The present study aimed to assess the oral health status in SSc patients compared with healthy individuals. The results of the meta-analysis indicated that SSc patients have limited mouth opening and worse periodontal status compared with the healthy populations.
The most factor associated SSc and oral manifestations together were the reduced mouth opening, which was caused by the sclerosis of skin and masticatory muscles. The extent of the mouth opening restriction was correlated with various variables, such as gender and disease severity[26]. It was certain that the restriction of mouth opening will affect the quality of lives of SSc patients mostly because of weakened eating abilities and the difficulties in oral hygiene maintenance[27]. According to our findings, SSc patients tend to have higher periodontitis prevalence, and the elevation of periodontal parameters, such as PD and AL were detected in SSc populations. One of the reasons for the declined periodontal status in SSc patients is the restricted mouth opening, which makes it difficult for the patients to maintain daily oral hygiene and for the dentists to conduct the oral exam and dental treatment. Besides, SSc always developed accompanied by the Xerostomia. It was reported that 14 % of the patients might have secondary Sjögren’s syndrome [28]. The insufficient salivary flow decreased the self-clean ability of the oral cavity and impaired the buffer balance, which makes a beneficial situation for bacterial colonization, and contributes to periodontal and dental pathology [29]. Additionally, Esophageal reflux, another concomitant symptom of SSc patients, raised oral cavity acidity and also contributes to the growth of periodontal pathogens [30].
Periodontitis is an inflammatory disorder raised by the accumulation of specific bacterial pathogens and the destruction of host immune responses [31]. The clinical findings of periodontitis included gingival bleeding, tooth mobility, and finally the loss of the tooth, which are associated with a negative impact on Oral Health Related Quality of Life (OHRQoL) [32]. Similarities could be discovered between periodontitis and SSc. Studies suggested that several pathomechanisms might be shared by these two chronic diseases, one of which is the elevated circulating inflammatory biomarkers, such as C-reactive protein (CRP), Tumor Necrosis Factor (TNF)-α, IL(Interleukin)-6, 1, and 17 [16]. The study conducted by Ozcelik et al. showed that the gingival infiltration and microvessel density were elevated in the gingiva samples of SSc patients, however, the vascular endothelial growth factor (VEGF) expressions were decreased, suggesting vessel degeneration [1]. The vascular alterations might inhibit the angiogenic responsiveness to bacteria plaque in periodontal tissues [33], which accelerated the destruction of periodontal ligaments and the surrounding alveolar bones, presenting with increased PD and AL. Moreover, in the researches regarding bone metabolism, the level of soluble receptor activator for nuclear factor kappa beta ligand (RANKL) was reported to be elevated in SSc patients, which was related to osteoporosis in SSc [34, 35]. Similarly, RANKL was also an osteoclast-promoting mediator in periodontitis, which leads to periodontal bone resorption and tooth loss [36].
SSc is a systemic autoimmune disorder that could be substantially companied by psychology and neurological involvement [37]. Additionally, SSc decreased patients’ quality of life in many aspects, including feeling tired, sleep disorders, low self-esteem, as well as ineffective self-care [38]. In turn, the reduction in quality of life might interfere with the treatment and healing of SSc. Oral hygiene instruction and basic periodontal treatments are safe and sound medical choices to improve oral health and oral-related quality of life [39, 40]. Since periodontitis and SSc are both complex chronic diseases that shared similar pathology pathways, the improvement of oral health might contribute to optimal patient management in SSc treatment [41].
The present study is the first evidence-based analysis that quantitively evaluated the association between SSc and oral manifestations. Strengths of the present meta-analysis included the high quality of the eligible studies, with 8 out of 11 studies getting 7 or more NOS scores. The statement of PRISMA was strictly followed and the electronic databases were thoroughly searched. However, several limitations existed therefore the results should be interpreted with caution. First, the present study evaluated the existed literature regarding the association between SSc and oral manifestations. However, because of the rarity of SSc, the number of the included studies was relatively small, hence the publish bias was unable to be performed. Second, significant heterogeneities were observed, which might be caused by geographic and racial diversities. Moreover, all the included studies employed case-controlled designs, therefore the cause-effect relationship between SSc and periodontitis could not be perfectly elucidated.