Difference between revisions of "Influence of the Text Neck Posture on the Static Dental Occlusion"

Influence of the Text Neck Posture on the Static Dental Occlusion (view source)

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 A widely debated topic in the literature is whether or not changes in head and neck posture have a significant influence on dental occlusion. However, the effect of ''text neck posture'' (TNP) on occlusion has been overlooked in the dental literature. Chapman et al. (1991) used the T-Scan system to record and analyze the occlusal contacts that occur in ''maximum intercuspation'' (MI) in three different head positions: supine, sitting erect, and sitting with the head tipped forward.<ref>Chapman R.J., Maness W.L., Osorio J. Occlusal contact variation with changes in head position. Int. J. Prosthodont. 1991;4:377–381.</ref> They proved that the mandible is pushed forward during closure when the head is tipped forward, resulting in more anterior initial contacts. However, the total number of occlusal contacts in MI was not significantly modified by the postural change. This means that the main effect of a changed head position was on the initial tooth contacts, which guide the mandible back into MI from eccentric positions. The authors speculated that the location of the first occlusal contacts in the anterior region of the dental arches during closure (i.e., when the head is tipped forward) could produce occlusal overload of the individual teeth. Therefore, they are expected to alter the activity of the elevator muscles.
-In another T-Scan study of mouth closure, Makofsky et al. (1991) found that in subjects 30 years of age and older, a 30° ventroflexion of the head shifted the initial occlusal contacts anteriorly, while a 45° head extension displaced the contacts posteriorly older.<ref>Makofsky H.W., Sexton T.R., Diamond D.Z., Sexton M.T. The effect of head posture on muscle contact position using the T-Scan system of occlusal analysis. CRANIO® 1991;9:316–321. doi: 10.1080/08869634.1991.11678378.</ref> Gupta et al. (2017) reported that the occlusal contact area in MI varies between two different head postures: 90° upright and 30° ventroflexed [12].<ref>Gupta S., Tarannum F., Gupta N.K., Upadhyay M., Abdullah A. Effect of head posture on tooth contacts in dentate and complete denture wearers using computerized occlusal analysis system. J. Indian Prosthodont. Soc. 2017;17:250–254. doi: 10.4103/jips.jips_321_16.</ref> The pressed occlusal contact area (mm<sup>2</sup>) was measured using the Dental Prescale System (Dental Prescale, Fuji Film Co., Tokyo, Japan), a computerized occlusal analysis system used for the measurement and analysis of the bite force (N), the occlusal contact area (mm2), and the bite pressure (MPa). They concluded that the pressed occlusal contact area (mm<sup>2</sup>) decreased in head ventroflexion compared to the upright-erect position.
+In another T-Scan study of mouth closure, Makofsky et al. (1991) found that in subjects 30 years of age and older, a 30° ventroflexion of the head shifted the initial occlusal contacts anteriorly, while a 45° head extension displaced the contacts posteriorly older.<ref name=":3">Makofsky H.W., Sexton T.R., Diamond D.Z., Sexton M.T. The effect of head posture on muscle contact position using the T-Scan system of occlusal analysis. CRANIO® 1991;9:316–321. doi: 10.1080/08869634.1991.11678378.</ref> Gupta et al. (2017) reported that the occlusal contact area in MI varies between two different head postures: 90° upright and 30° ventroflexed [12].<ref>Gupta S., Tarannum F., Gupta N.K., Upadhyay M., Abdullah A. Effect of head posture on tooth contacts in dentate and complete denture wearers using computerized occlusal analysis system. J. Indian Prosthodont. Soc. 2017;17:250–254. doi: 10.4103/jips.jips_321_16.</ref> The pressed occlusal contact area (mm<sup>2</sup>) was measured using the Dental Prescale System (Dental Prescale, Fuji Film Co., Tokyo, Japan), a computerized occlusal analysis system used for the measurement and analysis of the bite force (N), the occlusal contact area (mm2), and the bite pressure (MPa). They concluded that the pressed occlusal contact area (mm<sup>2</sup>) decreased in head ventroflexion compared to the upright-erect position.
 Such studies have proved that physiological head positions, which are adopted naturally by the subjects, have a significant influence on some of the investigated static occlusal parameters, including the number and position of the initial tooth contacts during mouth closure, as well as on the occlusal contact area in MI. It must be pointed out that a 30° ventroflexion of the head coincides with the active feeding posture, while a 45° head extension is used for drinking.<ref>Haralur S.B., Al-Gadhaan S.M., Al-Qahtani A.S., Mossa A., Al-Shehri W.A., Addas M.K. Influence of functional head postures on the dynamic functional occlusal parameters. Ann. Med. Health Sci. Res. 2014;4:562–566. doi: 10.4103/2141-9248.139319.</ref>
 Fewer studies have addressed the effect of abnormal head positions such as the ''forward head posture''(FHP) on dental occlusion. In FHP, the subject pushes her/his head in front of its natural position over the cervical spine, with a simultaneous posterior bending of the head and a compensatory extension of the upper cervical spine, in order to maintain the horizontal direction of the eyes—for example, facing the computer desktop<ref>Patwardhan A.G., Khayatzadeh S., Havey R.M., Voronov L.I., Smith Z.A., Kalmanson O., Ghanayem A.J., Sears W. Cervical sagittal balance: A biomechanical perspective can help clinical practice. Eur. Spine J. 2018;27:25–38. doi: 10.1007/s00586-017-5367-1.</ref> (Figure 1a). Some authors even call this the desktop neck posture.<ref>(accessed on 20 July 2022)]. Available online:  [https://erikdalton.com/blog/text-neck-desktop-neck/ <nowiki>https://erikdalton.com/blog/text-neck-desktop-neck [Ref list]</nowiki>]</ref>
+[[File:Stoica 1.jpeg|center|thumb|500x500px|'''Figure 1:''' ('''a''') Forward head posture (FHP), which is sometimes called the desktop neck posture; ('''b''') text neck posture (TNP)—examples given by one of the examiners in the study.]]
+In a sample of thirty-nine normal subjects, Makofsky (2000) did not find a significant relationship between experimentally induced FHP and the initial occlusal contact pattern that occured while the subject was slowly and completely biting onto the sensor of the T-Scan II Occlusal Diagnostic System.<ref>Makofsky H.W. The influence of forward head posture on dental occlusion. CRANIO® 2000;18:30–39. doi: 10.1080/08869634.2000.11746111.</ref> This result is of interest because the same author proved in a previous study that the initial occlusal contact pattern during closure is influenced by the extension of the head.<ref name=":3" /> It appears that in FHP, which involves a significant degree of head and upper cervical spine extension, the alteration in the mandibular position is not important enough to produce the occlusal changes observed during a physiological head extension. This conclusion has clinical relevance in the treatment of patients with ''temporo-mandibular disorders'' (TMD) and FHP. Some authors claim a relationship between FHP and TMD.<ref>Lee W.Y., Okeson J.P., Lindroth J. The relationship between forward head posture and temporomandibular disorders. J. Orofac. Pain. 1995;9:161–167.</ref><ref>Huggare J.A., Raustia A.M., Makofsky H.W. Head posture and cervicovertebral and craniofacial morphology in patients with craniomandibular dysfunction. CRANIO® 1992;10:173–179. doi: 10.1080/08869634.1992.11677908.</ref> If the initial occlusal contact pattern does not change in FHP, that means that the occlusion is not an etiological factor of the TMD and should not be therapeutically addressed.
+It must be pointed out that FHP is different from the TNP (as pointed out in Figure 1), although they are often incorrectly used as synonyms. Assumed while using a smartphone, the TNP is characterized by a flexed position of the upper cervical region, with the eyes facing downward and fixed on the smartphone<ref name=":0" />—Figure 1b.
+Following the impact of this aspect on today’s population, as well as the shortcomings of the literature on this topic, as pointed out above, the aim of this study was to investigate the influence of TNP on static occlusion in young healthy subjects with normal occlusal relationships.
+=== Materials and Methods ===
+The present study was conducted according to the guidelines of the Declaration of Helsinki. It was approved by CECS no. 70/22.12.2021 of the Ethical Committee of the “Victor Babes” University of Medicine and Pharmacy of Timisoara, Romania.
+==== Study Subjects ====
+A total of nineteen subjects, fifteen females and four males (aged 20 to 24 years), were considered for this research. This sample was chosen for convenience. The process of consecutive selection among young subjects who were interested in a free examination of their masticatory system was based on the following inclusion criteria: full dental arches (except for the third molars in some subjects); normal values of overbite (2 to 4 mm) and overjet (1 to 2 mm); Angle Class I occlusion, without posterior crossbite; healthy periodontal status, with normal physiological tooth mobility; no signs and symptoms of TMD; no pain or limited range of motion in the cervical spine.
+In addition, all standing subjects were able to adopt a ''normal head posture'' (NHP), with the head and back straight and with the external auditory meatus on the same vertical line as the acromio-clavicular joint (i.e., the shoulder), the hip, and the knee. Their head was placed in the midline, with the chin above the manubrium, while their neck had a slight lordotic curve and a normal length, without tilting or rotation of the head.<ref name=":4">Ombregt L.  A system of Orthopaedic Medicine. 3rd ed. Churchill Livingstone Elsevier; London, UK: 2013. Clinical Evaluation of the cervical spine; pp. 119–133.</ref>
+The exclusion criteria were: degenerative or inflammatory spine pathology; fibro-myalgia; cervical spine traumatic events; autoimmune diseases; and neurologic diseases that can have an impact on cervical position. Furthermore, we excluded subjects that currently reported any of the following parafunctions, which can influence the head and neck position by muscle hyperactivity: awake and/or sleep bruxism; nail biting; biting of the cheeks and lips; ventral position during sleep; keeping the phone between the face and the shoulder; playing violin or a wind instrument; maintaining a pencil between the dental arches; tongue pressing on the lingual surfaces of teeth; abusive consumption of chewing gum.<ref>Okeson J.P.  Management of Temporo-Mandibular Disorders and Occlusion. 7th ed. The Mosby Imprint of Elsevier Inc.; St. Louis, MI, USA: 2013. Etiology of functional disturbances in the masticatory system; pp. 102–128.</ref>
+The anamnesis and clinical examination of the masticatory system was based on Schiffman’s “Diagnostic Criteria for Temporomandibular Disorders (DC/TMD) for Clinical and Research Applications”.<ref>Schiffman E., Ohrbach R. Executive summary of the Diagnostic Criteria for Temporomandibular Disorders for clinical and research applications. J. Am. Dent. Assoc. 2016;147:438–445. doi: 10.1016/j.adaj.2016.01.007. </ref> The examination of the cervical area was based on the protocol recommended by Ombregt.<ref name=":4" />
+All subjects were fully informed about the nature of the investigation and signed an informed consent form to participate in this research.
+==== Examination Procedure ====
+At the beginning of the procedure, we explained the different steps of the examination to our subjects without giving any details about the purpose or hypotheses of the research. The images in Figure 2 and Figure 3 present one of the examiners as she demonstrates the NHP (Figure 2) and the TNP (Figure 3) to the study subjects.
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