## 1 Introduction  
Periodontitis is an irreversible chronic inflammation characterized by the destruction of dental support tissues (periodontal ligament and alveolar bone), the presence of periodontal pockets, and gingival bleeding [1]. It can affect up to 50% of the adult population, of which 10-15% suffer the most severe variants [2]. The disease can go through several stages of insertion loss [1] which will affect the aesthetics and masticatory function of the patient and, ultimately, their quality of life.  
The periodontal ligament is made up of collagen fibres that connect the root of the tooth to the alveolar bone and have mechanoreceptors, which are responsible for sending signals to the brain about the forces exerted by the teeth when holding, biting, or chewing food [3]. The loss of periodontal support as a consequence of periodontitis will alter the sensory function of the mechanoreceptors, generating specific dysfunctions in mastication, which can affect the final product of mastication [4]. In addition, there are studies that indicate that both masticatory muscles [5] as well as the bite force of the molars [6] in periodontal patients have less activity than in patients without periodontitis. All of this may result in patients avoiding tough, fibrous, and hard-to-chew foods, potentially leading to malnutrition and systemic issues [7; 8].  
Evaluating the impact of periodontal disease on masticatory function and the patient's quality of life is crucial when diagnosing and treating periodontal patients. For this purpose, there are two types of methods: objective and subjective methods [9]. Objective methods assess the mixing capacity of the food bolus and provide quantitative numerical data, using techniques such as fractional sieving, spectrophotometry, glucose mediators, or digital image analysis of the chewed food during a certain number of masticatory cycles [9]. In contrast, subjective methods allow patients to express their perception of their chewing ability and quality of life, using self-assessment questionnaires, visual analogue scales, or indices based on the perceived difficulty in chewing different types of food [10]. Although some studies have found a significant correlation between both methods [11; 12; 13], others determine a weak or non-existent correlation [14; 15].  
On the other hand, basic periodontal therapy has proven to be effective in treating periodontitis at mild to moderate stages, particularly from a clinical perspective [16], as well as the patient's quality of life [17]. However, there are very few studies that objectively assess the masticatory function of patients with mild to moderate periodontitis and whether it improves after basic periodontal treatment.  
The main objective of this case series study is to determine whether basic periodontal treatment improves masticatory capacity and efficiency in patients with mild-moderate periodontitis, from an objective and/or subjective point of view, and whether there is any type of correlation between both methods. As a secondary objective, we intend to analyse whether variables such as gender, facial patterns, or parafunctional habits influence the results obtained in terms of masticatory efficiency.