Head & Face Medicine最新文献

Background: Tissues can adhere to cold metal surfaces, causing tissue damage upon detachment. For children, this often involves the tongue, so-called tundra tongue. This study aimed to assess the risk and extent of tongue tissue damage following adhesion to cold metal lamp posts.

Methods: Eighty-four porcine tongues were acquired shortly after slaughter. The apex and basis of each tongue were separately brought into contact with a section of a cold metal lamp post and detached gradually or rapidly. Detachment force was recorded and tongues were visually inspected for macroscopic injuries. Selected tongues were assessed histologically. Finite element simulations were conducted in COMSOL Multiphysics to model intra-tissue temperature over time. Each tongue was tested twice (apex and basis), resulting in 168 experiments. Four experiments were excluded, leaving 164 for analysis.

Results: Avulsion injury occurred in 89 of 164 experiments (54%) with risk increasing with the detachment force (p < 0.001). Peak tongue detachment force was associated with contact time (p < 0.001), tongue region (apex versus basis, p < 0.01), and release type (rapid versus gradual, p < 0.001). A non-linear relationship was found between metal temperature and detachment force (p < 0.01), with peak adherence at approximately -7.5 °C. Histological evaluation demonstrated intra-epidermal damage that could be rationalized with computer modelling. Nearly all experiments (92%) caused macroscopic, but not microscopic, cold injury, with risk increasing at lower metal temperatures. Computer simulations suggest that tissue damage is related to superficial tissue freezing that occurs under typical winter conditions and short exposure times.

Conclusions: The tundra tongue is a complex phenomenon. Although the risk of avulsion injury is significant, our findings indicate limited damage potential under normal winter conditions and brief exposure times.

Background: This study aimed to investigate the feasibility and efficacy of 3D-printed nasal models for training in nasal endoscopic examination and artificial lacrimal duct intubation, while also evaluating trainees' learning experience and skill improvement.

Methods: A nasal model replicating anatomical structures was constructed using stereolithography (SLA) 3D printing based on adult nasal CT data. Twenty-four ophthalmologists subsequently underwent training involving simulated nasal endoscopic procedures and artificial lacrimal duct intubation on these models. Pre- and post-training practical assessments included the anatomical identification rate, nasal endoscopic operation time, and the success rate of artificial lacrimal duct intubation. A 5-point Likert scale questionnaire was used to measure participants' learning outcomes and satisfaction.

Results: 3D-printed model accurately replicated nasal anatomical details, encompassing the nasal cavity, nasopharyngeal structures, and precise nasolacrimal duct opening localization. Following training, participants demonstrated significantly improved anatomical identification rates (p < 0.0001) and substantially reduced endoscopic operation times (p < 0.001), further achieving a 95.8% (23/24) qualification rate for lacrimal duct implantation positioning. Notably, questionnaire feedback indicated that 91.7% of trainees agreed the model enhanced anatomical understanding; 87.5% affirmed its haptic feedback approximated real surgery; 95.8% reported increased surgical confidence; and 91.7% endorsed its use for pre-operative training.

Conclusions: 3D-printed nasal model offers a high-fidelity, reusable platform for nasal endoscopy and lacrimal surgery training, effectively advancing trainees' operative skills and confidence-thus demonstrating significant potential for clinical dissemination.

Objective: Mucopolysaccharidoses (MPS) represent a heterogeneous group of rare, inherited lysosomal storage disorders characterized by the accumulation of glycosaminoglycans in various tissues, including the orofacial region. This study aims to investigate the orofacial features and radiographic manifestations in a cohort of pediatric patients diagnosed with MPS.

Materials and methods: Thirty-five patients (18 males, 17 females) diagnosed with different subtypes of MPS underwent comprehensive oral and radiographic examinations. The presence and frequency of clinical and radiographic findings were documented. Radiographic analysis was feasible in 26 patients, with 9 excluded due to severe intellectual disability. The decayed, missing, and filled teeth (DMFT/dft); decayed, missing, and filled surfaces (DMFS/dfs) indices were recorded according to WHO criteria. The dental plaque scores were determined according to Silness & Löe plaque index. Data was analysed using SPSS 25.0, with descriptive statistics summarizing variables and Fisher's Exact test applied for subgroup comparisons by MPS subtype; significance was set at p < 0.05.

Results: The most frequent orofacial findings included tongue thrusting (80%, n = 28/35), limited mouth opening (71%, n = 25/35), macroglossia (71%, n = 25/35), and anterior open bite (54%, n = 19/35). Radiographic analysis revealed a thin mandibular cortex in 38% (n = 10/26) of cases, impacted teeth in 27% (n = 7/26), and a short mandibular ramus in 23% (n = 6/26). This is the first reported case of a talon cusp, a rare dental anomaly occurring in a patient with MPS-IV, highlighting a previously unrecognized association in the literature. The distribution of MPS types was: MPS-I (n = 3), MPS-II (n = 6), MPS-III (n = 8), MPS-IV (n = 10), MPS-VI (n = 7), and MPS-VII (n = 1).

Conclusions: Orofacial manifestations are frequently observed in patients with MPS and may serve as early indicators of the disorder, particularly within dental settings. Recognition of these features is essential, as they underscore the need for multidisciplinary care and routine dental evaluations to mitigate potential complications and enhance overall quality of life.

Clinical relevance: Orofacial abnormalities are common in children with MPS and may provide early clues to the diagnosis. This study emphasizes the importance of dental evaluations in identifying these signs, including the first reported case of a talon cusp in a patient with MPS. Early recognition by dental professionals can support timely diagnosis, guide appropriate referrals, and improve patient outcomes through coordinated, multidisciplinary care.

Objective: This study aimed to assess the diagnostic value of electrocochleography (ECochG) for identifying endolymphatic hydrops (EH) and to investigate whether integrating multimodal auditory data from ECochG and pure-tone audiometry (PTA) into machine learning models could improve diagnostic accuracy and clinical interpretability.

Methods: A prospective cohort of 78 patients (156 ears) with a strong clinical suspicion of EH was evaluated between March and June 2024. ECochG and PTA examinations were performed, and extracted parameters were used to develop and validate multiple machine learning models. Diagnostic performance was compared using the area under the receiver operating characteristic curve (AUC), sensitivity, specificity, and overall accuracy.

Results: After excluding six ears with unrecordable ECochG data, 150 ears were analyzed. Models based solely on ECochG-derived features demonstrated limited diagnostic performance (maximum AUC = 0.61). When multimodal hearing data were incorporated, model performance improved substantially. The Light Gradient Boosting Machine (LightGBM) model achieved an AUC of 0.92 and an accuracy of 0.73 for predicting the anatomical distribution of EH.

Conclusions: Integrating multimodal auditory data into interpretable machine learning models can markedly improve the diagnostic accuracy of endolymphatic hydrops, providing an objective framework to support early clinical diagnosis and management. However, this study is limited by a small sample size and has not yet been validated across multiple centers.

Level of evidence: Level 3.

Purpose of the study: This study demonstrates and investigates the feasibility of a novel approach for dental rehabilitation in complex maxillary and midfacial defects, often resulting in severe pseudo-class III relationships. It explores the use of patient-specific subperiosteal implants (IPS Implants^® Preprosthetic) with innovative design variations that anchor to the skull base from below and laterally, extending beyond traditional implants to provide enhanced stability in cases of significant bone loss.

Methods: Patients with significant maxillary and midfacial bone loss due to postablative defects were included in our case series, with or without irradiation. From 100 patients, 13 required design modifications based on FEM analysis, involving implant anchorage to the lateral skull base and/or pterygoid process. Eight patients received single-sided lateral skull base extensions; one posttraumatic case required bilateral extensions. In five of 13 cases, additional extensions to the pterygoid process were implemented. One case needed both bilateral skull base and pterygoid extensions, while two had bilateral pterygoid and a single-sided skull base extension. Outcomes assessed included primary stability, prosthodontic restoration, complications, and soft tissue management.

Results: No implant failures occurred during follow-up, with functional stability established immediately post-insertion. Prosthodontic restoration succeeded in all cases, with no stability loss or periimplantitis. Mucositis was noted around posterior posts in some instances, and one bar required trimming due to soft tissue changes, without affecting implant function. One implant had to be removed, due to chronic pain.

Conclusions: Patient-specific IPS Implants^® Preprosthetic with design extensions provide a biologically suitable solution for stable dental rehabilitation in severe maxillary and midfacial structure loss, without biomechanical limitations. Achieving rigid fixation distant from the soft tissue transition is crucial for success.

Background: This study aims to evaluate the impact of different angular orientations and buccolingual positions of impacted third molars on the incidence of bad splits during sagittal split ramus osteotomy using finite element analysis.

Materials and methods: A total of 12 mandibular models were constructed, each representing a unique combination of third molar orientations (vertical, distoangular, horizontal, mesioangular) and positions (buccal, lingual, central). A force of 20 N was applied from the osteotomy line toward the proximal and distal segments to simulate the working principle of the Smith Spreader instrument.

Results: The maximum principal stress followed the order: vertical > distoangular > horizontal > mesioangular. In terms of positional stress distribution, the buccal position generated the highest stress, followed by lingual and central positions. Similar trends were observed across all stress criteria evaluated.

Conclusion: The orientation and position of impacted third molars have a direct effect on the risk of bad splits during SSRO. Mesioangular and centrally positioned teeth were associated with lower stress levels, indicating lower risk, while vertically oriented and buccally or lingually positioned molars showed significantly higher stress concentrations. Thus, extraction of high-risk impacted third molars prior to surgery is recommended to reduce the likelihood of complications.

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.