Functional assessment and evaluation of health problems with the cervical spine among dental assistants and hygienists

INTRODUCTION

With the rise in the demand for professionally qualified dental care workers, the labor market has seen a rapid growth in interest in dental assistant or hygienist as career options. It is the duty of the dental assistant to reduce the distractions experienced by them, thus significantly easing their daily burden. Older guidelines for dental assistants, such as those described by Jańczuk, “forced” the assistant to work passively in a static position: all activities were performed from a sitting position, without any possibility of moving around [1]. This approach is contrary to the modern ergonomic principles of dynamic work. The professional activities of an assistant entail a very wide range of energy expenditure, with the level depending on the type of contraction in the working muscles, i.e., isometric and isotonic contractions; it is also related to the nature of the job related to repetitive movements.

In some situations, the assistant is required to perform dynamic movements, such as setting the lighting or preparing other specialized instruments needed at a given moment; these may be placed in cabinets located in the treatment room or sometimes in another room. When performed in an appropriate manner, these activities can improve the degree of comfort associated with the work, changing it, as described by Ćwirzeń et al., into a more static-dynamic form [2].

Work-related musculoskeletal disorders (WMSD) among dental professionals have been well documented. As shown by Gandolfi et al. the most affected body areas are the neck (59.9%) and lumbar region (52.1%), followed by the shoulders (43.3%), dorsal spine (37.7%) and wrists (30.6%) [3]. Also, Hayes et al. conclude that WMSD in this professional group ranges between 64% and 93% with the most prevalent regions for pain being the back and neck [4]. Knowledge of WMSD is crucial to the implementation of education in ergonomics among dental professionals, which may be achieved by teaching biomechanics, posturology, integrative functional therapies and by promoting the holistic health of dental operators.

Our hypothesis was that the group of dental professionals under investigation would have poorer cervical spine function (including more pain and limited range of motion) than the control group. The aim of the study was to evaluate the mobility of the cervical spine, pain and function according to NDI score among dental assistants and hygienists, for comparison with the control group.

METHODS

This study was conducted in the period from April 2018 to January 2020. The participants were recruited from the nationwide Asysdent conferences held in 2018 (1090 participants) and 2019 (1040 participants) and the patients of the Osteopathy Centre in Lodz, Poland. Participants that were assessed during the conference in 2018 were not included the following year. All participants of the study were assessed once. The conference attendees comprised a uniform professional group of dental assistants and hygienists. The purpose of the examination was the assessment of cervical spine function and comparison to the group of people without symptoms, whose work does not require extensive cervical spine use. Written informed consent was obtained from the participants before their participation. All participants were informed about the aim of the study, which is to say the analysis of health problems related to cervical spine among dental assistants. The second aim was an analysis of physical exercises and ergonomics at work, and how they influence cervical spine function. However, the results of this second part are the subject of another paper.

The study included 338 dental assistants and hygienists with a mean age of 35.8 years (range from 20 to 60 years) were evaluated. The mean length of service was 10.4 years, the longest was 37 years. All participants were female. No male participant volunteered for the study. Within this group, 195 women were measured with the CROM 3 (Cervical Range of Motion 3) device (mean age 35, range from 20 to 60 years), and 143 were measured using the classic tape measure (CM) (mean age 35.6, range from 20 to 59 years). During the first conference in 2018, the measurement was done with a CM, and during the second one with CROM 3.

The control group was formed of 60 females visiting the Osteopathy Centre for problems related only to the lower limbs. Their professions were not related to extensive cervical spine use, and none had any problems with the cervical spine. This group was divided in half, with 30 being measured with the CROM 3 device (mean age 36.3, range from 22 to 59 years) and the other 30 with a classic tape measure (mean age 38.7, range from 26 to 57 years). The difference in age between study and control group was not statistically significant (for CM and CROM 3, p > 0.05, and p > 0.05; respectively).

All of the women in both groups underwent the same repeatable test procedure. The test itself was performed in a sitting position, with the head in the intermediate position. The functional mobility of the cervical spine was tested by asking every participant to perform maximum fle xion and extension of the cervical spine, as well as a lateral bend to the right and left, and rotations to the right and left.

During the conference in 2018 measurement was performed with classic tape measure. For measurement of maximal flexion of cervical spine, the tape was placed between spinous process of C7 and external occipital protuberance. Measurement of cervical spine extension was done placing the tape between the distal part of the chin and the proximal part of the sternal manubrium. Cervical spine lateral bent to the right and left was measured between the mastoid process of the temporal bone and the distal part of the acromion. For maximal rotations to the right and left distance between the distal part of the chin and the part of acromion was used. The differences in centimeters between intermediate position and maximal investigated positions were noted.

During the conference in 2019 the method of measurement was improved. The CROM 3 device was used instead of classic tape measure. The measurements were easier and faster to perform, as values in degrees were read from the clock face of the device. The device consists of 2 integrated inclinometers and a compass to measure moving components. The inclinometers and compass are firmly attached to human head by plastic holds. Inclinometers measure flexion/extension as well as lateral bent. The compass measures rotation. Inclinometers are adjustable in scale position 0°. The ROM measurements are presented in degrees (Figure I).

Figure I

CROM 3 device for measuring range of motion of cervical spine

Additionally, the participants were surveyed using the Neck Disability Index (NDI) questionnaire [5]. The NDI is a self-report questionnaire, consisting of 10 sections representing 10 activities. For every section, a patient can get from 0 to 5 points (from 0 to 10%). It is used to determine how neck pain affects a patient’s daily life and to assess the self-rated disability of patients with neck pain. A higher score means higher level of cervical spine disability. The subjective level of pain in the cervical region was scored on a ten-point visual analogue scale (VAS) pain score. Zero on the VAS pain score means no pain, higher scores indicate higher levels of pain. The VAS is the patient-reported outcome measure most frequently used to measure pain intensity in back pain trials [6].

The study was performed in accordance with the 1964 Declaration of Helsinki. The study protocol was accepted by the Bioethics Commission of the Medical University of Lodz (RNN/99/22/KE, 10 May 2022).

Statistica for Windows 13.3 Pl was used for statistical analysis. The comparison between groups for age was done with Student’s t-test. The Shapiro-Wilk test was done for normality of distribution check. The Mann-Whitney U test was used to assess statistical significance of VAS pain score between groups. The comparison between the study and control groups for range of motion and NDI score (Tables 1-3) was performed with Mann-Whitney U test. The comparison between the two groups responses to the NDI questionnaire (Tables 4-11) was performed with c² test and Yates’s c² test. For all tests, the level of significance was taken as p < 0.05.

RESULTS

First, a statistical comparison between study and control groups for VAS pain score was performed. In those measured with the CM in the study and control groups (mean 4.0 ± 2.4 and 0.8 ± 1.4; respectively) the difference was statistically significant (p < 0.001). The difference between the study and groups in CROM 3 measurements (mean 4.7 ± 2.1 and 0.3 ± 0.8; respectively) was also statistically significant (p < 0.001). When both groups were taken together (CROM 3 + CM) the difference was also statistically significant (mean 4.4 ± 2.2 and 0.5 ± 1.1; respectively, p < 0.001).

Both CROM 3 and CM measurements identified lower mobility in all measured directions among the dental assistants compared to the other group, as confirmed with statistical analysis (Tables 1 and 2).

The NDI score in the study group was 12.3 points, compared to 2.95 points among the control group (p < 0.001). Worse results were noted also in all subgroups of the NDI questionnaire among dental assistants and hygienists (Table 3).

The results indicate that only 28.7% of the dental professionals, i.e., the study group (total n = 338), indicated a complete absence of pain at the time of measurement, while 12.4% experienced constant, moderate pain as measured with the NDI questionnaire. These results differed significantly between the two groups (Table 4).

Only 31.7% of the study group reported being able to lift heavy objects without feeling pain. In addition, 36.1% reported the occurrence of pain while lifting heavy objects, and 19.8% reported being able to lift only light objects. These results differed significantly between the study and control groups (Table 5).

More than half of the respondents in the study group (56.2%) reported free movement and pain-free work in the dental surgery. Of the remainder, 25.7% reported moderate pain during their duties and 14.8% intermittent pain (Table 6). In addition, only 33.4% in the study group reported not having any problems with sleeping: 8.3% reported two to three hours of insomnia each night, and 3% reported up to three to five hours of insomnia (Table 7).

In addition, 13.9% of respondents in the study group reported mild headaches, and 23.4% moderate headaches. Only 4.4% reported the absence of headaches, while 25.7% indicated frequent, severe headaches (Table 8). Significant problems with concentration were reported by 32.2% of respondents, while only 21.3% indicted that they could fully concentrate on a topic without any problems (Table 9).

The data regarding recreational physical activity are interesting. Out of 338 respondents, only 34.6% did not experience any problems, such as neck pain, during exercise. The remainder indicated feeling neck pain during this kind of activity in various intensities (Table 10).

Furthermore, 10.9% of the respondents in the study group reported being prevented from driving because of moderate neck pain, while 30% could drive with mild neck pain and 23.6% with moderate neck pain. Only 32.4% reported being able to drive a car for as long as they wanted, without feeling pain in the cervical spine (Table 11).

DISCUSSION

Modern dentistry has become increasingly sophisticated, and requires strong, complicated and repetitive efforts by the entire dental team. Indeed, while the efforts of the team can be painful for the patient, this pain is often shared by the dental staff themselves. Studies have noted a growing incidence of cervical spine pain in dentistry, similar to that associated with the overuse of smart-phones [7]. A key component of the dental team is the dental assistant. However, the conditions faced by the assistant in the modern dental surgery result in a greater risk of fatigue, decreased concentration, muscle tension and pain, especially in the cervical spine. This is not surprising, as such duties are characterized by the need to assist for long hours, delivering instruments, working in artificial lighting conditions and small spaces. They are affected by wearing harmful aerosols, protective clothing that restricts movement, as well as risk of needle stick injuries, possible damage to equipment and the responsibility associated with the work [7].

Regarding the increasingly common incidence of degenerative disease of the cervical spine, the position of the Polish Society of Spine Surgeons is that surgical treatment should be offered only after a six-week period of ineffective conservative treatment. Indeed, a review found insufficient evidence to indicate that the benefits of surgical procedures outweigh the risk of complications [8]. Cervical spine pain disorders are one of the most common problems among the adult population, ranking second only to lower back pain. Piątkowska et al. report the occur-rence of pain significantly reducing quality of life in 44% of the Polish population. Long-term static overload and forced head positions have a negative impact on the articular cartilage, resulting in the premature, gradual development of degenerative changes in the cervical segment [9]. These findings confirm ours. We found that patients working as dental assistants had significantly reduced range of cervical spine motion as well as lower results in the majority of the 10 NDI questionnaire sections including: pain, weightlifting, working, sleeping, concentration, physical recreational activity, headache or driving a car.

Our findings are in agreement with other authors, that by assessing health problems, it is possible to determine how an assistant “works” [10-12]. Is the profession of assistant, once that of a helper, ergonomically safe and free of health problems in the neck area? A study of 24 dentistry students found that bending the cervical spine, a position commonly adopted by the dental team, causes pain in the shoulder muscles and the trapezius muscle in 63% of respondents, in the suboccipital muscles in 50%, and in the levator muscles of the shoulder blades in 36% [10], which is consistent with our present findings. A Polish study also found dental practice to have considerable ergo-nomic shortcomings. Among the 79 dentists surveyed, only 4% took breaks at work after each procedure, 84% sat in a forced position during the procedure, and 54% maintained a forced tilt and head rotation to one side [11].

Previous studies have noted that patients with chronic cervical pain demonstrate altered patterns of local muscles recruitment, tending to abuse the polyarticular muscles by engaging them with high contraction force and speed, resulting in an increased activity of the more superficial muscles and lower activity of the deeper ones. Such postural compensations lead to the inhibition of single-joint muscles (stabilizers), which should dominate under light load conditions, i.e., in low-threshold conditions [13, 14]. Women are more prone to strain on the cervical spine, due to their muscles tending to be thinner and softer. The work of the assistant, consisting in the forced positioning of the head, with eyes focused on a bright, small treatment area, combined with various posture errors that appear unconsciously during office work, may result in profound changes to the cervical spine. When in a sitting position, the natural physiological curves of the spine should dynamically adjust so that the line of gravity falls on the support surface. Often, however, the natural cervical lordosis begins to lift, which causes the line of gravity to fall beyond the proper support surface, thus disturbing the balance. This can happen when the assistant tilts the torso and head excessively forward, accompanied by a component of rotation and lateral bends [13, 14].

Our observations indicate the significance of the reduction of the functional range of motion of the cervical spine. Poorer NDI results and VAS pain scores were found among the dental assistants and hygienists in comparison to the control group whose work was not related to cervical spine overuse. In the study group, a greater range of movements was also observed to the right side compared to the left side and this may be closely related to the nature of the space occupied at the dental unit. Similarly, Nowotny-Czupryn et al. report that assistants were more likely to work with the cervical segment rotated more to one side than the dentist herself: 57.5% more often to the right and 42.5% more often to the left [15].

Currently, the most commonly used global classification used to assess the cervical spine is the NDI [6]. NDI have been used in previous studies assessing clinical patterns affecting disability in patient fitness questionnaires [16-18]. Previous studies have also noted that the pathologies associated with the cervical junction become more severe with length of service [15]. A Swedish study of male and female workers identified neck pain in 29.7% of the doctors studied and 24.2% of the assistants. However, as many as 48% of female dentists reported strong pain in the cervical region compared to 32% of assistants [19].

This study has some limitations. First, this is a non-experimental design. Second, two groups of participants were compared (dental professionals versus a control group of non-dental professionals) in which the number of participants were not equal. Third, the two different measurements methods used (CM and CROM3) makes this group non-homogenous for comparison of ROM and different statistical calculations were done for both methods. However, the NDI questionnaire results were not dependent on the measurement methods used.

The results of our study indicate that cervical spine WMSD among dental professionals is a problem we should focus on, to improve their quality of life. Special attention should be paid to improving ergonomics at work and introducing rehabilitation programs together with physical exercises. This knowledge may also help to form educational programs for those professionals. This study will be continued to evaluate the influence of physical exercises and ergonomics, but the results of this will be a subject for another publication.

CONCLUSIONS

Our findings confirm a decrease in the mobility of the cervical spine, lower functional scores involving various everyday activities and greater intensity of pain among dental assistants and hygienists in comparison to research participants whose work does not involve cervical spine overuse.