Globally implant therapy is currently accepted as a predictable, viable and successful option to replace missing teeth. Ample studies have shown excellent survival and clinical success rates of dental implants for various indications.The correct three-dimensional (3D) positioning of an implant is considered a prerequisite for an optimal outcome.Computer assisted implant surgery maybe beneficial in patients with limited bone and proximity to anatomic structures.Therefore, the aim of this randomized controlled clinical trial is to investigate the accuracy of implant position achieved with static CAIP(Computer Assisted Implant Placement) and to compare this with the accuracy of conventional cast based partially guided implant placement(cPGIP).

Globally implant therapy is currently accepted as a predictable, viable and successful option to replace missing teeth.As a result, the focus in contemporary implant dentistry has shifted towards the optimization of treatment concepts with aesthetics and function as an important outcome parameter.In this respect, implant installation should be prosthetically -driven, at the same time taking into account anatomical limitations as well as restrictions in terms of bone availability. Apart from aesthetics, a correct implant position may reduce biological and technical complications, favourable esthetic and prosthetic outcome, long term stability of peri-implant tissues, optimal occlusal contacts and implant loading. One possible tool that may facilitate a more accurate implant positioning is guided implant surgery.Virtual implant planning facilitates desired inter implant distance and depth. A top down planning wherein digital images of the edentulous area and mock wax up of the prosthesis is superimposed, allows precise implant placement planning. This digital planning can be converted into a surgical/virtual guide via a 3D printer or a milling machine.Fully guided surgery is based on a surgical guide which will assist the clinician in every step of the surgery starting from the first drill to the implant placement through the use of guiding sleeves in the guide. A partially-guided protocol differs only in the final step: after guided preparation of the osteotomy, the guide is removed and the implant is installed free-handedly.Therefore, the aim of this randomized controlled clinical trial is to investigate the accuracy of implant position achieved with static CAIP(Computer Assisted Implant Placement) and to compare this with the accuracy of conventional cast based partially guided implant placement(cPGIP).

Inclusion Criteria:

• Patients in need of replacement of missing teeth.
• Mouth opening at least 30 mm.
• Age>18 years.
• Limited vertical or horizontal dimension of the alveolar ridge.
• Unfavorable bone morphology necessitating correct implant position.
• When minimally invasive (e.g. flapless) surgery is intended.
• When immediate implant restoration is planned.

Exclusion Criteria:

• Heavy smokers (more than 10 cigarettes per day)
• Uncontrolled diabetes
• Metabolic bone disorders
• History of radiotherapy of the head and neck
• Recent chemotherapy
• Use of drugs influencing bone or soft tissue healing (e.g., high doses of antiresorptive medication, steroids or anti-inflammatory drugs)
• Pregnant and/or lactating women