Vol 28, No 5 (2024)

Background: For implant-supported restorations, clinicians use both original and non-original abutments, which are widely available in today’s dental market. The finite element analysis previously conducted by the authors revealed that the microgap size in a taper connection depends on the selected abutment and affects the state of the marginal bone surrounding the implant.

Aim: To determine the distinguishing factor between original and non-original abutments that has the greatest impact on the microgap size in a taper connection during masticatory force modeling.

Materials and methods: The study used Straumann Bone Level (BL), BioHorizons Tapered Internal, and NobelParallel Conical Connection (CC) implants and standard abutments, as well as non-original ADM Dental abutments. Before conducting a serial computational experiment, the geometric parameters of the samples were manually measured. In the first stage of the study, four main factors were identified: screw material, abutment material, screw geometry, and abutment geometry. The calculations were based on the authors’ earlier research findings and were performed using finite element modelling with the Mechanical module of the ANSYS Workbench software.

The NeoScan N80 microtomography system was used in the second stage of the study. Moreover, the microgap size and length of cone generatrixes between the components were measured to better understand the geometry of the samples. The results were processed using the DataViewer and CTVox (Bruker Micro-CT) software.

Results: The abutment geometry had the greatest impact on the microgap size of a taper connection in both the Straumann BL and BioHorizons Tapered Internal systems. In the NobelParallel CC system, the abutment screw geometry had a greater impact on the microgap size. The microtomography findings revealed a difference in the length of implant-abutment cone generatrixes for the Straumann BL (0.1 mm) and BioHorizons Tapered Internal (0.07 mm) systems, with no difference between the original and non-original abutment for NobelParallel CC implants. The cone generatrix of the screw is smaller with the original NobelParallel CC abutment compared to the non-original one. This is the only negative difference value (–0.34 mm), with the modulus significantly exceeding that of the difference between Straumann BL (0.2 mm) and BioHorizons Tapered Internal (0.2 mm).

Conclusion: The study revealed that selecting an original versus non-original abutment has a greater impact on the microgap size of a taper connection due to differences in abutment geometry, particularly the geometry of its fixing screw.

Background: The biomechanical conditions under which teeth, implants, and bone tissue function clearly determine their resistance to overloading and subsequent destruction. However, mathematical modeling has not previously been used to compare functional stress in teeth across a wide range of sensitive biomechanical load conditions.

Aim: To compare the stress-strain state parameters of tooth and socket tissues under various biomechanical load conditions.

Materials and methods: A mathematical model was used to assess the stress-strain state parameters of dental tissue and sockets under vertical and oblique load (150N) with various modeling settings, compared to reference model parameters. The following parameters were assessed: enamel attrition, bone density reduction, bone resorption by 30% and 50%, supra-occlusion, tooth cavity, composite restoration, and ceramic inlay.

Results: Enamel attrition significantly increases stress under vertical and oblique loads: 1.9 and 1.6 times for enamel, and 1.5 and 1.2 times for dentin, respectively. Tooth cavities increase stress by 1.2 and 1.8 times (enamel; vertical and oblique loads, respectively), and 1.3 times (dentin; vertical load). Increased functional load causes a proportional increase in stress in hard tooth tissues and adjacent bone tissues. Supra-occlusion causes a sharp increase in stress in the enamel, with a point stress concentration. When a tooth cavity is filled with a composite or ceramic material, the stress-strain state parameters are similar to those in intact teeth (however, the enamel still experiences a 1.5-fold increase in stress under vertical pressure).

Conclusion: 3D mathematical modeling revealed a significant difference in maximum stress in tooth and socket tissues compared to normal biomechanical conditions, as well as when comparing various sensitive load conditions. Stress in tooth and bone tissues increased in all cases of abnormal biomechanical conditions, especially when oblique load was applied.

Background: Infectious-allergic, neurogenic, occupational, immunological, and crossover factors play a significant role in the etiopathogenesis of chronic recurrent aphthous stomatitis (CRAS). Moreover, CRAS is associated with chronic kidney disease (CKD) and viral infections of the oral cavity secondary to urogenital pathologies.

Aim: To assess the efficacy of comprehensive diagnosis and treatment of CRAS in patients with urogenital infections.

Materials and methods: The study included 120 patients with CRAS aged 18–70 years. Of these, 80 had CRAS secondary to CKD with infectious complications: treatment group 1 (TG1, n=40) and reference group (RG, n=40). Forty patients with CRAS had no urogenital infections: treatment group 2 (TG2). The treatment protocol in the study groups included antihistamines, sedatives, immunomodulators, and multivitamins. Topical treatment included Eludril solution (irrigation, mouth wash, etc.), as well as ginger and myrrh extracts. The conditional control group (CCG) included 20 apparently healthy subjects.

Results: The study found that regional lymphadenitis, Mikulicz’s aphthae, swollen oral mucosa, severe dental caries, and a high periodontal disease index were more common in patients with CRAS secondary to CKD; patients with more prolonged and severe CRAS had the worst results. Immunodeficiency and abnormal blood chemistry findings associated with CKD were identified as the primary pathogenetic factors for recurrent infection in CRAS.

Conclusion: Patients with CRAS secondary to CKD may develop chronic inflammation caused by opportunistic pathogens in the oral cavity, resulting in local immunodeficiency, which is largely determined by the site and severity of inflammation.

Background: Psychoemotional stress is one of the most significant risk factors in many pathological conditions.

Aim: To assess the incidence and severity of psychoemotional stress in patients with abnormal occlusion.

Materials and methods: The severity of psychoemotional stress was assessed in 120 patients with abnormal occlusion. A dental examination using primary and secondary methods was performed in all patients. Following a clinical examination, the patients were divided into three groups based on the severity of dental attrition (according to Bushan, 1979). The Russian version (according to Vodopianova) of the Psychological Stress Measure (PSM-25; Lemyr–Tessier–Fillion) was used to assess the severity of psychoemotional stress. The questionnaire included 25 questions with an 8-point score for the interpretation of answers, with 1 point representing the absence of psychoemotional stress symptoms and 8 points representing constant daily emotional stress.

Results: The analysis revealed that 42 patients had enamel attrition (Group 1), 49 patients had enamel attrition with partially affected dentin (Group 2), and 29 patients had severe attrition that exposed the dentin (Group 3). All respondents reported experiencing varying levels of psychoemotional stress in their daily lives. The severity of stress increased with more severe clinical manifestations of abnormal occlusion. Moreover, the study revealed that the incidence of psychological stress of varying degrees was 100%. The most common manifestations of psychological stress in patients with abnormal occlusion were as follows: grinding and clenching habit (mean: 3.080±0.099 in Group 1, 4.870±0.185 in Group 2, and 6.080±0.122 in Group 3); feeling unwell (mean: 4.020±0.072, 5.620±0.107, and 6.02±0.12, respectively); fatigue (mean: 4.310±0.103, 5.920±0.124, and 7.310±0.263, respectively); and sleep disorders (mean: 5.280±0.121, 5.690±0.165, and 6.280±0.151, respectively).

Conclusion: The severity of stress can be used as an integrated quantitative measure of an interdisciplinary approach in the management of these patients, highlighting the need for specialist consultations to improve the psychological status. The severity of stress is an objective efficacy criterion for the diagnosis and treatment, reflecting changes in the level of psychological stress.

Background: Muscle and joint dysfunction is a common complication, particularly in females over 40 years. It is strongly associated with age-related hormonal changes in the bones, as well as concomitant dentoalveolar deformities and tooth loss.

Case description: The efficacy of combination treatment of dentoalveolar abnormalities and deformities complicated by temporomandibular joint (TMJ) dysfunction was demonstrated. The efficacy of combination treatment in patients with missing teeth, as well as dentoalveolar abnormalities and deformities complicated by TMJ dysfunction, was confirmed. To ensure a representative before-and-after comparison, the restoration of masticatory efficiency following orthodontic and orthopedic rehabilitation was assessed.

A physical examination in patient M. revealed hypertonia of masticatory muscles, restricted mouth opening, jaw shifting to the left, partially absent dentition in distal sections, and prosthetic restoration failure. On MRI, there were signs of deforming arthrosis of both TMJs. The following observation methods were used to assess the efficacy of rehabilitation:

1. questioning to identify symptoms of TMJ pain; follow-up examination for joint clicking when opening the mouth;
2. palpation of the external pterygoid muscle, masticatory muscle, and internal pterygoid muscle;
3. X-ray examination (TMJ CT and MRI) following treatment;
4. masticatory efficiency assessment using a masticatory performance test (according to Trezubov) before and after treatment.

Diagnostic testing following combination orthodontic and orthopedic treatment revealed that the patient’s left TMJ no longer felt heavy, and she could open her mouth easily; moreover, jaw shifting resolved, and masticatory muscle rigidity decreased.

Conclusion: This clinical case demonstrates why orthopedic surgeons and orthodontists must collaborate in the diagnosis and treatment of TMJ dysfunction. The authors present a well-established approach to the treatment of patients with TMJ dysfunction that has been used successfully in clinical practice for several years.

Background: Various innovative solutions are being adopted in dentistry to reduce the risk of treatment-related complications. Latest-generation adhesive systems are important for preventing microleakages and improving the adhesion of filling materials to tooth structures, resulting in effective use of esthetic restoration materials and long-lasting restorations.

Aim: To assess the current use of universal adhesive systems.

Materials and methods: The literature search was performed using PubMed, eLIBRARY.RU, and Google Scholar. The following search terms were used: “universal adhesive systems”, “universal adhesives”, “dentin bonding agents”, “dental debonding” and “dental etching”. The search covered studies published during the last 10 years.

Results: The initial search yielded 1.284 publications. After screening for compliance with search terms, 106 studies were selected. Following a full-text analysis, 31 (100%) publications were included in the review. Of these, 14 (45%) studies addressed adhesive composition (examined component: hydrophilic monomers, nanofillers, hydrophobic monomers, solvents, etchants); 8 (26%) studies addressed adhesive strength of adhesives (air-powder abrasive surface treatment, smear layer characteristics, surface moisture, bonding agent type, testing conditions); and 9 (29%) addressed application method (etching type).

Conclusion: Universal adhesive systems have a wide range of clinical applications (various methods of surface preparation) and clinical scenarios, expanding their potential use. The findings of the literature review describe various applications of universal adhesive systems with various surface preparation techniques, with mixed results. Conflicting literature data highlight the importance of investigating the long-term use of universal adhesives with various clinical settings and protocols.

The personnel of the Department of Dentistry (after 1942, the Department of Maxillofacial Surgery and Dentistry) of the Military Medical Academy named after S.M. Kirov made major contributions to the advancement of dentistry and maxillofacial surgery in Russia. This essay focuses on the professional life of Associate Professor Moisei Schwartz, Major of the Medical Service, whose research significantly contributed to experimental dentistry and periodontology. The essay uses the data presented in Russian literature on dentistry and maxillofacial surgery, as well as the recollections of dentists who knew Moisei Schwartz personally: V.P. Zabelin, Colonel of the Medical Service, and Associate Professor V.V. Fiolkovsky, Colonel of the Medical Service.

Associate Professor Moisei Schwartz, Major of the Medical Service, performed several studies of the functional properties of jaw vessels, primarily mandibular vessels. He was the first to use the Kravkov–Pisemsky technique in dentistry to assess the effect of biogenic amines on isolated jaw vessels. His comparative studies of ear and jaw vessels in dogs using this technique revealed that jaw vessels are hypersensitive to acetylcholine, histamine, and adrenaline. In 1936, Moisei Schwartz developed an experimental periodontitis model using chronic irritation (ligation) of the inferior alveolar nerve in dogs.

Moisei Schwartz fought in the Soviet-Finnish War of 1939–1940, as well as the World War II (1941–1945).

Moisei Schwartz was a prominent scientist and experienced doctor with good manual skills, including surgical care in maxillofacial wounds. Moreover, he was a passionate researcher and educator. His contributions to experimental dentistry and periodontology are impossible to exaggerate.