## 1 Introduction  
Dental fractures are a disruption of the natural tooth architecture that can involve different portions of the dental structure (crown, root or both) and tissues (enamel, cementum, dentin and pulp). The management of fractures of permanent teeth represents a challenging clinical scenario often requiring an interdisciplinary approach [1]. Unlike injuries located in other parts of the body, the hard dental tissues do not undergo a consequent healing process. Data from a study based on the 1988-1991 National Health and Nutrition Examination Survey (NHANES III) on 7.707 participants aged 6 to 50 years reported a prevalence of 25% of incisors trauma with a mean number of 2 involved teeth and maxillary central incisors as the most frequent site [2]. Enamel fracture was the most prevalent traumatic condition, and a higher occurrence was associated with the male gender and the older age, irrespective of their ethnicity. More recently, the International Association of Dental Traumatology published the guidelines for the management of traumatic dental injuries, reporting that 25% of all school children experience dental trauma and 33% of adults have experienced trauma to the permanent dentition, with the majority of the injuries occurring before age 19 [3, 4]. Luxation injuries are the most common traumatic dental injuries in primary dentition, whereas crown fractures are more commonly reported for permanent teeth [3]. As a consequence, proper diagnosis, treatment planning and follow-ups are important factors in order to achieve successful outcomes.  
Restorative procedures are mostly required to manage such dental defects, and the appropriate placement of restoration margins with respect to periodontal tissues represents one of the most critical aspects of the treatment [5, 6]. [PERSON] et al. focused their systematic review on the interactions between prosthetic dental crowns and periodontal tissues [7]. Their results indicated that a prosthetic crown margin with a supraggingival location was the most beneficial type of restoration in terms of periodontal health. In contrast, restorations with juxta-gingival or subgingival margins resulted in increased plaque accumulation, leading to more severe gingival inflammation, with additional increased pocket depths, loss of attachment and gingival recessions [8; 9]. In this perspective, knowledge of the dimensions of the junctional epithelium and the connective tissue attachment, namely Supracrestal Tissue Attachment (STA), is of paramount relevance [10]. [PERSON] et al. reported that no universal dimension of STA seems to exist [11]. Mean values of STA width were obtained from two meta-analyses and ranged from 2.15 to 2.30 mm, even though large intra- and inter-individual variances were observed. The tooth type and tooth site, the presence of a restoration and periodontal diseases/surgery affected the dimensions of the STA width. Therefore, in the case of combined surgical-restorative approaches to treating fractured teeth, the establishment of a proper STA should be assessed prior to the commencement of the procedure itself. In addition, aesthetic, psychological and functional implications must be also considered [12].  
Even though a wide discussion with useful suggestions has been reported in the recent guidelines for the management of traumatic dental injuries published by the International Association of Dental Traumatology [4], no information was given about the re-establishment of the STA during the different treatment approaches.  
Therefore, the aim of this study is to provide a decisional tree for the treatment of dental fractures in permanent dentition focusing on the periodontal attachment area in order to provide a clinical guide for dental restoration.