Head & Face Medicine最新文献

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.

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.