The rationale for conducting this study is to compare between three implant drilling systems (conventional sequential system, single drilling system and osseodensification surgical drills) for implant site preparation in the posterior maxillay region through measuring implant stability and bone density around dental implants. Therefore, the primary objective of this study is to evaluate the primary and secondary implant stability performed by the three types through measuring implant stability quotient (ISQ), whereas the secondary objective is to assess marginal bone loss, the operation time for the osteotomy preparation, and finally bone density through measuring grey values on CBCT around implants for all drilling methods at different evaluation intervals of the study.

Primary stability is a critical factor that determines the long-term success of dental implants. It is responsible for preventing the micro- motion of the implant in the bone site, promoting natural healing and effective bone formation until adequate biological stability has been established. Primary stability of dental implants is highly dependent on implant design, surgical technique and the bone density and quality. Conventional implant shaping drills are widely used because they are easy to handle, time-efficient, and not expensive. Nevertheless, the heat that they generate might cause tissue damage, necrosis to the surrounding structures, difficulty in providing a proper three-dimensional positioning and the risk of invading and injuring important anatomical structures such as the inferior alveolar nerve and the Schneiderian membrane. Hence, several studies introduce different techniques and methods to resolve these problems. Recently, new hollow drill in a single drilling system was developed. It was hypothesized that hollow drill design with single drilling system results in decreasing the time for surgery (faster implant placement) and minimum bone removal for implant site preparation. Moreover, it was found that it reduces bone trauma, micro-fractures and allow fasters healing time. Moreover, the hollow design of the single drilling system allows harvesting of the bone core, that bone which result during the osteotomy site preparation can be used in bone grafting as autogenous bone grafting material. Osseodensification (OD) is also a new method of biomechanical bone preparation performed for dental implant placement. The procedure is characterized by low plastic deformation of bone that is created by rolling and sliding contact using a densifying bur that is fluted such that it densifies the bone with minimal heat elevation. OD, a bone nonextraction technique, was developed by Huwais 2013 and done using specially designed burs (Densah™ burs) that help densify bone as they prepare an osteotomy these burs provide advantages of both osteotomes combining the speed along with improved tactile control of the drills during osteotomy.

Inclusion Criteria:

1. Patient between 20-50 years old.
2. remaining bone height of more than 8 mm, remaining bone width of 6 mm
3. Adequate keratinized soft tissue.
4. Favorable pattern of occlusion.
5. Good oral hygiene.
6. Patient ability to comply with the required recall visits

Exclusion Criteria:

1. Insufficient bone width (less than 6 mm) mesiodistal or buccolingually.
2. Patients having any uncontrolled systemic disease which could affect bone healing.
3. Patients treated with radiotherapy to the head and neck area within the past 12 months.
4. Heavy Smokers (more than 20 cigarette per day) according to WHO.
5. Inability or unwillingness to return for follow-up visits.