## 5 Topical Curcumin-Based Formulations in Oral Diseases
### Other Inflammatory Conditions  
Turmeric-derived compounds have also been reported as effective in other inflammatory conditions localized in the mouth. One of them is oral lichen planus (OLP), an autoimmune chronic inflammatory disease affecting mostly buccal mucous membranes but also tongue and gums. The exact etiology of lichen planus remains unknown. The disease is associated with the occurrence of various lesions in the oral cavity, combined with pain, burning sensation and discomfort. OLP is considered a premalignant condition [165]. The available literature data suggest that topical curcumin formulations can be useful in the treatment of OLP-related lesions. However, the comparative studies performed with the use of curcumin-based formulations and topical corticosteroids do not provide sufficient evidence for the replacement of steroidal therapy with curcumin [166; 167]. It is also noteworthy that oral curcumin administration did not result with any clinical improvement [168; 169]. Another chronic premalignant condition localized in mouth is oral submuc fibrosis (OSF). The most important symptom of the disease is abnormal collagen deposition resulting in fibrosis, ulceration, xerostomia and significant discomfort accompanied with restricted tongue mobility, dysphagia and reduced mouth opening. Among the most important risk factors contributing to the occurrence of OSF, chewing betel nut is mentioned. However, alcohol consumption, tobacco use, immunological comorbidities and vitamin and iron deficiencies can also be significant etiology factors [170]. Most of the available literature reports regarding the topical use of curcumin in OSF reveal improvement in clinical manifestations of the disease [148]. The observed effects were either comparable or better than those recorded for standard topical steroids therapy [171; 172]. The results of the most important studies focusing on the application of different curcumin-based formulations in the conditions localized in the mouth are summarized in Table 2. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Condition** & **Dosage Form** & **The Most Important Findings** & **Reference** \\ \hline Periodantal disease & collagen sponges & \(\bullet\) & anti-inflammatory results similar to chlorheximide-based treatment & [117] \\  & & \(\bullet\) & the efficacy decreased after 3 months & \\ Periodantal disease & nanoparticles & \(\bullet\) & antimicrobial effect comparable to chlorheximide treatment & [120] \\  & & \(\bullet\) & clinical parameters improvement without decreasing the levels of interleukin-1\(\beta\) (IL-1\(\beta\)) in the saliva of interleukin-1\(\beta\) (IL-1\(\beta\)) in the saliva & [121] \\  & & \(\bullet\) & no significant improvement was observed in the group with additional curcumin treatment & \\ Periodantal disease & PLGA and PLA nanoparticles & \(\bullet\) & the lack of significant effects was most probably related to low drug concentration and formulation leak & [122] \\ Periodantal disease & nanoparticles & \(\bullet\) & bone repair and collagen content were significantly improved in the group treated with curcumin nanoparticles & [123] \\ Periodantal disease & \(\bullet\) & quick curcumin release in the initial stage followed with sustained release & \\  & & \(\bullet\) & good antimicrobial effect against & [124] \\  & & \(\bullet\) & _Perhyromonas gingialis_ & \\ Periodantal disease & PLGA nanoparticles (injection) & \(\bullet\) & inhibition of inflammatory bone resorption in rats with induced periodontitis & [125] \\ Periodantal disease & in situ-forming gel & \(\bullet\) & good efficacy as an adjuvant therapy bleeding and periodontal probing depth reduction & [126] \\  & & \(\bullet\) & the results were comparable to the adjuvant tetracycline therapy & \\ Periodantal disease & topical gel & \(\bullet\) & additional osteogenesis and healing potential & [127] \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Curcumin-based formulations investigated in different oral conditions.