## 4 Subgingival Fractures
### Treatment  
Tooth loss is not necessarily the outcome of this type of fracture. Healing and the absence of symptoms together with a positive response to pulp testing have been reported [23; 24]. Three types of healing have been described:  
_1. Calcified tissue formation_: This is normally observed in the case of minimal displacement of the fragment. The pulp remains responsive to thermal stimuli. Cement, dentin and bone tissue contribute to the stabilization of the fracture. Tertiary dentin forms in the canal. _2. Connective tissue formation_: Periodantal ligament fibres surround the two fragments with the formation of a new apex at the coronal fragment. _3. Bone and connective tissue formation_: This type of healing is normally observed when there is more distance between the two fragments. 3. A. Subcrestal Attachment Level fracture (SAL)--cervical third. Treatment options #1: Root Canal Treatment, Crown lengthening, Restoration. The treatment is similar to that of subgingival horizontal supracestal fractures and involves endodontic treatment, crown lengthening and tooth restoration [21; 25; 26]. However, a proper radiographic assessment should guide the treatment since an unfavourable crown/root ratio (more than 1:1) or an aesthetic impairment represents possible limitations to a crown-lengthening procedure. Treatment options #2: Extraction and replacement with implant therapy or adhesive restoration  
In the case of a complication or a lack of other therapeutic options, implant therapy represents a reliable option. [PERSON] et al. replaced single edentulism due to dental trauma, reporting 97.5% success at a 5-year follow-up [27]. However, in the case of young subjects, rehabilitation might need to be postponed to allow completion of the bone growth in order to avoid implant infra-position due to further growth of the alveolar process and the consequent permanence of the implant in a more apical position with evident aesthetic and functional repercussions. In this case, or in the case of a reduced amount of bone thickness, an adhesive restoration (Maryland Bridge) represents a possible definitive alternative for the resolution of a single edentulism in an aesthetic area. Ridge augmentation and/or orthodontic treatment (_implant site development technique_) might be required to increase and recreate an adequate space/volume for implant placement [28]. Root retention can be also an option to maintain the ridge volume in cases where the presence of infection can be excluded [27]. 3. B. Subcrestal Attachment Level fracture (SAL)--middle third This is the most frequent type of root fracture [22]. Treatment option #1: Monitoring  
Considering the high healing potential (80%) and 86% long-term survival, a conservative approach is preferable [29; 30]. In the absence of mobility, no further action should be taken. Alternatively, a repositioning of the fragment and its splinting is required for an average time of 3-4 weeks [31]. In cases of an open apex, splinting is not suggested as, in this instance, hard tissues will drive the healing. Regular pulp tests and radiographic assessment will be needed to exclude necrosis [3; 32; 33; 34]. Treatment option #2: Endodontic treatment of the coronal fragment  
The pulp of the apical fragment normally remains vital, while the cervical part could easily necrotize [35]. In this instance, RCT of the coronal fragment is indicated. Executing am RCT also in the apical portion of the tooth is not likely to succeed due to debris accumulation in the fracture rim [33; 36; 37]. However, the large diameter of the canal at the fracture point and the presence of diastasis might not allow good disinfection and adequate root filling. Additionally, the contaminated tissue might not be completely removed, causing inflammation of the surrounding area. The use of calcium hydroxide or MTA has been suggested to stimulate hard tissue healing [34; 36; 38; 39].