Abstract:

The introduction of implants to dentistry has helped many edentulous patients to have a more reliable functional and esthetic alternative to fixed and removable prosthetic appliances. The optimal 3-dimensional positioning of the implants secures the best function and esthetic of the final restoration and at the same time avoids the biomechanical complications and failure that might take place subsequent to the wrong positioning of the implants. The aim of this project: is to highlight the importance of placing the implants in the optimal 3-D position. Computer guided template-based implant placement will be discussed as a precise and predictable tool in the planning and in the execution of the implant placement. The objective: is to enable the placement of the implant in a way that secures the highest predictable success with the least complications. Materials and Methods: Out of 350 downloaded relevant articles only 161 articles were chosen and referenced. The excluded articles were either written in languages other than English, descriptive of new fabrication methods of surgical guides, single case reports or experimental done on small sample size{less than 5}. Results: Most of the revised papers are case series or experimental studies done on animals or cadavers. Even the systematic reviews were based on those articles. Computerized tomography (CT) and interactive software programs are proven to be important for accurate treatment planning. The accuracy of transferring the treatment plan precisely by the aid of CAD/CAM fabricated surgical guide to the patient mouth are reported to be more predictable than free hand implant placement especially in the compromised cases. Conclusion: The published literature highlighted the higher predictability, accuracy and precision of computer guided template based implant placement over conventional free hand placement; but supporting strong evidence is lacking. Good controlled clinical studies with long term follow up is needed in this regard. For the time being and with the reported high success of conventional free hand implant placement, it seems that free hand implant placement seems to be predictable at least in the hands of experts or with the uncompromised cases.

Introduction:

In the 19th century many aspects of life were affected by the industrial revolution, especially in sciences and manufacturing. Dentistry was not an exception of this. However, it was in the Victorian era when the basis of modern dental care was first set. A large number of the developments in dentistry were just modifications of industrial inventions. Many of such developments were impossible before the introduction and use of electricity, which led to the invention of more complex surgery equipments {Gelbier S, 2005}. Another very important development took place as a consequence of the invention and the use of computers in the various fields of dentistry {Schleyer Titus K.L., 1999}.Computer guided implant placement is one of the aspects that shows how dentistry has got use to the computer and its science { Azari A. and Nikzad S.; 2008}.

In fact, it is true that the advancement in dentistry and the increased public awareness public of the importance of keeping their teeth healthy have led to the decreased frequency of edentulism. Such declination varies not only among different countries but also among the different geographic regions within the same country and among the different groups of people of different cultural and social backgrounds. However, it is predicted that in the next few decades, there will be very low proportions of edentulism in elderly persons (over 65 years). Teeth loss increases with age, this means that in the future edentulism will occur at later stages in life {Lang NP & Muller F. 2007; Lang N.P.& De Bruyn H., 2009}. In such situations and in addition to the “natural delays” in the healing of elder individuals {Goodson 3rd WH& Hunt TK 1979}; the patients at that age will be most properly affected by co-morbidities and unfavorable ageing conditions like osteoporosis, uncontrolled diabetes mellitus, hypothyroidism and chronic renal disease which are among the diseases that negatively affect the bone quality and consequently implant success. Some older age related diseases like Parkinsonism, Alzheimer can affect the ability to perform adequate oral hygiene and this may lead to inflammation and bone loss around implants {Roberts WE. et al.1992; Elsubeihi ES. & Zarb GA. 2002; Marder MZ. 2004}.For this, dental professionals need to develop their skills and to use new techniques that offer the patients with the safest, accurate results and the least morbidity and to be able to manage such elder patients and their unfavorable conditions which sometimes may preclude the placement of the implants {Lang NP & Muller F, 2007; Lang N.P. & De Bruyn H., 2009}.

Back ground:

Traditionally, lost teeth were replaced by removable partial dentures {RPD}, fixed partial dentures {FPD} and complete dentures in cases of full edentulism { Bragger U et al 2005}. Since the introduction of implants to dentistry by Branemark{1977}, many of the edentulous patients have been able to have more reliable functional and esthetic alternative to fixed and removable prosthetic appliances{Lang N.P. & De Bruyn H., 2009}. The increasing Demand for implant retained restorations in the last few decades resulted in the need for new improved techniques to ensure the most proper implant position to restore the patient properly {Ganz S.D,2001} .

Historically the implants were placed where there is bone { Kopp et al 2003}. They were considered successful when integration is achieved {Branemark et al.1977}. However, as the functional and esthetic demands of the patients have increased significantly; the success of implant-supported restorations is no more only related to the level of implant integration in the bone but also to the proper positioning of the implants and subsequent prosthetic outcome{ Lal et al.2006}. For this proper treatment planning has become mandatory. The main goal of the treatment plan is to place the implants in the optimal position as dictated by function and esthetics of the definitive restoration. This in turn avoids the biomechanical complications and failure that might take place subsequent to the wrong positioning of the implants {Garber DA& Belser UC. 1995; Kopp et al. 2003 & Park et al. 2009}.

The aim of this project: is to highlight the importance of placing the implants in the optimal 3-D position. Computer guided template-based implant placement will be discussed as a precise and predictable tool in the planning and in the execution of the implant placement.

The objective

is to enable the placement of the implant in a way that secures the highest predictable success with the least complications.

Materials and Methods:

Multiple searches have been made through Science Direct and Google Scholar. The following key words were used with different combinations: systematic review, computer-guided, computer-assisted, image-guided, robots, dental implants, complications, treatment planning, radiography, computerized tomography, accuracy, flapless surgery, zygomatic implant, bone density, augmentation volume, immediate loading, free hand surgery, Steriolithographic templates. As the topic of computer guided implant placement is a modern topic; the selected articles were limited to the articles published from the year 2000 up to 2010. However some older but relevant articles were hand searched, selected and referenced. Almost 350 articles were found to be relevant to the different points to be covered in the project were downloaded; after reading their abstracts it was found that many of them were either clinical case series and reports or experimental studies made on animals or cadavers, many of the systematic reviews were found but again nearly all of them were based on the mentioned articles. The articles of single case reports and the experimental studies with very small sample {less than five} size were excluded. Also, the articles that focus on the fabrication of new surgical guides were excluded. Articles in languages other than English are excluded too. Only 161 were selected and referenced in this project.

Results:

Most of the revised articles concerning the accuracy of CAD/CAM template based implant placement are case series or experimental studies done on animals or cadavers. Even the systematic reviews were based on those articles. Based on the revised articles; computerized tomography (CT) and interactive software programs are proven to be important for accurate treatment planning. The accuracy of transferring the treatment plan precisely by the aid of CAD/CAM fabricated surgical guide to the patient mouth are reported to be more predictable than free hand implant placement especially in the compromised cases.

Discussion:

Complications associated with improper implant positioning:

Marginal bone loss and consequent mechanical and esthetic problems:

The correlation of marginal bone loss and improper positioning of the implant is reported in the literature. The wrong angulation of the implant is usually compensated by the use of angled abutments, in this situation the load carried by the implant is mostly off-axis, such unfavorable load leads to the bone destruction around the implant and other mechanical complications like screw loosening, fracture and/or implant fracture {Chun-Li Lin et al., 2005 & Saab X. E. et al 2007}.The improper placement labially, will lead to thin labial bone and subsequent bone loss and gum recession{Buser D. et al. 2004}, lingually, in addition to the thinning of lingula bone it results in emergence problems as seen with ridge-lap restorations. Such restorations are difficult to maintain and consequent inflammation and bone loss is unavoidable {Tarnow DP. 1995; Belser UC. et al. 1998}. The placement of the implant too close to the adjacent tooth can cause resorption of the inter-proximal alveolar crest {Esposito M. et al. 1993; Thilander B. et al. 1999}. If the implant is placed too far apically using extensive countersinking, the polished implant collar will come into contact with the bone and this in turn induces bone resorption because polished surface does not integrate {Buser D. et al. 1991a; Hämmerle et al. 1996}, also the micro gap will come closer to bone and unnecessary bone loss will take place. Disuse atrophy due to subnormal mechanical stimulation is another explanation for bone loss around polished implant neck or crest modulous {Al-Sayyed, A. et al. 1994; Vidyasagar L. & Apse P. 2004}.

Nerve injury:

Altered sensation of the lower lip as a result of inferior alveolar nerve injury is one of the serious complications of mandibular implant osteotomies {Bartling et a. 1999; Vazquez L. et al. 2007}.This is especially if the magnification factor on the panoramic radiograph is misinterpreted {Vazquez L. et al. 2007}.

The injury of the mental nerve can also lead to the same symptoms; the mental foramen is an important landmark during surgical procedures in the lower premolar area. it is usually located at the apex of the second mandibular premolar or between apices of thetwo premolars. However, in some cases its location can vary from the mandibular canine to the first molar. Unfortunately, The foramen may not appear on conventional two dimensional radiographs, in this condition a computerized tomography (CT) scans are important as they are more accurate for the detection of the mental foramen than conventional radiographs { Bartling et a. 1999 , Greenstein& Tarnow, 2006}.

Lingual bundle:

Though it is rare complication, the wrong implant placement in the mandible may lead to the perforation of lingual cortex with a great possibility of lingual bundle injury with a subsequent fatal bleeding and hematoma formation. Under the effect of profuse bleeding and as a result of the progressive expansion of the lingual, sublingual, sub- mandibular, and sub-mental hematomas ; the tongue and the floor of the mouth can be displaced leading to the rapid and complete obstruction of the airway {Mordenfeld A et al. 1997 and Kalpidis & Setayesh , 2004}.

Devitalization of the adjacent teeth:

In addition to the risk of losing the inter-proximal bone {Esposito M. et al. 1993; Thilander B. et al. 1999}; the placement of the implants in close proximity to the adjacent teeth may lead to the loss of the teeth vitality especially if the roots are injured during drilling for implant placement {Jemt T.& Pettersson P. 1993; Rubenstein J.E.& Taylor T.D. 1997; Goodacre CJ. et al. 1999 & Schwartz-Arad D. et al. 2004}.

Other possible rare but serious complications:

Some other rare complications can take place due to poor treatment plan and wrong implant placement like perforation of nasal and sinus floor {Nahlieli O. et al 2008},injury of the submandibular and/or sublingual salivary glands {Nahlieli O. et al 2008},mandibular fracture especially in osteoporotic and atrophied mandible{ Raghoebar G.M. et al.2000 & Meijer H.J.A. et al. 2003}.

Criteria of optimal implant position:

The ideally placed implant should be surrounded by uniform bone volume and density; this provides the implant with a good bony support against the multi directional long term loading. A minimum of more than 1 mm bone thickness is recommended to keep around the body of the implants {Nancy L.C., 1993}. In addition, the implant ideally should be placed in the geometric centre of the crown; this reduces the off axis loading and prevents many of the biomechanical complications and its subsequent poor esthetic outcomes {Galanis C.C et al. 2005& 2007}.

Implant tooth distance:

A minimum of 1- 1.5 mm distance between the implant surface and the adjacent teeth needs to be respected {Buser D. et al 2004}. However, a 3 mm distance between the implant and an adjacent natural tooth is recommended to minimize the potential for damage to the supporting structures of the natural teeth {Adell et al, 1986; Hobo et al, 1989}.

Implant to implant distance:

To avoid bone resorption in-between the adjacent implants; a minimum of 3 mm inter-implant distance is recommended {Hobo et al, 1989& Traini et al. 2007}.

Implant to vital structure distance:

To avoid nerve injury during implant surgery in the mandible, some guidelines should be considered with respect to verifying the position of the mandibular and/ or the mental foramen and to validate the presence of the anterior loop of the mental nerve. These guidelines included leaving a 2 mm as safety zone between the implant and the nerve. Once the safety zone is identified, implants can be placed safely; and before the placement of any implant anterior to the mental foramen that is deeper than the safety zone, the mental foramen must be explored to verify the possibility that an anterior loop is there {Buser &Von Arx 2000, Greenstein& Tarnow, 2006}. In consideration of the risk of surgical complications during implant placement, bone grafting or other surgical procedures where risk is anticipated, a CT examination should routinely be performed before any surgical approach { Ganz S.D,2001; Scaravilli MS, et al 2009& Naitoh et al. 2010}.

To reduce the probability of such serious complication, some preventive measures should be taken before, during, and after implant placement in the anterior part of the mandible, among such measures are the awareness of the regional arterial anatomy, proper treatment planning through radiographic and clinical evaluation of the osseous morphology, and the right angulation and length of the selected implant and finally the skill of the surgeon {Kalpidis & Setayesh , 2004}.

Dental CT is a valuable tool for the assessment of jaw bone anatomy and can easily demonstrate the occurrence, position, diameter and course of the lingual vascular canals of the mandible; for this, a CT examination should routinely be performed before any surgical procedure to the anterior region of the mandible to verify the presence of the mandibular lingual vascular canal {MLVC} and to evaluate the lingual cortical bone thickness and density to avoid perforations and the life threatening bleeding {Scaravilli MS, et al 2009& Naitoh et al. 2010}.

Distribution of the implants in edentulous jaws:

Ideal implant distribution and placement is critical in order to secure the optimal mechanical and esthetic outcome of the definitive restorations as well as enabling the patients to maintain proper hygiene. The placement of the implants in the inter-proximal positions may cause problems from an aesthetic, mechanical and hygiene perspective {Jivarj S., 2006}. Also, the antero-posterior distribution of the implants should allow equal distribution of load over a wide area with minimal cantilever length {Adell R et al. 1990; Palmqvist S et al 1994 & Jivarj S., 2006}. When multiple implants are placed to retain a prosthetic appliance; parallelism between the implants should be secured otherwise the unfavorable off-axis loading will not be avoidable {Arfai N.K. & Kiat-amnuay S. 2007}. In the case of implant and tissue supported overdentures both implant placement and distribution become critical; where the Implants have to be placed so that when a bar is constructed it has a straight line connection between the implants and does not encroach on the palatal/lingual denture bearing area. The distribution of implants should also be in the way so that adequate space is available for the clip {Jivarj S., 2006}. When more force – from the opposing occlusion- on the implants are anticipated more implants should be placed to share the load {Jivarj S., 2006}.

Treatment planning:

Until recently the main concern was directed to the surgical aspect of implant placement {Ganz S.D, 2001}. The implants were planned to be placed where the bone is found {Kopp et al 2003}. The esthetic and functional outcome of the final prosthesis was not much considered {Ganz S.D, 2001}. The new concept of prosthetically driven treatment planning and implant placement requires careful evaluation of the surgical site. In addition, it must relate the 3-D location of the future prosthetic restoration to the optimal 3-D implant position. This position must be discussed and agreed on between the restorative dentist and the dental surgeon {Garber DA& Belser UC, 1995, Kopp et al 2003 & Park et al. 2009}.

In the early days dentists who were believing in this concept {prosthetic driven} were mostly dependant on conventional radiography, wax-up prostheses and/or surgical templates made on the hard stony surfaces of the study casts, and to overcome the problem of transferring the plan to the operative site, customized radiographic and surgical templates have become an integral part of treatment (Becker CM & Kaiser DA. 2000, Almog DM et al.2001}. Very soon later, it was found that the hard surface of casts is not equal to the soft tissue surface of the oral cavity, and this method may not be as accurate as necessary for treatment purposes. Additionally, it was established that templates fabricated on the study cast without knowledge of the exact anatomy below the surface cannot be considered reliable {Lal K. et al. 2006 and Widmann G& Bale JR 2006}.

The traditional tools for the treatment planning of dental implants include detailed clinical examination, panoramic, cephalometric and peri-apical x-ray films, diagnostic wax-up and articulated study models. Other diagnostic aids may include photography and ridge mapping technique for the assessment of the implant bone sites. Advanced diagnostic tools such as tomography, digital radiography, and CT scan film allow for a more accurate pre-surgical evaluation sites { Traxler M. 1992, Tyndall D. A. et al. 2000, Flanagan D. 2001, Ganz S.D,2001, Perez A.M. et al 2005, Guerrero M. E. 2006, Chen Lung-Cheng 2008, Loubele M. et al 2008}.

Study models:

Accurately mounted casts are critical in assessing prosthetic and inter-occlusal space limitations. Spatial constraints must be considered as a matter of practicality {Jivraj S et al 2006}. Study casts are also valuable tool to evaluate occlusion {Hayasaki et al. 2005 } and to help in the treatment planning through diagnostic wax- up {Katsoulis J. et al. 2008}. Moreover, radiographic and surgical templates can be constructed out of such study models {Lal K.et al. 2006; Katsoulis J. et al. 2008 & Rubio-Serrano M. et al 2008}.

Bone sounding

No doubt that the direct measurement {DM} of the ridge size is the most accurate diagnostic tool. However, treatment planning especially in the big cases calls for collecting information before surgery. This saves time and money, avoids the unexpected complicated surgeries like harvesting bone for ridge augmentation and increases the predictability of the treatment. When ridge mapping {RM} is compared to direct measurement {DM} of the ridge size and to Linear tomography {LT} & cone beam computerized tomography {CBCT}; ridge mapping {RM} seems to be the most reliable pre- operative clinical method to determine the ridge size {Perez L.A. 2005 & Chen L.C. 2008}., linear tomography is reported to underestimate the ridge size {Perez L.A. 2005} while cone beam computerized tomography is reported to overestimate the ridge measurements {Chen L.C. 2008}.

However, ridge mapping is not only an invasive procedure but also a difficult to use in the cases of shallow labial and/or lingual vestibules. Additionally, in ridge mapping the actual position of the inferior alveolar nerve cannot be verified {Perez L.A. 2005 & Chen L.C. 2008}.

Conventional two – dimensional radiography:

Actually, conventional 2-D radiography {panoramic, cephalometric and intraoral views}, which is widely used for the treatment planning, has important diagnostic limitations, such as magnification and distortion, setting errors and position artifacts {Tyndall D.A. & Brooks S.L.; 2000& White SC et al, 2001}. Moreover, these 2-D radiographs do not show lingual anatomy or provide complete three dimensional (3-D) information about the dental arch {Nikzad and Azari. 2008 }. These limitations make the 2-d radiography is less than optimal tool for the diagnosis and treatment planning of dental implants; where according to recommendations provided by The American Academy of Oral and Maxillofacial Radiology (AAMOR), The aim of the preoperative dental implant treatment planning is to place the optimum number and size of implants to secure the best prosthetic outcome. This can be achieved only if a thorough knowledge of the patient’s bony anatomy in 3- dimensions is provided in the radiographic examination .

Proper treatment planning requires that the clinician evaluate the suitability of the remaining bone for placement of implants. The clinician must determine if there is enough height, density, width of bone, and an appropriate axis of orientation for a successful prosthetic outcome { Tyndall D.A.& Brooks S.L 2000& White SC et al, 2001}.

CT scanning

Although Computerized Tomography {CT} scans have been used in the medical field since 1973; it was not before 1987 when this new technology became available for dental purpose {Ganz S.D, 2001}. In implant dentistry; Computerized Tomography {CT} scan is one of the most important diagnostic tools which significantly improved the clinician’s ability to diagnose and to put accurate treatment plan because it helps in viewing the anatomy and dental related anomalies of the jaws {Dula K. et al. 1994; Abrahams JJ& Berger SB,1998 & AbrahamsJ.J.& Hayt M.W.,1999 & Lal K. et al. 2006}and in the proper choice of implant size and angulation and this in turn helps to avoid injury of critical structures such as the mandibular canal or maxillary sinus {Ganz S.D,2001; Scaravilli MS, et al 2009& Naitoh et al. 2010}.

Moreover the CT scan allows the visualization of the scanned jaw bone in a series of cross sectional, axial and panoramic views .This makes the planning of implant placement more precise in relation to the bone and future prosthesis especially when the a radiographic template {scano-guide} is used during scanning{Lal K.et al. 2006& Rubio-Serrano M. et al 2008 }.However CT scan by itself is nothing but series of axial and coronal 2-D images and the clinician needs to integrate such images in his mind to gain the desired information in 3-D {Gillespie J.E. & Isherwood I.1986}.

Interactive software programs:

The present development of clinical computer applications allows the clinicians to obtain 3-D models to plan virtually real situations {Rubio-Serrano M. et al 2008}.

Interactive computer software is now increasingly used as a tool for implant diagnosis, planning and treatment execution. Firstly, it is used in connection with imaging techniques, such as computerized tomography (CT) or magnetic resonance imaging (MRI) { Hassfeld S, Mühling J 2001}. Secondly, it is used for the construction of surgical templates carrying the information necessary to transfer that planning to the mouth of the patient. In most of the cases, this procedure is based on stereolithographic models { Ewers R . et al 2005 & Ganz S.D. 2005 , Schneider D. et al 2009 }. There are different commercialized soft ware programs are available, such as: Implametric, SimPlant { Ganz S.D. 2005& Parel SM & Triplett RG 2004}, Nobel Guide {Rocci A et al. 2003}, med3D { Engelke W& Capobianco M. 2005}, etc. Most of the programs display an axial cut and a panoramic cut with multiple bucco-lingual cuts {parasagittal} and reformatted 3-D image {Parel SM & Triplett RG 2004}. In the 3D image, bony structures are visualized with the possibility of incorporating other anatomical structures or even soft tissues {Schneider D. et al 2009}.

Bone density

One of the good tools in the software programs is the ability to evaluate the bone density {quality} during the analysis of CT data. The importance of bone quality {density} for the success of dental implants is agreed on in the literature { Jemt T, Lekholm U 1995; Esposito M et al 1998; Shahlaie et al 2003 & Park et al 2008}.As suggested by Lindh et al.1996 Site-specific measurements are important, not only for a general prediction of treatment prognosis but also in the evaluation of how long of an interval between first- and second-stage surgical procedure and loading is needed { Friberg B et al 1991,1995a &1995b}. Moreover, to have accurate preoperative measurements of the bone density helps in avoiding the placement of the implants in the areas of poor quality {Norton M.R. and Gamble C. 2001& Shahlaie et al 2003}.

The strong correlation between the average CT number and the concentration of hydroxyapatite in bone is reported {Maki et al 1997}, and the quantitative CT in Hounsfield units {HU} are accepted as a valuable supplement to the subjective bone density classification defined by Lekholm and Zarb {1985}. The Hounsfield index is a standardized scale for reporting the reconstructed CT values. It is a measure of the attenuation coefficient which varies among different tissues, it is based on the density of air (-1000),water (0) and dense bone(1000){ Shapurian T. et al. 2006}. Misch CE {1993} stated that the bone density measurements using CT scan is more accurate than radiographic assessment. And he classified bones into 5 categories according to density: D1 bone had density above “1250 HU”; D2 = “850-1250′ HU”; D3 = “350-850 HU”; D4 = “150-350 HU”; and D5, below”150 HU”. For this, the use of CT scanning and interactive software programs is considered as a viable and accurate method to measure bone density {Norton M.R. and Gamble C. 2001& Shahlaie et al 2003}.

Recently, efforts in the oral imaging field have focused on developing tools that accurately and automatically measure bone density by measurements of x-ray absorption{ de Oliveira R. C. G. et al. 2008}. Thanks to such efforts, now the CT images in DICOM {Digital Imaging and Communications in Medicine} format contain the required data of bone density which enables the different software programs can measure it {Norton M.R. and Gamble C. 2001& Park et al 2008}.

Bone graft volume

Accurate evaluation of the 3-D bone volume before surgery is another advantage of the use of soft ware programs in the treatment planning in implant dentistry. The lack of enough bone volume frequently precludes the conventional implant placement. In this condition the bone volume needs to be improved by different augmentation techniques and /or materials {Esposito M. et al, 2008}.The detailed information about the needed bone volume before surgery is of much help in determining the best donor site { Krennmair G. et al 2006 & Verdugo F. et al 2009} and can help in estimating the amount and costs of the xenographic bone substitute required for the augmentation surgery{Clavero J.& Lundgren S. 2003}. Moreover, knowing the needed bone volume in advance helps in minimizing the duration of the surgery and this in turn minimizes the chances of complications and reduces the expenses for the patients {Cricchio G. & Lundgren S.2003}. The computerized tomography {CT} can produce series of accurate cross sectional images and by the aid of soft ware programs like Simplant {Materialise, Leuven, Belgium} the 3-D volume of area to be augmented can be calculated {Hatano N. et al. 2004& Krennmair G. et al. 2006}.

Flapless implant surgery:

Predictable flapless implant surgery is one of the fruits of the application of modern technology like CT scan, interactive software programs and CAD/CAM fabricated surgical guides {Sclar A.G. 2007}. Minimal invasive surgery techniques are applied to a wide variety of interventions. The main aim is to reduce the costs of the treatment and patient healing time {Rubio-Serrano M et al 2008& Valente F. et al 2009}.

The traditional implant protocol set by Branemark requires a duration of a few months for osseointegration of the endosseous implants before the connection of definitive dental prostheses {Adell R. et al 1981; Branemark PI 1983 & Lindquist LW et al 1996}. When compared with the surgical phases, implant prosthesis fabrication is relatively time consuming {Rodrigues AH et al, 2003}.

When implants are placed without flap elevation, both the amount of osseointegration and bone height around the implants are significantly greater than in implants placed with flap elevation. This enhancement is most probably due to the preservation of bone vascularization {Pennel B.M. et al 1967; Wilderman M.N et al. 1970& Jeong S-M et al 2007}. Moreover, the small sized punched mucosa lead to small, clean, closed wounds are known to heal quickly with little scar formation, whereas large open wounds heal slowly and with significant scarring{ Mathes S.J.,2006 & Lee D-H et al. 2009}.18 D.C. Sabiston and H.K. Lyerly, Textbook of previous termsurgery,next term Saunders, The biological basis of modern surgical practice. Philadelphia (1997) p. 207-20.

Recently, the use of flapless surgery for implant placement has become popular. This can be attributed to its numerous advantages that include improved patient comfort and healing, decreased surgical time, and the ability to resume normal hygiene procedures immediately following surgery. However, the flapless approach is only indicated when the surgeon is confident that the underlying osseous anatomy is ideal relative to the planned implant size and its 3-D position in the alveolus. If this is not the case; many problems may arise like: injury of the unseen vital structures, thermal damage secondary to inadequate irrigation during osteotomy preparation, malposed angle or depth of implant placement, and inability to appropriately contour osseous topography to facilitate restorative procedures {Sclar A.G. 2007& Van De Velde T. et al. 2007}. For this, the use of the conventional flapless implant placement should be limited to clinicians with advanced clinical experience and good surgical assessment {Sclar A.G. 2007}.

By no