Neutral zone recording in computer-guided implant prosthesis: A new digital neuromuscular approach

Factors Related to Masticatory Rhythm in Patients with Oral Tumors

Background: Older adults who have undergone surgery for oral tumors are at increased risk of impaired masticatory rhythm. This study investigated the correlations between masticatory rhythm, objective masticatory performance, and subjective masticatory performance as well as factors related to masticatory rhythm. Methods: The participants were 44 adults (24 men, 20 women; age range 42~90 years old) who had undergone maxillectomy, mandibulectomy, or glossectomy and were rehabilitated with a maxillofacial prosthesis. The number of functional contact teeth pairs was confirmed by intraoral examination. Chewing rate, cycle duration, coefficient of variation (CV) for cycle duration (reflecting the stability of masticatory rhythm), and mixing ability were measured simultaneously using a mastication movement rhythm tracking device during gum chewing. Maximum occlusal force was measured using the dental prescale system. Patients' perception of chewing ability was rated using a questionnaire. Results: The Spearman's rank correlation test revealed that mixing ability, patient-rated masticatory scores, cycle duration, CV for cycle duration, and maximum occlusal force showed significant correlations with chewing rate. Multiple linear regression analysis identified mixing ability and the CV for cycle duration as significant predictors of masticatory rhythm. Conclusions: Factors associated with a faster chewing rate were higher mixing ability and masticatory scores, greater maximum occlusal force, shorter cycle duration, and smaller CV for cycle duration. Stable masticatory rhythm and mixing ability are significant predictors of chewing rate. Poor masticatory performance and unstable masticatory rhythm can result in slower chewing and thus a higher risk of inadequate dietary intake.

Ultrashort Implants, Alternative Prosthetic Rehabilitation in Mandibular Atrophies in Fragile Subjects: A Retrospective Study

This study aimed to evaluate the effectiveness of using ultrashort implants in the rehabilitation of jaws of fragile patients. The aim of the study was to retrospectively evaluate the survival rate of full-arch prosthetic rehabilitation on ultrashort implants, length 4 mm, 4 mm in diameter in the premolar and canine area and 4.5 mm in diameter in the molar area, with the insertion torque of 60 Nw and immediate loading. Nineteen patients were evaluated for 3 years clinically and radiographically. The significant majority of the patients at the 3 year follow-up (T4) presented a stable and functional implant-supported prothesis, and the survival rate of the implants was 85%, with a loss of 16 implants on 114 implants. The combination of the innovative implant surfaces and the correct project of the prostheses, with the related implant connection, determined a different timing in the therapy, allowing to obtain an immediate loading, which is currently demanded by patients. This and recent reports on short and ultrashort implant usage in atrophic jaws offer a good solution in critical cases. In conclusion, within the limits of the study, the full-arch rehabilitation with immediate loading on ultrashort implants showed good results with few postoperative complications and related low biological cost.

Influence of Different Repair Acrylic Resin and Thermocycling on the Flexural Strength of Denture Base Resin

Background and Objectives: Fractured acrylic denture base is a common occurrence in clinical practice. The effective denture repair procedure is cost-effective, time conserving, and results in lesser time without denture for the patient. Along with various reinforcements and surface modifications; different acrylic resins are investigated in improving the flexural strength of the fractured site. The aim of this study was to evaluate the flexural strength of a polymethyl methacrylate (PMMA) denture base repaired with heat-polymerized (HPA), auto-polymerized (APA) and light-polymerized acrylic (LPA) resins after thermocycling. Materials and Methods: Forty rectangular shaped (50 mm × 25 mm × 3 mm) PMMA specimens were fabricated. Group 1 specimens (n = 10) were kept as controls and the remaining 30 samples were sectioned at the center with a repair site dimension of 3 mm. The samples from three groups (n = 10) were repaired with HPA, APA, and LPA resins, respectively. The specimens were thermocycled for 5000 cycles and subjected to a three-point flexural test. The maximum load required to fracture the specimens was recorded, and further analyzed with ANOVA and the Games-Howell Post hoc test at the significance level p = 0.05. Results: The average maximum load and flexural strength of the control group was 173.60 N and 13.02 Mpa and corresponding values for denture repaired with HPA was 87.36 N and 6.55 Mpa. The corresponding values for APA resin and LPA resins were 62.94 N, 57.51 N, and 4.72 Mpa, 4.06 Mpa, respectively. Conclusions: The PMMA specimens repaired with HPA resins resulted in a significantly higher load to fracture compared to APA resin and LPA resin.