Clinical Assessment of All Ceramic Single-retainer Using Upper Canine as Abutment With Minimum Preparation on the Lingual Surface, to Replace the Upper Lateral Incisor and Will be Compared With the All Ceramic Single-retainer Using Upper Central Incisor.

The intervention will be all ceramic single-retainer Resin Bonded Fixed Partial Denture using the upper canine as abutment with minimum preparation on the lingual surface within the enamel providing maximum area for the retainer bonding, to replace the upper lateral incisor and will be compared with the control/comparator group which is the all ceramic single-retainer RBFPD using the upper central incisor.

This intervention will be done by one investigator in all study groups who has master degree in fixed prosthodontics with eight years of experience. The intervention will be carried out in the clinic of the department of Fixed Prosthodontics, Cairo University under supervision of PhD holder staff members. The self-adhesive dual cure resin cement will be used for cementation in all groups.

In the first session, the participant will be informed about all steps from the beginning to the end. All participants will be encouraged to maintain good oral hygiene and attend the regular follow up visits and in case of any complain related to the investigated restoration.

Inclusion criteria

• Patients who have unilateral or bilateral missing upper lateral incisor and need to replace them with the following criteria:
• From 14-30 years old and be able to read and sign the informed consent document.
• physically and psychologically able to withstand conventional dental procedure
• Sound or minimally restored abutment with enough enamel surface area for bonding and no periodontal diseases.
• If the patient had previously undergone orthodontic treatment, a stabilization period of at least 3 months before impression taking.
• Good oral hygiene.
• Able to return for follow-up examinations and evaluation.
• No signs and symptoms of bruxism.

Exclusion criteria

• Pregnant women
• Increased overbite
• Bruxism, clenching or abnormal habits like nail or pencil biting that create occlusal forces
• Any developmental anomaly affecting the enamel of upper central incisor or canine
• Uncontrolled caries and periodontal disease and uncooperative patients. 6- Medically unfit for dental treatment and follow up.