfactory and 91% of them judged the consistency of SGs content with lectures to be satisfactory. CONCLUSION: Game-based learning showed a positive impact on the learning outcomes of third-year students. Qualitative assessments provide insights into the pertinence of SGs offered in addition to traditional lectures of third-year complete denture courses. SGs may consolidate skills in oral rehabilitation acquired through traditional passive learning formats proposed in preclinical courses.

Revisiting the effects of low-concentration hydrogen in NiTi self-expandable stents.

Superelastic NiTi is widely used in self-expandable transcatheter devices such as cardiovascular stent, neuro thrombectomy retriever and aortic valve scaffold. Hydrogen at a concentration of CH < 100 wppm is almost always contained in these devices due to the chemical surface treatments during production. The survey of hydrogen concentrations in 9 commercial stent samples show H concentrations values ranging from 6 to 55 wppm. Correspondingly, hydrogen (8 wppm and 40 wppm) is charged to NiTi samples at two thermal-treatment states (500 °C-annealed and 800 °C-annealed) for comparative studies. The effects of hydrogen are revisited to clarify the hydrogen-induced changes of the operating deformation mechanism and the subsequent reduction of ductility in NiTi of both states. In-situ investigations at mesoscopic length scale (50-500 µm) are performed using electron backscatter diffraction (EBSD) mapping during tensile deformation of the 800 °C-annealed samples. The deformation microstructure and the operating deformation mechanism are further studied at microscopic length scale (<5 µm) by transmission electron microscopy (TEM) for both 500 °C and 800 °C annealed samples. The results display that the influence of 8 wppm H on final material properties is insignificant in 500 °C and 800 °C annealed samples. However, for both, a concentration of 40 wppm H noticeably decreases the martensitic transformation temperature and the macroscopic ductility of the samples. In the 800 °C-annealed sample, in-situ EBSD observes that the propagation of martensite band (MB) has finished at ε = 0.1 in the 8 wppm H sample while the propagation seems interrupted in the 40 wppm H sample until the same strain. Inside and surrounding the MB, island-like non-transformed austenite zones are formed representing 14.8area% of the observation zone. In both 500 °C and 800 °C annealed samples, TEM observations found extensive dislocation activity in specific regions of the samples after being charged to 40 wppm hydrogen. Thermal desorption spectroscopy (TDS) confirms that a hydrogen redistribution has happened in the 40 wppm hydrogen during the homogenization process. The change of local operating deformation mechanism from martensitic transformation to dislocation slip is thought to be responsible to the changes of mechanical properties of hydrogen-charged NiTi. The effect is further discussed in relation to the redistribution of hydrogen due to trapping at structural defects. In general, the results suggest that the influence of 8 wppm hydrogen is insignificant on the mechanical properties of NiTi, whereas the NiTi containing 40 wppm hydrogen may present risks of hydrogen-related mechanical failure within the strain amplitude range of a stent crimping process.

Influence of polymerization pressure and post-cure treatment on conversion degree and viscoelastic properties of polymer infiltrated ceramic network.

This study aimed at determining an optimum polymerization pressure for Polymer Infiltrated Ceramic Network (PICN) blocks by characterizing the conversion degree (DC) and the viscoelastic properties of experimental PICN blocks polymerized at 90 °C under various high pressures followed or not by post-cure treatment (PC). Near infrared analysis and dynamic mechanical analysis were used to characterize DC and viscoelastic properties of sixteen PICN: one control (thermo-cured) and fifteen experimental groups (one thermo-cured followed by PC and fourteen high pressure polymerized PICN, in the range of 50-350 MPa without and with PC). Conversion degree of high pressure polymerized PICN blocks without post curing displays an optimum between 100 and 150 MPa resulting in an improved E' and Tg. Post curing induces a higher DC with a controversial effect on thermomechanical properties. The results suggested that 100-150 MPa without PC is an optimum polymerization parameter, resulting in PICN blocks with significantly better DC, Tg, E'.

On the High Sensitivity of Corrosion Resistance of NiTi Stents with Respect to Inclusions: An Experimental Evidence.

In this study, the electrochemical breakdown potentials (E b) of NiTi stents were assessed in correlation to their nonmetallic inclusion fractions in the extra low inclusion (ELI) range (inclu.% < 1% in area fraction, average size <39 µm). Quantitative investigations were performed to study the role of nonmetallic inclusions during pitting corrosion. Two stent samples with different inclusion fractions were fabricated using commercial NiTi tubes for studying the corrosion and mechanism. A survey of seven commercial stents in Europe was also conducted. Dependence was observed between the breakdown potentials and the inclusion fractions in the ELI stent (inclu.% = 0.2-0.8%), in which the breakdown potentials were found to be inversely proportional to inclusion fractions and densities (E b dropped from ∼800 to ∼400 mV). No breakdown occurred on the samples using high-purity NiTi materials (inclu.% < 0.1%). The roles of inclusions in pitting mechanisms were investigated using scanning electron microscopy (SEM) characterizations. The microstructural evidence showed that the impact of TiC and Ti2NiO x was very different in the pitting process. A maximum inclu.% ≤ 0.9% was required for obtaining E b ≥ 600 mV to meet the Food and Drug Administrations (FDA's) in vivo safety acceptance (low risk up to 6 months postimplantation). The high-purity stents (inclu.% < 0.1%) did not exhibit corrosion susceptibility until 1000 mV, suggesting superior corrosion resistance and thus long-term in vivo safety.

Axial displacement of abutments into implants and implant replicas, with the tapered cone-screw internal connection, as a function of tightening torque.

PURPOSE: The passive fit of a superstructure on implant abutments is essential to success. One source of error when using a tapered cone-screw internal connection may be the difference between the tightening torque level applied to the abutments by the laboratory technician compared to that applied by the treating clinician. The purpose of this study was to measure the axial displacement of tapered cone-screw abutments into implants and their replicas as a function of the tightening torque level. MATERIALS AND METHODS: Twenty tapered cone-screw abutments were selected. Two groups were created: 10 abutments were secured into 10 implants, and 10 abutments were secured into 10 corresponding implant replicas. Each abutment was tightened in increasing increments of 5 Ncm, from 0 Ncm to 45 Ncm, with a torque controller. The length of each sample was measured repeatedly with an Electronic Digital Micrometer. The mean axial displacement for the implant group and the replica group was calculated. The data were analyzed by the Mann-Whitney and Spearman tests. RESULTS: For both groups, there was always an axial displacement of the abutment upon each incremental application of torque. The mean axial displacement values varied between 7 and 12 microm for the implant group and between 6 and 21 microm for the replica group at each 5-Ncm increment. From 0 to 45 Ncm, the total mean axial displacement values were 89 microm for the implant group and 122 microm for the replica group. CONCLUSION: There was a continuous axial displacement of the abutments into implants and implant replicas when the applied torque was raised from 0 to 45 Ncm. Torque applied above the level recommended by the manufacturer increased the difference in displacement between the two groups.

[Orthodontic management of obstructive sleep-disordered respiratory disorders]. / Prise en charge orthodontique des troubles respiratoires obstructifs du sommeil de l'enfant.

Through his/her knowledge of cranio-facial growth, the orthodontist plays a leading role within the multidisciplinary team that tracks and treats sleep-disordered breathing (SDB) in children. Correction of craniofacial risk factors (maxillary deficiency and retrognathia) is commonly used by practitioners alongside orthodontic treatment such as OMA and RME in the optimal conditions afforded by childhood growth. Myofunctional therapies are performed to restore correct stomatognathic function and play a central role in the management of SDB in children. The orthodontist is therefore a key player in the medical treatment chain of these children.

Translation and cross-cultural validation of the French version of the Sleep-Related Breathing Disorder scale of the Pediatric Sleep Questionnaire.

BACKGROUND: Sleep-disordered breathing (SDB), including obstructive sleep apnea syndrome, is often underestimated because it requires a burdensome test (ie, polysomnography) to ensure diagnosis. To improve polysomnography referral, it is of utmost importance to validate efficient alternative screening tools. This study aimed to provide a translation and a cross-cultural validation of the Pediatric Sleep Questionnaire (PSQ) into French to obtain an easy-to-use and reliable screening tool. The psychometric properties of the French version were also determined. METHODS: The process of cross-cultural adaptation was carried out following these steps: forward-backward translation, evaluation by an expert committee, and pretesting of the pre-final version. Reliability of the French-PSQ version was assessed by Cronbach's alpha coefficients and Spearman's correlation on a convenient sample of 201 children (aged between 2 and 17 years). Construct validity was determined by factor analysis of principal components. RESULTS: Internal consistency was within an adequate range for all subscales: 0.711 for snoring, 0.559 for sleepiness, 0.682 for behavioral problems, and 0.776 for the whole questionnaire. Spearman's correlation analysis comparing questionnaires administered two weeks apart showed good correlation coefficients for all subscales (snoring: 0.642, sleepiness: 0.846, behavioral problems: 0.780, and entire SRBD scale: 0.835). Factor analysis performed to assess the structure of the French-SRBD scale confirmed the same four factors described in the original questionnaire ("breathing," "behavior," "sleepiness," and "other"). CONCLUSION: The French version of the PSQ has been successfully cross-culturally adapted and showed good psychometric properties, suggesting that it is useful as a tool to screen sleep-disordered breathing in French-speaking children.

Characterization of hydroxyapatite films obtained by pulsed-laser deposition on Ti and Ti-6AL-4v substrates.

OBJECTIVES: Pulsed-laser deposition (PLD) is a development process to obtain hydroxyapatite (HA) thin film. It is an alternative to hydroxyapatite deposition techniques usually employed to cover orthopaedic or dental titanium implant surfaces. The aim of this study is to find out the characteristic ratio for Ca/P (1.66) deposit on titanium implant with the PLD process. METHODS: In a preliminary study, the coating parameters of pure and highly crystalline HA on Ti or Ti-6Al-4V substrates were verified by analysing the deposit by Rutherford backscattering spectroscopy (RBS). Ablation parameters to reach a stoichiometric hydroxyapatite composition (ideal Ca/P atomic ratio) and to control the growth of crystalline phases were: 575 degrees C for the substrate temperature, 0.4 mbar H2O vapour pressure in the ablation chamber, the target substrate distance was 40 mm and the deposition time was 120 min. In a second part, the film properties were analysed by means of XRD, SEM, AFM. The coating adhesion of the HA to the substrate was determined with a micro scratch tester. RESULTS: The analysed HA thin films showed a perfect crystallized and textured deposit. Sample observation and surface quality analysis demonstrated a surface roughness and adhesion of the films to the substrates compatible with biological applications. SIGNIFICANCE: These results suggest that pulsed-laser deposition is a suitable technique to obtain crystalline and adherent hydroxyapatite films on Ti or Ti-6Al-4V substrates. The quality of the HA deposit with the PLD process could be an interesting option for coating dental implant.

Fatigue and mechanical properties of nickel-titanium endodontic instruments.

Shape memory alloys are increasingly used in superelastic conditions under complex cyclic deformation situations. In these applications, it is very difficult to predict the service life based on the theoretical law. In the present work, fatigue properties of NiTi engine-driven rotary files have been characterized by using differential scanning calorimetry (DSC) and mechanical testing (bending). The DSC technique was used to measure precise transformation. The degree of deformation by bending was studied with combined DSC and mechanical property measurements. In these cold-worked files, the high dislocation density influences the reorientation processes and the crack growth. Some thermal treatments are involved in promoting some changes in the mechanical properties and transformation characteristics. Annealing around 400 degrees C shows good results; the recovery allows a compromise between an adequate density for the R-Phase germination and a low density to limit the brittleness of these instruments. In clinical usage, it is important to consider different canal shapes. It could be proposed that only few cycles of use is safe for very curved canals but to follow the manufacturer's advise for straight canals.

Stiffness in bending of a superelastic Ni-Ti orthodontic wire as a function of cross-sectional dimension.

Superelasticity is a property used in orthodontics to initiate tooth movement in the first stage of orthodontic treatment. It is the aim of all clinicians to accomplish biological tooth movement, which implies the use of low, continuous force and requires archwire with low stiffness. In this study, 15 nickel-titanium archwires with three different cross-sectional dimensions were tested in three-point bending to determine the nature of forces in a loading and unloading cycle. The evolution of stiffness in bending as a function of wire size is discussed. The applied forces or stiffness dependence on cross-sectional size differs from the linear-elastic prediction because of the superelasticity property. We discuss the origin of the nonconventional profile of curves and the nature of reversible large deformation of these alloys. Martensitic transformation is at the origin of nonlinear elasticity. The stiffness decreases with increasing deflection, and this phenomenon is emphasized in the unloading process. The value of stiffness appears to vary with wire size but depends on the ratio of volume of martensitic transformation. During martensitic transformation, the rigidity (elastic modulus) of the alloy is nonconstant. These results and their understanding should allow a different approach of biomechanical considerations, ie, a large-size square wire does not produce necessarily high forces.

Evolution of flexural rigidity according to the cross-sectional dimension of a superelastic nickel titanium orthodontic wire.

The choice of the most suitable orthodontic wire for each stage of treatment requires estimation of the forces generated. In theory, the selection of wire sequences should initially utilize a lower flexural rigidity; thus clinicians use smaller round cross-sectional dimension wires to generate lighter forces during the preliminary alignment stage. This assessment is true for conventional alloys, but not necessarily for superelastic nickel titanium (NiTi). In this case, the flexural rigidity dependence on cross-sectional dimension differs from the linear elasticity prediction because of the martensitic transformation process. It decreases with increasing deflection and this phenomenon is accentuated in the unloading process. This behaviour should lead us to consider differently the biomechanical approach to orthodontic treatment. The present study compared bending in 10 archwires made from NiTi orthodontics alloy of two cross-sectional dimensions. The results were based on microstructural and mechanical investigations. With conventional alloys, the flexural rigidity was constant for each wire and increased largely with the cross-sectional dimension for the same strain. With NiTi alloys, the flexural rigidity is not constant and the influence of size was not as important as it should be. This result can be explained by the non-constant elastic modulus during the martensite transformation process. Thus, in some cases, treatment can begin with full-size (rectangular) wires that nearly fill the bracket slot with a force application deemed to be physiologically desirable for tooth movement and compatible with patient comfort.