Head & Face Medicine最新文献

Background: This study aimed to compare the passivity, screw torque stability, and fracture resistance between dual- and screw-retained implant restorations, before and after thermomechanical loading.

Methods: Twenty metal-ceramic restorations were divided into two groups (n = 10 each). Group 1 (G1) featured dual-retained restorations on prefabricated titanium abutments, while Group 2 (G2) had screw-retained restorations on UCLA chromium-cobalt cast-to abutments. Passivity, adjustment ease, and torque loss were compared, along with fracture resistance and mode, post-fabrication and after thermomechanical loading (500 thermal and 500,000 mechanical loading cycles). Independent t-tests and Mann-Whitney U tests were used to compare passivity characteristics and fracture resistance, while torque losses were analyzed using a generalized estimating equations (GEE) model with LSD post-hoc test (α = 0.05).

Results: G1 required significantly less adjustment time and frequency (P < .001) and exhibited a lower torque angle (higher passivity) (P = .001) compared to G2. In G1, the screw torque loss (%) measured 24.02 ± 3.01 before and 36.51 ± 4.28 after loading compared to the initial torque and 16.17 ± 3.67 after loading compared to the detorque value. In G2, these values were 24.76 ± 3.45, 39.9 ± 2.55, and 20.1 ± 3.96, respectively. While the rate of torque loss did not differ significantly before loading, it was significantly higher in G2 after loading (P < .05). Fracture resistance was significantly higher in G1 (P < .05). Both groups exhibited a mixed type of failure mode.

Conclusions: Dual-retained metal-ceramic restorations outperformed screw-retained counterparts, demonstrating improved passivity, lower screw torque loss percentages, and higher fracture resistance.

Clinical trial number: Not applicable.

Introduction: With increasing life expectancy and physical activity, patients with dental implants face a growing lifetime risk of traumatic injury. In this context, the present study aimed to evaluate and compare the traumatic biomechanical effects between titanium and zirconia single dental implant in maxillary central incisor localization exposed to frontal maxillofacial trauma.

Materials and methods: In a 3D-FEA study design, maxillary models with titanium (model-A-IT) and zirconia (model-A-IZ) implants in region 21 and a bone model without dental implant (model-B) were subjected to a frontal traumatic load of 2000 N. The von Mises stress for all 3 models was measured at a predefined cortical peri-implant region of interest (ROI) and the stress values evaluated were compared between the models. Additionally, the maximum stress values within the implants were recorded and compared for the titanium and zirconia implants.

Results: The peri-implant cortical stress value/cortical fracture risk increased significantly for both implant models (model-A-IT, model-A-IZ) as compared to the implant-free bone model (model-A-IT/model-A-IZ vs. model-B; p < 0, 001); however, no difference between the two implant models evaluated (model-A-IT vs. model-A-IZ; P = 0.806) was seen. The stress values within the dental implants measured showed a higher maximum stress peak for the zirconia implant (IZ: 1137 MPa) than for titanium implant model (IT: 686.7 MPa).

Conclusion: When exposed to frontal trauma application both implant materials showed similar effects on cortical peri-implant bone; however, zirconia dental implants provide for a significantly higher maximum stress value within the implant than titanium implants representing a higher risk of fracture.

Objectives: To compare the postoperative complications, speech function, quality of life (QoL), overall clinical outcomes and flap volume loss of tongue reconstruction using anterolateral thigh (ALT) versus innervated-thoracodorsal artery perforator (iTDAP) flaps following hemiglossectomy for tongue squamous cell carcinoma (TSCC).

Materials and methods: Clinical data of 130 TSCC patients who underwent tongue reconstruction with ALT or iTDAP flaps were retrospectively analyzed. We compared two types of free flaps in terms of their characteristics and associated postoperative complications (including fistula, hematoma, infection, dehiscence and lower-limb venous thrombosis). Flap volume loss was assessed based on intraoperative and postoperative measurements. The University of Washington Quality of Life (UW-QOL) questionnaire, Speech Handicap Index (SHI) questionnaire and Vancouver Scar Scale (VSS) were used to evaluate quality of life (QoL), speech function and scar appearance at 3, 6 and 12 months postoperatively.

Results: The harvest time and length of the vascularized pedicle with vessels of a similar diameter were similar between the iTDAP and ALT groups (p > 0.05). Additionally, the postoperative complication rate and scar appearance were not significantly different between patients who underwent reconstruction with iTDAP flaps and those who underwent reconstruction with ALT flaps (p > 0.05). Notably, iTDAP flap recipients presented significantly improved QoL scores, higher SHI scores and shorter durations of bed rest (p < 0.05). Furthermore, flap volume loss was significantly lower in the iTDAP group compared with the ALT group (p < 0.05).

Conclusion: ITDAP flaps provide similar safety and complication rates as ALT flaps while offering better quality of life, improved speech function, shorter recovery times and lower flap volume loss, making them a viable alternative for functional tongue reconstruction.

Trial registration: The study was retrospectively registered at ClinicalTrials.gov (registration number: NCT06599801) on September 30, 2024.

Introduction: Our group has recently established the first ex vivo cadaveric models to simulate unilateral and bilateral cleft lip surgery. We have shown that these porcine snout disc models are suitable for novice cleft surgeons to understand the basic principles of cleft lip surgery and to practice the essential surgical steps. In this study we want to show that the ex vivo cleft lip models are not only suitable and helpful for residents, but also for students and experienced surgeons with and without experience in cleft surgery.

Methods: Three courses were held to evaluate the ex vivo cleft lip models: One for oral and maxillofacial surgeons from German cleft centers and two courses for dental students. All operated on the unilateral and bilateral ex vivo cleft lip models using the Millard technique. Questionnaires were used to assess their subjective opinion of the ex vivo cleft lip models. Tasks for the students were carried out to objectify their learning success. Three-dimensional scans were taken and analyzed using a previously validated intraoral scanner to objectively assess the outcome.

Results: The ex vivo cleft lip models are suitable for the training of students and experienced surgeons with varying levels of experience in cleft lip repair. Both models were rated as realistic in terms of tissue resemblance, surgical planning, and surgical management. In addition, the specialists rated the models as realistic overall. The models also provide students with several advantages, such as improved surgical skills and a better understanding of cleft surgery. Participants felt that the models should be made available not only to residents, but also to consultants and senior consultants and should be implicated in the dental curriculum.

Conclusion: The ex vivo cleft lip models made of porcine snout discs are suitable for a wide range of users starting from students to experienced surgeons to train in cleft lip surgery. The great advantage of these models is that experienced surgeons can work with an inexpensive and readily available model to improve their skills and modify their techniques.

Objective: Excessive intake of electrolyte sports drinks (ESDs) among adolescents and athletes is associated with dental erosion due to their low pH, while their sugar content increases the risk of dental caries. This study aimed to evaluate and compare the protective effects of incorporating either L-arginine or Salvadora persica (Miswak) extract into an ESD on enamel surface properties.

Materials and methods: Extracted human premolars were randomly assigned to three groups (n = 6): (1) plain ESD, (2) ESD with 1% L-arginine (Arg-ESD), and (3) ESD with 10% Salvadora persica extract (Mis-ESD). Each specimen was immersed in its respective solution for 5 min daily over 7 days. Post-treatment assessments included enamel microhardness (VHN), surface roughness (Sa), colour change (ΔE), Ca/P ratio, and scanning electron microscopy (SEM) for surface morphology. A taste acceptability survey was conducted in adult volunteers. Statistical analysis used one-way ANOVA (α = 0.05). In addition, a small panel of adult volunteers (n = 20) evaluated the taste acceptability of the modified formulations after providing informed consent.

Results: Both Arg-ESD and Mis-ESD significantly increased enamel microhardness and reduced surface roughness compared to plain ESD (P < 0.01), with Mis-ESD showing the greatest improvements. Mis-ESD also enhanced colour stability (P < 0.001). SEM images confirmed preservation of enamel structure, particularly in Mis-ESD specimens. Taste testing indicated good palatability for both modified formulations.

Conclusion: Incorporating Salvadora persica extract into ESDs significantly improved enamel resistance to erosion and enhanced aesthetic properties. Miswak-enriched ESDs could serve as a preventive option for dental erosion.

Clinical relevance: Formulating ESDs with Salvadora persica may reduce their erosive potential while preserving taste acceptability, offering a novel, consumer-friendly strategy to protect enamel in high-risk populations.

Objectives: This work aimed to investigate the impact of folic acid or multivitamin containing folic acid supplementation during pregnancy on morphology and mineral content of enamel structure in deciduous teeth.

Materials and methods: 54 exfoliating deciduous upper central incisors were extracted from children between the ages of 6 and 8. Teeth were divided according to the maternal use of micronutrients into three groups (n = 18), group I: no use; group II: folic acid; and group III: multivitamin containing folic acid. Specimens' ultrastructure was examined by scanning electron microscope (SEM). Elemental analysis was done using energy-dispersive X-ray spectroscopy (EDX), then statistical evaluation was conducted.

Results: SEM analysis revealed a uniform enamel surface morphology, indicating a level of resistance to normal physiological enamel wear in groups II and III in contrast to group I. These findings were affirmed by EDX assessment where enamel surface revealed statistically significant higher values for calcium, and phosphorus in groups II and III relative to group I. Additionally, carbon content revealed statistically significant higher values in group I than those of groups II and III, suggesting more susceptibility of hydroxyapatite crystals to dissolution in group Ι.

Conclusion: Maternal micronutrients supplementation was linked with the preservation of enamel structure in primary teeth. This indicates enhanced enamel resistance to mineral loss during normal physiological dental wear. The findings of this preliminary study highlighted the importance of prenatal multivitamin supplementation as a strategy in preventive dentistry.

Study design: We conducted a prospective cohort study comparing interobserver reliability of 2 different 3D scanning measurement methods following dermal filler therapy in oral cleft patients.

Objective of the study: The objective of the study was to compare the interobserver reliability of 2 different assessment methods of 3D facial scan data.

Methods: We studied 10 oral-cleft patients prospectively who underwent dermal filler therapy in the oral region by a single oral-surgeon using a modified injecting technique with 27 gauge 25 mm micro-cannula between 2021 and 2023. 3D facial scans were made before the treatment procedure and during follow-up visits and were used for analysis. The interbody fusion was scored on these 3D images using the 2 classification systems (Method 1, Method 2) by 3 experienced orthodontic specialists all of whom were blinded to clinical data and outcome.

Results: Of the 2 classifications included in the current study, all classifications had a high interobserver agreement.

Conclusion: The 2 assessment methods used in this study showed high interobserver reliability so we can conclude that, the applied methods may provide as a validation in the outcome of dermal filler therapy. However, we suggest that further refinements may be required to achieve a reliable and consistent assessment of 3D facial scan analysis after dermal filler therapy in oral cleft patients.

Background: To develop a deep learning-based model that is capable of automatically segmenting teeth in cone-beam computed tomography (CBCT) images and generating auxiliary diagnostic reports.

Methods: A two-stage pipeline model comprising a segmentation module and a classification module was designed. The segmentation module integrates the 3D TransUNet model and fine-tuned nnU-Netv2 framework to predict tooth location and numbering. The classification module uses a 3D DenseNet169 model to assess tooth conditions and detect dental diseases. A total of 450 CBCT datasets were collected, preprocessed, and annotated with tooth contours, numbering, and disease status. The dataset was randomly split into training, validation, and test sets at a 3:1:1 ratio. The model's performance was then evaluated by using multiple quantitative metrics.

Results: The segmentation module achieved a Dice similarity coefficient (DSC) of 0.9409 and an average symmetric surface distance (ASSD) of 0.5011. The classification module, which is based on the 3D DenseNet169 model, achieved an accuracy of 0.9297 and an F1-score of 0.9252.

Conclusions: The two-stage pipeline model effectively integrates automated tooth segmentation and auxiliary diagnosis. The segmentation module demonstrates high accuracy, while the classification module exhibits strong diagnostic performance. The final output seamlessly combines segmentation and the diagnostic results, enabling the automated generation of structured auxiliary diagnostic reports with tooth numbering. By significantly enhancing the diagnostic efficiency, the proposed method offers substantial support for clinical decision-making in dentistry and holds great potential for real-world applications.

Background: One component of facial aesthetics is a harmonic facial profile. Orthodontic treatment and/or orthognathic surgery can affect the facial profile by influencing the underlying hard-tissue structure. The aim of this study was to improve the prediction of treatment outcomes by evaluating 3D perioral frontal and buccal soft-tissue changes after protrusion of incisors in ten young adults.

Methods: The participants had neutral occlusion and physiologic incisor inclination. 3D-printed acrylic veneers with thicknesses of 1-4 mm were bonded to the labial surfaces of the upper and lower incisors. 3D face scans with and without veneers were taken to evaluate perioral soft tissue changes using 44 landmarks. Face scans were superimposed at the forehead. Soft-tissue changes were evaluated using linear mixed-effects models.

Results: Interrelations between simulated incisor protrusion and the resulting soft-tissue changes were statistically highly significant (p < 0.005) and nearly linear. Simulated isolated upper incisor protrusion caused greatest forward positioning of the labrale superius convex [LS-con] landmark-by 0.65 mm per millimetre of veneer thickness. Lower lip displacement at the labrale inferius convex [LI-con] landmark was greatest when both upper and lower incisors were protruded (0.76 mm/mm). The vertical lip displacement rate for simulated upper and lower incisor protrusion was 0.12 mm/mm upward positioning of LS-con and 0.66 mm/mm downward positioning of LI-con. Mixed-effects models revealed that a 1-mm increase in initial lip thickness at the labrale superius reduces soft-tissue displacement by about 8% of the simulated tooth movement.

Conclusions: Anterior positioning of incisors leads to predictable, direction-specific changes in perioral soft tissues. The magnitude and pattern of soft-tissue responses vary with the combination of upper and lower incisor movement and individual lip thickness. These findings may support clinical planning in orthodontic and/or orthognathic treatments.