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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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=== Introduction === | === Introduction === | ||
The term ''text neck'' was proposed by a chiropractor, Dr. Dean L. Fishman,<ref>Neupane S., Ali U.I., Mathew A. Text neck syndrome-systematic review. Imp. J. Interdiscip. Res. 2017;3:141–148. [Google Scholar] [Ref list]</ref> and it is used to define both a bad postural position and a syndrome associated with the prolonged and inappropriate use of handheld mobile devices, including smartphones.<ref name=":0">Fiebert I., Kistner F., Gissendanner C., DaSilva C. Text neck: An adverse postural phenomenon. Work. 2021;69:1261–1270. doi: 10.3233/WOR-213547. </ref><ref name=":1">Cuéllar J.M., Lanman T.H. “Text neck”: An epidemic of the modern era of cell phones? Spine J. 2017;17:901–902. doi: 10.1016/j.spinee.2017.03.009.</ref><ref name=":2">Moreno M.A., Hoopes A.J. Technology and Adolescent Health: In Schools and Beyond.Academic Press; Cambridge, MA, USA: 2020. The impact of digital media; p. 367.</ref> This adverse postural phenomenon can be described as a sustained flexed neck position, with the head tilted forward. It is associated with forward-rolled shoulders, which increase the curve of the thoracic spine. <ref name=":0" /><ref name=":2" /> Compared to the neutral posture, the higher neck flexion angle requires an increased activity of the neck muscles in order to compensate for the effect of gravity.<ref>Ailneni R.C., Syamala K.R., Kim I.S., Hwang J. Influence of the wearable posture correction sensor on head and neck posture: Sitting and standing workstations. Work. 2019;62:27–35. doi: 10.3233/WOR-182839</ref> These biomechanical changes in the cervical and thoracic spine, as well as muscular imbalances and postural compensations, finally lead to cervical muscle fatigue and pain. <ref name=":0" /><ref name=":1" /> | The term ''text neck'' was proposed by a chiropractor, Dr. Dean L. Fishman,<ref>Neupane S., Ali U.I., Mathew A. Text neck syndrome-systematic review. Imp. J. Interdiscip. Res. 2017;3:141–148. [Google Scholar] [Ref list]</ref> and it is used to define both a bad postural position and a syndrome associated with the prolonged and inappropriate use of handheld mobile devices, including smartphones.<ref name=":0">Fiebert I., Kistner F., Gissendanner C., DaSilva C. Text neck: An adverse postural phenomenon. Work. 2021;69:1261–1270. doi: 10.3233/WOR-213547. </ref><ref name=":1">Cuéllar J.M., Lanman T.H. “Text neck”: An epidemic of the modern era of cell phones? Spine J. 2017;17:901–902. doi: 10.1016/j.spinee.2017.03.009.</ref><ref name=":2">Moreno M.A., Hoopes A.J. Technology and Adolescent Health: In Schools and Beyond.Academic Press; Cambridge, MA, USA: 2020. The impact of digital media; p. 367.</ref> This adverse postural phenomenon can be described as a sustained flexed neck position, with the head tilted forward. It is associated with forward-rolled shoulders, which increase the curve of the thoracic spine. <ref name=":0" /><ref name=":2" /> Compared to the neutral posture, the higher neck flexion angle requires an increased activity of the neck muscles in order to compensate for the effect of gravity.<ref name=":5">Ailneni R.C., Syamala K.R., Kim I.S., Hwang J. Influence of the wearable posture correction sensor on head and neck posture: Sitting and standing workstations. Work. 2019;62:27–35. doi: 10.3233/WOR-182839</ref> These biomechanical changes in the cervical and thoracic spine, as well as muscular imbalances and postural compensations, finally lead to cervical muscle fatigue and pain. <ref name=":0" /><ref name=":1" /> | ||
The scientific literature demonstrates that any change in the head and neck posture induces a change in the rest position of the mandible,<ref>Darling D.W., Kraus S., Glasheen-Wray M.B. Relationship of head posture and the rest position of the mandible. J. Prosthet. Dentistry. 1984;52:111–115. doi: 10.1016/0022-3913(84)90192-6</ref> in the activity of the masticatory muscles,<ref>Boyd C.H., Slagle W.F., Boyd C.M., Bryant R.W., Wiygul J.P. The effect of head position on electromyographic evaluations of representative mandibular positioning muscle groups. CRANIO® 1987;5:50–54. doi: 10.1080/08869634.1987.11678174.</ref> and in the habitual path of mouth closing.<ref>Goldstein D.F., Kraus S.L., Willams W.B., Glasheen-Wray M. Influence of cervical posture on mandibular movement. J. Prosthet. Dent. 1984;52:421–426. doi: 10.1016/0022-3913(84)90460-8.</ref> In an interesting study, Yamada et al. (1999) found that as the head bended forward (i.e., in ventroflexion), the closing path approached the ''maximum intercuspation position'' (MIP) from the anterior region.<ref>Yamada R., Ogawa T., Koyano K. The effect of head posture on direction and stability of mandibular closing movement. J. Oral Rehabil. 1999;26:511–520. doi: 10.1046/j.1365-2842.1999.00386.x. </ref> The forward bending of the head also decreased the stability of the closing path. On the other hand, as the head was bent backward, the closing path approached the MIP from the posterior region and its stability increased. | The scientific literature demonstrates that any change in the head and neck posture induces a change in the rest position of the mandible,<ref>Darling D.W., Kraus S., Glasheen-Wray M.B. Relationship of head posture and the rest position of the mandible. J. Prosthet. Dentistry. 1984;52:111–115. doi: 10.1016/0022-3913(84)90192-6</ref> in the activity of the masticatory muscles,<ref>Boyd C.H., Slagle W.F., Boyd C.M., Bryant R.W., Wiygul J.P. The effect of head position on electromyographic evaluations of representative mandibular positioning muscle groups. CRANIO® 1987;5:50–54. doi: 10.1080/08869634.1987.11678174.</ref> and in the habitual path of mouth closing.<ref>Goldstein D.F., Kraus S.L., Willams W.B., Glasheen-Wray M. Influence of cervical posture on mandibular movement. J. Prosthet. Dent. 1984;52:421–426. doi: 10.1016/0022-3913(84)90460-8.</ref> In an interesting study, Yamada et al. (1999) found that as the head bended forward (i.e., in ventroflexion), the closing path approached the ''maximum intercuspation position'' (MIP) from the anterior region.<ref>Yamada R., Ogawa T., Koyano K. The effect of head posture on direction and stability of mandibular closing movement. J. Oral Rehabil. 1999;26:511–520. doi: 10.1046/j.1365-2842.1999.00386.x. </ref> The forward bending of the head also decreased the stability of the closing path. On the other hand, as the head was bent backward, the closing path approached the MIP from the posterior region and its stability increased. | ||
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==== Examination Procedure ==== | ==== 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. | 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. | ||
[[File:Stoica 2a.jpeg|center|thumb|500x500px|Figure 2: ('''a''') Measurement of the neck flexion angle with a manual goniometer in NHP; ('''b''') T-Scan registration in NHP.]] | |||
[[File:Stoica 3.jpeg|center|thumb|500x500px|Figure 3: ('''a''') Measurement of the neck flexion angle with a manual goniometer in TNP; ('''b''') T-Scan registration in TNP.]] | |||
Further on, the subjects were instructed on how to adopt an NHP. Then they were asked to text for 60 s on their mobile phones, in order to relax and get accustomed to the TNP. For most of them, the mandible went into the postural position (with the freeway space between the dental arches) during texting, but each one of them swallowed at some point in MI, which was the position we followed in our research. The data from the dental literature showed a mean spontaneous swallowing frequency of 0.98 swallows/minute for healthy young subjects.<ref>Bulmer J.M., Ewers C., Drinnan M.J., Ewan V.C. Evaluation of spontaneous swallow frequency in healthy people and those with, or at risk of developing, dysphagia: A review. Gerontol. Geriatr. Med. 2021;7:23337214211041801. doi: 10.1177/23337214211041801.</ref> | |||
{{Bib}} | Each occlusion was objectively assessed by the same examiner by using the T-Scan III system (Tekscan Inc., Ann Arbor, MI, USA), following a standardized protocol. Thus, the standing subject was asked to hold the scanning handle and to adopt an 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. A second examiner measured ''the neck flexion angle'' of the subject in NHP with a manual goniometer. This neck flexion angle is defined as the angle between a vertical line raised from the C7 spinous process and a line connecting the C7 spinous process to the mid-tragus.<ref name=":5" /> The subject was instructed to forcefully clench on the sensor while the T-Scan occlusal registration was made. No pain was elicited in the masticatory system or in the cervical area. In the following phase, each subject was asked to further flex his neck forward, till she/he reached a neck flexion angle that was 30° higher than the angle measured in NHP. A new T-Scan registration was made in this TNP. | ||
The digital occlusal analysis of each patient was preceded by mock registrations that allowed the patient to get accustomed to the procedure. At the same time, we could adjust the sensitivity of the T-Scan III system in order to ensure that its force recording range was matched to the “bite strength” of each individual patient.<ref name=":6">T-Scan III Manual. [(accessed on 1 July 2022)]. Available online: [https://archive.org/details/manualzilla-id-5684279 <nowiki>https://archive.org/details/manualzilla-id-5684279[Ref list]</nowiki>]</ref> We changed the sensor before taking the actual recordings. | |||
The T-Scan III movies were saved and labeled in a way that blinded the data collectors who analyzed those movies. Thus, they did not know in which head and neck position each of the recordings was made. | |||
==== Data Collection and Statistical Analysis ==== | |||
The distribution, force, and timing of occlusal contacts were analyzed in MI and in static intercuspation. The latter was defined by Kerstein as the moment of the last tooth contact during the closure of the mouth, which is marked as the Bline on the registration. It is different from the MI, which appears later.<ref name=":6" /><ref name=":7">Kerstein R.B., Grundset K. Obtaining measurable bilateral simultaneous occlusal contacts with computer-analyzed and guided occlusal adjustments. Quintessence Int. 2001;32:7–18. </ref><ref name=":8">Kerstein R.B. Handbook of Research on Clinical Applications of Computerized Occlusal Analysis in Dental Medicine. 1st ed. IGI Global; Hershey, PA, USA: 2015. T-Scan 8 recording dynamics, system features and clinician user skills; pp. 95–151. </ref> The maximum intercuspation was analyzed in the maximum area frame of the registration (MA). In an ideal occlusion, the MA frame is also the frame where the ''maximum movie force'' (MMF) occurs. | |||
The first analyzed occlusal parameter was ''occlusion time'' (OT)—Figure 4b and Figure 5b—defined by Kerstein as the elapsed time (in seconds) measured from the first occlusal contact (A line) until the last tooth contact in static intercuspation (B line) during mouth closure.<ref name=":7" /><ref name=":8" /> The T-Scan III system was set at a normal OT value of under 0.3 s (“within range”); the “borderline range” was 0.3 to 0.5 s.<ref name=":6" />{{Bib}} | |||