الفهرس 
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Abstract
Fourteen male patients with maxillary edentulous ridge and remaining two mandibular canines, one on each quadrant were selected for this study, from the outpatient clinic, prosthetic Department, Faculty of Dentistry, Ain Shams University and approved from Research Ethics Committee.
The decision to extract teeth and replace them with immediate Implant Is determined by many factors such as advanced periodontal attachment loss teeth restored with crowns, loosened endodontic posts, advanced carries, unfavorable crown-root ratio and various combination of these factors contribute to final decision to remove teeth.
To compare the bone height changes around immediately placed implant retaining mandibular overdenture in atraumatic and conventional tooth extractions cases by using parallel technique.
All patients were informed about the study protocol and objectives before they signed informed consent. The included subjects were selected according to the following criteria. Age ranged from 40 to 60, patients were completely maxillary edentulous and have one remaining canine on each side, right and left which were indicated for extraction, Patients have adequate inter-arch space at least 14mm to accommodate the implant-retained mandibular overdenture as well as ball and socket attachment, Availability of bone>2mm apical to the root apex to provide adequate primary implant stability. Patients with good oral hygiene to be a candidate for implant success.
In both groups, there is no significance difference in peri-implant bone height loss between (baseline/After 3 months-After 3 months/6months-After 6 months /12 months) because a great care was taken to maintain the buccal bone during extraction, the placement of implant immediately in fresh sockets will maintain the integrity of the socket and promote faster healing process and proper case selection with adequate labial bone thickness and no signs of periodontitis.
Bone loss in overall of group I and group II revealed a significant difference between all intervals especially over six months, conventional extraction at group I showed (After 6months-12 months) 0.24±0.10mm and (0-12 months) 0.68±0.18mm and atraumatic extraction at group II showed (After 6-12 months)0.07_+0.075mm and (0-12 months) 0.32_+0.07mm so group I was significantly higher than group II because atraumatic extraction technique using piezotomes can reduce the damage and bone resorption as preserving bundle bone during extraction will reduce bone resorption, overcome soft tissue recessions and preserve thick gingival biotype, on the other hand, the forceful tearing of PDL during conventional extraction will interfere vascular blood supply due to loss of PDL, bundle bone becomes non-functional and undergoes complete resorption and results in immediate destruction of alveolar bone and soft tissue structure so lead to further loss of vertical dimension during the first year around immediately implants.