Generally, it is possible to affirm that the higher stress levels of students compared to the general population data could be related to the commitment and challenges of their “job”, and is consistent with previous literature [7–9].
In addition, the finding of a higher bruxism prevalence for students in respect of the general population data appeared to be consistent with current literature. Even if there is a limited number of studies, a recent review has shown [13] a prevalence ranging from 8 to 31.4%., and the highest prevalence of the above mentioned review was found in the Italian general population [14]; moreover, recent literature has shown levels of bruxism up to 83% in dentistry students [15].
The main findings will now be discussed separately, with them being:
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(i)
the correlation between stress and bruxism in university students;
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(ii)
the presence of a gender difference in stress for university students;
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(iii)
the presence of a gender related correlation between stress and bruxism only in male university students.
The correlation between stress and bruxism is reported in current literature: for example, this finding was reported in a previous study on occupational stress [16], and, more specifically, in university students stress can induce neuromuscular alterations in the mouth and jaw, increasing the general prevalence of temporo-mandibular disorders [17].
Bruxing subjects differ from healthy individuals in the presence of stress sensitivity [13], with daytime teeth clenching (BRUX1) significantly being explained by experienced stress [18], while sleep bruxism (BRUX2) is considered a sleep movement disorder of central origin [13].
In terms of studies in the specific college/university setting, an association between bruxism and stress has been shown [5, 19–22], and literature reports an increase in the incidence of self-reported nocturnal bruxism in college students over the last decades [5] with recent literature reporting also very high values, as we mentioned above [15].
The presence of a gender difference in stress for university students is also consistent with current literature: the majority of the studies reported stress as being higher for female students [16, 23–25]. In our study, the higher prevalence of stress for female subjects living in their own family could be explained by the higher psychological pressure and expectations, and could also plausibly connected with the higher stress levels for female subjects who do not smoke and have not experienced drugs, according to the possible action of the former as a stress reliever and the latter as an escape from reality.
Previous studies have shown that bruxism in the general population is predominant among females [26], and in students there is also a higher prevalence for females [16, 27–30], which we have confirmed in our study, either for BRUX1 and BRUX2, even if the gender difference was not statistically significant.
The presence of a gender related correlation between stress and daytime bruxism (BRUX1) in M gender subjects could be the most innovative part of the research and may be useful to stimulate further studies.
In fact, a correlation between stress and BRUX1 in the male subjects was found, with the higher values being for those living away from their families and for the non-smokers. This could be explained by the higher psychological pressure on males who have to face the challenge of university life as well as manage living on their own, while it is the opposite for females, who experience more stress when living with their own families.
Being a non-smoker may play a similar role between the genders, but with different outcomes: non-smoking females have higher stress levels, but no correlation with bruxism, while non-smoking males have lower stress levels but show stress under the form of awake bruxism.
On the contrary, sleep bruxism (BRUX2) did not show significant correlation with stress, in accordance with the different etiology of these two disorders.
A possible explanation could be related to the pathophysiological factors [4] modulating the bruxism: it is a multidimensional phenomenon, [31] mainly regulated centrally [32] and associated to perceived stress [33].
On these bases, we hypothesize a possible cascade.
It could start from the psychosocial factors, tied to stress, and then could act via central factors, tied to neurotransmission from the brain to the chewing muscles.
These could transfer the burden of stress on the teeth through peripheral factors, and these could finally cause the occlusion interferences.
The fact that in our study BRUX1 does correlate with stress while BRUX2 does not, may be considered a further demonstration of the etiological difference between these two conditions.
