Investigation of the variability of the pterygomandibular space from the point of view of the target point of the inferior alveolar nerve block

INTRODUCTION

A thorough knowledge of the anatomy and variability of the pterygomandibular space (PMS) is essential to the success of local anesthesia. This study is aimed at determining the volume of the PMS depending on the shape of the skull, face and mandible using the computed tomography (CT).

MATERIALS AND METHODS

anonymized computed tomograms of 48 adult patients were analyzed, the indicators of the cranial index (CI), facial index (FI) according to Yzard, the high lengthy index of the mandible (HLI), the latitudinal-altitude index of the mandible (LAI), the longitudinal latitude index of the mandible (LLI) were calculated.

RESULTS

Differences in the volume of the PMS were found depending on the shape of the skull, face and mandible. When determining the CI, the largest volume of space on the right was observed with brachycrania (2.05 ml), on the left - with mesocrania and brachycrania (2.0 ml each). With regard to the FI, the largest volume of space was obtained with medium face on the right side (2.03 ml) and broad and medium types of faces (2.0 ml each) on the left. When calculating the indicators for the shapes of mandible, the largest volume of space was found in the brachygenic (2.05 ml), leptogenic (1.98 ml) and platigenic (1.97 ml) shapes on the right and leptogenic and platigenic shapes on the left (2.0 ml each). There were statistically significant differences in the volume of the right side of the PMS between different shapes according to the cranial index (F = 5.075; p = 0.0095). The most pronounced difference was present between samples with brachycrania and dolichocrania: 0.35 mm³ (95% CI 0.05-0.65); p = 0.0188. There was a statistically significant correlation with sex for parameters on both the right and left sides. The values of indicators in men exceeded those of measurements obtained from women.

CONCLUSION

The data obtained determine the differences in the volume of the PMS in individuals with different shapes of the skull, face and mandible, as well as sex differences. Thus, indicating the need to take into account these features when choosing the required amount of anesthetic in clinical practice. The average volume of the PMS space, according to our data, is 1.8-2.0 ml, which is consistent with the clinical data described in the literature.

Biomechanical analysis of the cervical spine segment as a method for studying the functional and dynamic anatomy of the human neck

BACKGROUND

Traditionally, dynamic and functional anatomy, in particular the dynamic anatomy of the neck, is studied on cadaveric material. However, the development of in vivo visualization technologies and in silico modeling has made it possible to expand these possibilities. Despite significant progress in the study of dynamic and functional anatomy of the neck by means of in silico methods, the issues of validating the developed models and taking into account the pronounced nonlinearity of soft tissues as well as local anisotropy remain open. The aim of this study was to develop a virtual dynamic anatomical model of the human neck and reproduce the dynamic processes in the cervical spine from this model using the finite element method.

MATERIALS AND METHODS

Reverse engineering was used to generate a dynamic anatomical model of the neck from CT data (both male, 24 and 22 years old). Two segments of the cervical spine (C3-C5, C2-T1) were isolated from the resulting model for finite element analysis. Finite element mesh generation and contact interactions were performed using the HyperMesh software (Altair Engineering Inc, Troy, Michigan, USA). The anisotropic hyperelastic Holzapfel-Gasser-Ogden model was used to describe the material behavior of the fibrous rings of the disc. Material modeling and finite element analysis were performed using Abaqus CAE 6.14 software (Simulia, Johnston, Rhode Island, USA).

RESULTS

A technique for creating a virtual dynamic anatomical model of the neck was elaborated and implemented. The model includes 79 major anatomical structures of the neck segmented from radiological data. A finite element analysis of the cervical spine was performed. The results of finite element analysis of the C3-C5 segment under axial load were compared with in vitro data. The proposed model shows nonlinear deformation of the disc under static loading; the model predicted displacement values agree well with the experimental ones. The displacement of the С3-С5 central vertebra with an axial load of 800 N reaches a value of 0.65 mm. For the segment C2-T1, data on intradiscal pressure, stress plots and displacements during flexion were obtained. The maximum stress value of 10.036 MPa is observed in the C3-C4 disc.

CONCLUSION

Simulation results using the proposed methodology are in good agreement with experimental data. The generated biomechanical models allow describing dynamic phenomena in the cervical spine and obtaining a wide range of quantitative properties of anatomical objects, which are otherwise inaccessible to classical methods for studying dynamic and functional anatomy.

[Terminological and debatable issues of the intraosseous organization of the anterior part of the mandible]

In the scientific literature, one can find conflicting assumptions about the presence of «proper mental bone» and «upper and lower lingual canals», which make up a separate ossified area in the chin of the mandible and the system of blood supply and innervation. However, calling these lesions «lingual canals» or «incisal canals», as is often found in various articles, is incorrect based on the position of International Anatomical Terminology. This is due to the lack of topographic reference in the term, which can equally be understood as the canal of the tongue, the neurovascular bundle of the same name, and the root canal system of the teeth of the lower jaw and can also be associated with the maxilla. We searched for information in English, without time limits, in the PubMed Central database, and searched on Google and analyzed the bibliography, relevant studies and reviews. The selection of publications was carried out by request «mental spine canals», 58 articles were found in PubMed, of which 21 were relevant. For the analysis, publications were selected that described in detail the anatomical, clinical and radiological features of the structure of the anterior part of the mandible. As a result of previous studies and the study of literature data, the intraosseous structures of the anterior part of the lower jaw were refined and classified, which solve not only terminological disputes, but also are important clinical guidelines for endodontic treatment, dental implantation and local anesthesia.

[Evaluation of the effectiveness of the compression method for infiltration anesthesia of the mandibular molars]

AIM

To study the depth of analgesia and the electrical excitability dynamics of the pulp of the tooth under local anesthesia without and with compression on the depot of local anesthetics.

MATERIALS AND METHODS

87 men and 93 women took part in the study, the average age of men was 36.8±5.02 and the average age of women was 30.43±2.14. According to the indications, local anesthesia of infiltration type with and without compression at the depot of local anesthetics was performed. The injection was carried out with a solution of 4% articaine with epinephrine1:100000 or 1:200000. Patients were divided into 2 groups depending on the used concentration of the vasoconstrictor with 4% articaine. The target area thermometry and electroodontometry (EOD) of the first mandibular molar were performed. The criterion for the onset of pulp analgesia was the value from 92 to 100 mA.

RESULTS

Dynamics of change in pulp electrical excitability of the first molar with the use of 4% articaine with epinephrine 1:200000 without a compress showed that in the latter case the reduction of pulp electrical excitability to 96.6 µA, which is optimal for painless treatment, was developed by the 5th minute of the study and remained at the limit of 92.2-92.1 µA for 20 minutes. When using 4% articaine 1:100 000 it was noted that also the compression technique allowed to reach the necessary reduction of EOD indices to 93.5 µA by the 5th minute of the study, and to 97.2 µA by the 10th minute. Increased hypothermia in the injection depot area was noted thermographically, especially when high concentrations of epinephrine were used.

CONCLUSION

Our own studies reflect the dynamics of change in the electrical excitability of the pulp of the first molar with the use of 4% articaine by compression method more intensively reduces the electrical reacrivity of the dental pulp depending on the concentration of the epinephrine: with the use of 1:100000, the advantage of the pressure technique is 19.3% and 1:200000 - 21.8%.

[Evaluation of dentists regulatory systems stress during the provision of dental care according to pulse oximetry data]

OBJECTIVE

To evaluate the status of individual hemodynamic parameters (HR) and respiratory indicators of dentists performing local anesthesia. Material and methods. In the period from April 2019 to December 2019 the determination of heart rate (Heart rate) and blood saturation at 120 doctors aged 25-55 years was performed. The value of blood saturation by non-invasive pulse oximeter technique: SpO₂ measurement range 0-99%; heart rate range 18-300 beats per minute. The limit of 95-98% was considered normal. However, we consider it correct to note the introduction of an error of 0.1% due to the constant wearing of a dentist's tight polymer mask. All subjects were preliminarily determined by Robergs-Landvere formula: maximum heart rate (MF)=205.8-(0.685·age).

RESULTS

Maximum HR limits for the groups of subjects were 185.6±3.1 beats per minute in the first group; 178.7±3.1 beats per minute in the second group; 171.5±3.4 beats per minute in the third group. In all groups the tendency to decrease blood saturation in case of pain appearance in patients during treatment against the background of block anesthesia, as well as during anesthesia on the mandible was determined. The definition of SpO₂ showed a slight downward trend in blood saturation when pain occurs within normal parameters. Thus, the limit of changes in the index against the background of performed local anesthesia on the mandible was 95.2-96.1% and 96.3-96.6% on the maxilla.

CONCLUSION

Measurement of arterial oxygen saturation in dentists showed a tendency for a slight decrease in this indicator within the normal range when the patient developed pain. Thus, the limit of changes in the indicator against the background of local anesthesia on the lower jaw was 95.2-96.1%, on the upper jaw - 96.3-96.6%.

[The role of optimal nutrition in the prevention of cardiovascular diseases]

A balanced diet has always been part of a set of preventive measures with cardiovascular diseases (CVD). The aim of the research is to present relevant international data on the role of nutrients in reducing the risk of CVD. Results. This article discusses current data on the effect of consumption of saturated and unsaturated fatty acids, trans fats, cholesterol, dietary fiber, protein, edible salt potassium, magnesium and vitamins on the state of the cardiovascular system and the prevention of CVD. Recommendations on optimal nutrition are given to reduce cardiovascular risks, including those according to the new 3rd edition of the Guide to Cardiovascular Medicine (The ESC Textbook of Cardiovascular Medicine, 3 edn). Conclusion. When managing patients with cardiovascular diseases, it is necessary not only to take into account international nutritional recommendations, but also to focus the patient's attention on how to comply with them.

[Objective assessment of mental nerve local anesthesia]

AIM

To study the reaction of the mental nerve to selective stimulation of thin nerve fibers by thermal stimuli during conduction anesthesia.

MATERIAL AND METHOD

The pilot study involved 24 healthy volunteers: 13 subjects were injected with a 4% solution of articaine-containing anesthetic with a vasoconstrictor in a ratio of 1:200 000 (pH 4.8-5.4) and 11 subjects - a 3% solution of mepivacaine-containing local anesthetic without a vasoconstrictor (pH value 5.8-6.4). The registration of evoked potentials was performed twice: before local anesthesia and 5 minutes after anesthesia. With the help of disposable carpal dental injectors, local anesthesia was performed near the mental foramen in order to anesthetize the innervation region of the mental nerve through a conductive type. The evoked potentials (VP) were recorded on a Nicolet instrument (USA) with Bravo evoked potentials software. The study of thermal EPs was performed using a Contact heat evoked potential stimulator (CHEPS) device ('Medoc Ltd, Ramat Yishai', Israel). The base and peak temperature were set at 33 and 54 °C, correspondingly.

RESULTS

The evoked potentials for thermal stimulation demonstrated a significant decrease in the amplitude of all components and the elongation of the LP of the main negative-positive N2-P2 complex after anesthesia compared with the initial thermal EP. The complete disappearance of thermal responses was observed in 14 (58%) of 24 study participants, minor changes were seen in 3 (12.5%) cases only. The total response disappearance was observed in 10 (77%) of 13 participants after articaine and in 3 (27%) of 11 - after mepivacaine (p<0.05), weak changes were registered in 2 (15%) cases in the articaine group and in 1 (9%) case in the mepivacaine group.

CONCLUSION

A 4% solution of articaine is somewhat more effective for pain relief of teeth and bone since it often causes deeper anesthesia, and a 3% solution of mepivacaine without a vasoconstrictor is physiologically more suitable for working with soft tissues.

[Possibilities of thermographic rating the level of microcirculation with local anesthesia in dentistry]

It is known that the reduction of blood vessels by epinephrine that are part of the local anesthetic leads to a decrease in oxygen intake and the development of hypoxia, which has a significant effect on the excitability of nerve fibers. This is due to the fact that epinephrine is present in the local anesthetic cartridge, which helps to reduce, until termination, microcirculation in the depot area, which leads to local hypothermia. With the introduction of local anesthetics, the temperature of which is significantly lower than the depot temperature, the patient experiences severe discomfort, which is associated with unsuccessful local anesthesia. The goal of the study was the need to analyze the feasibility of using the thermography method in assessing the degree of ischemia of the soft tissues of the maxillofacial region against the background of local anesthesia with a different concentration of epinephrine in dentistry.

MATERIAL AND METHODS

In the pilot study, 22 healthy volunteers aged between 29-35 years of both sexes participated. To assess the degree of external vasoconstriction, a buccal region was chosen near the maxilla. Infiltration anesthesia was used with a 4% solution of articaine with epinephrine 1: 100 000 and 1: 200 000 at a dosage of 0.5-0.7 ml. The temperature distribution in the study area was estimated using a thermal imager Nec InfReC Thermo Gear G30.

RESULTS

The study showed that the use of epinephrine in local anesthetics naturally has a moderate effect on hemodynamics in areas adjacent to the anesthesia depot. When using a low concentration of epinephrine (1:200 000), the projection hyperthermia of the skin is determined. Perhaps this is due to the activation of microcirculation due to an increase in capillary blood flow in the region above the zone of action of the epinephrine. From the point of view of physiological arterial hyperemia, this mechanism carries positive properties, since leads to an increase in tissue oxygenation. When using a high concentration of epinephrine (1:100 000), the zone of hypothermia of the skin is determined, which corresponds to the phenomenon of angiospastic ischemia.

[Topographic features of lingual nerve and its relationship with other anatomical structures in maxillolingual groove]

By surgical interventions in maxillolingual groove area one should consider anatomical variations and topography of vessels, glands ducts and lingual nerve to prevent their injury. At the Department of Operative Surgery and Topographic Anatomy of the First Moscow State Medical University named after I.M. Sechenov we carried out anatomical study on cadavers (men and women, n=30).The study revealed topographical features of the lingual nerve and its relationship to other anatomical structures in the maxillolingual groove. It was found out that at the level of the second molar (96%) lingual nerve "crosses" duct of submandibular salivary gland, at the level of the third molar lingual nerve is located under the duct and lateral to it, closer to the inner surface of the body of the mandible. At the level of the first molar lingual nerve is located above and medial to Wharton duct and passes along sublingual-lingual muscles (m.hyoglossus).

[Scientific anatomical rationalefor lower teeth local anesthesia]

The article presents clinical recommendation for the choice of local anesthesia techniques in dental treatment of lower teeth based both on original research and literature review. Several localanesthesiatechniques are described for various teeth group, as well as intraosseousdiffusionoflocal anesthetic at various sites of mandible bone and possible anatomical reasons for local anesthesia failures. Theresultsofauthor's anatomical and clinical studies confirm that branches of buccal and lingual nerve can provide lower teeth innervation. Several local anesthesia techniques which may be useful for overcoming the mandibular block failure are proposed.

[TRANSPLANTATION OF TRACHEAL-LUNG COMPLEX IN EXPERIMENT]

The article described the developed and patented method of removal of trancheal-lung complex from dead body and its transplantation to the recipient-corps.

[Posterior thoracotomy in ventral decubitus]

The rigidity of the chest wall, thank to its bone framework, determines the variety of operative access in thoracic surgery, both thoracoscopic and open. The posterior thoracotomy on the bed of the resected rib in ventral decubitus is traditionally but gratuitously rarely used access. The method permits comfortable access to trachea, bifurcation, main bronchi and thoracic esophagus. It can also be used in cases of foregoing thoracothomy. Authors own the experience of 111 cases with the use of posterior thoracotomy in ventral decubitus. The access proved to be preferable for the operations on the membranous part of the trachea and main bronchi, some localizations of thoracic tracheoesophageal fistula. The access suggests fast mobilization of the root of the lung without foregoing pneumolisis, which is important in cases of pleural cavity obliteration after tuberculosis or pleural empyem.

[Retromolar mandibular anesthesia. Radiological and topographical study of an additional method of lower teeth anesthesia]

The aim of the study was to estimate the clinical efficacy of mandibular third molars anesthesia with various combinations of local anesthesia methods. Anatomical, radiological and morphological methods were used in the study. The topographic features of retromolar triangle were thoroughly examined. The neurovascular bundle revealed its relationship with retromolar area structures. According to the results of the clinical study the most effective combinations of mandibular third molars analgesia were selected.

[Anatomical and radiological studies on additional mandible teeth anesthesia considering innervation variability]

The paper presents studies on nutritional foramina of the mandible. Some nutritional foramina located in the frontal mandibular region on the lingual surface and containing significant blood vessels and nerves are found to be more typical for teeth-bearing mandible. In retromolar area in case of third molars presence intraosseous canals were revealed leading to inferior alveolar nerve canal. One should consider intraligamental and lingual anesthesia by lower incisors extraction. Intraosseous anesthesia and retromolar area infiltration significantly increase anesthesia efficiency by third molar extraction.

[Side face part computer modelling use as background for low invasive access for TMJ puncture]

Computer modelling of the anatomic structures of different parts of maxillofacial region helps to widen surgeon's possibilities when planning and carrying out operative interventions, to improve doctor's training and to optimize students education in medical institutions. The use of 3D computer modeling for side face parts as the background for low invasive access for TMJ puncture. Results of the practical use of the worked off access (on 3D modell) to the upper part of TMJ confirm the practical efficacy of computer modelling.

[Computer modelling and topographo-anatomic substantiation of TMJ ankylosis surgical treatment]

Results of topographo-anatomic research of lateral and deep area of face with the use of three-dimensional computer modelling was presented. Application of the received data at operations of patients with ankilosis of the temporomandibular joint gave good results. It allows to draw a conclusion of possibility of this technique in a wide clinical practice.

[Mandibular contracture as a complication of trigeminal third branch anesthesia]

Wide use of local trigeminal third branch anesthesia not rarely leads to mouth opening restriction. There is no common opinion on etiology and pathogenesis of this complication, that explains also the absence of treatment algorithm for such patients depending upon length of the process development.

[Topographic-anatomical bases of the use of the inferior epigastric artery in creation of free graft for aortocoronary shunt]

Ten experiments were conducted on nonfixed human cadavers of males and females 50 to 70 years of age. The inferior epigastric artery arises from the medial wall of the external iliac artery 1.0-1.5 cm proximal to the inguinal ligament. Its diameter at the site of its origin varies from 2.5 to 4.0 mm and is 3.25 +/- 0.13 mm on the average. At the level of the umbilical ring the average diameter of the artery is 1.47 +/- 0.03 mm. The total length of the arterial segment which can be used for transplantation varies from 11 to 16.5 cm, being 14.60 +/- 0.48 cm on the average. An approach through an inferomedian incision of the abdominal wall is preferable. The transplant is taken out together with the veins and the surrounding connective tissue. The length and diameter of the inferior epigastric artery are sufficient for using it as an aortocoronary shunt in revascularization of the myocardium in patients with ischemic heart disease.