Lesson 7 Clinical Evaluation of the Implant Patient PDF

Clinical Evaluation of the Implant Patient Diagnostic Imaging for the Implant Patient Clinical Evaluation of the Implant Patient CONTENT Introduction Case Types and Indications Risk Factors and Contraindications Post treatment Evaluation Conclusion INTRODUCTION Dental implants are primarily used to...

Clinical Evaluation of the Implant Patient Diagnostic Imaging for the Implant Patient Clinical Evaluation of the Implant Patient CONTENT Introduction Case Types and Indications Risk Factors and Contraindications Post treatment Evaluation Conclusion INTRODUCTION Dental implants are primarily used to replace teeth in a partial or complete edentulous patient or to retain removable prostheses. The ultimate goal of dental implant therapy is to satisfy the patient's desire to replace one or more missing teeth in an aesthetic, secure, functional, and long-lasting manner. To achieve this goal, clinicians must accurately diagnose the dentoalveolar condition, as well as the overall mental and physical well-being of the patient. Local evaluation of potential jaw sites for implant placement (e.g., measuring available alveolar bone height, width, and spatial relationship) Prosthetic restorability are essential considerations in determining whether an implant(s) is possible. Making as assessment of the patient and determining whether that patient is a good candidate for implants is an equally important part of the evaluation process. Along with, the patient evaluation includes identifying factors that might increase the risk of failure or the possibility of complications, as well as determining whether the patient's expectations are reasonable. Perry R. Klokkevold, David L. Cochran,2017 Case Types and Indications 1. Complete Edentulous Patients 2. Partially Edentulous Patients Multiple Teeth Single Tooth Complete Edentulous Patients These patients can be effectively restored, both aesthetically and functionally— with an implant assisted removable prosthesis, or an implant-supported fixed prosthesis. ----used five to six implants in the anterior area of the mandible or the maxilla to support a fixed, hybrid prosthesis. -----The design is a denture-like complete arch of teeth attached to a substructure (metal framework), which in turn is attached to the implants with cylindrical titanium abutments Another implant-supported design used to restore an edentulous arch is the ceramicmetal fixed bridge (makes its appearance similar to that of natural teeth.) Both hybrid and ceramic-metal implant supported fixed prostheses provide very little lip support and thus may not be indicated for patients who have lost significant alveolar dimension. More problematic for maxillary reconstructions because lip support is more critical in the upper arch. some patients, the lack of a complete seal (i.e., spaces under the framework) allows air to escape during speech, thus creating phonetic problems. Depending on the volume of existing bone, the jaw relationship, the amount of lip support, and phonetics, some patients may not be able to be rehabilitated with an implant-supported fixed prosthesis. For these patients, a removable, complete-denture type of prosthesis is a better choice because it provides a flange extension that can be adjusted and contoured to support the lip, and there are no spaces for unwanted air escape during speech. This type of prosthesis can be retained and stabilized by two or more implants in the anterior region of the maxilla or mandible. Separate attachments on each individual implant to clips or other attachments that connect to a bar, which splints the implants together. Advantages Stability of the implant-retained overdenture shows increased retention and stability over conventional complete dentures is an important advantage for denture wearers. Additionally, implant-supported prostheses are thought to lessen the amount of alveolar bone loss associated with longterm use of removable prostheses (force bear directly on the alveolar ridges) Partially Edentulous Patients Multiple Teeth Partially edentulous patients with multiple missing teeth represent another viable treatment population for osseointegrated implants, but the remaining natural dentition (occlusal schemes, periodontal health status, spatial relationships, and aesthetics) introduces additional challenges for successful rehabilitation.(Lekholm U et al.,1994) The primary challenge with partially edentulous cases is an underestimation of the importance of treatment planning for implant-retained restorations with an adequate number of implants to withstand occlusal loads. Multiunit fixed restorations in the posterior jaw are more likely to experience complications or failures when they are inadequately supported in terms of the number of implants, quality of bone, or strength of the implant material. Better treatment planning with the use of an adequate number and size of implants, particularly in areas of poor-quality bone, has solved many of these problems. Single Tooth Patients with a missing single tooth (anterior or posterior) represent another type of patient who benefits greatly from the success and predictability of endosseous dental implants The greatest challenges to overcome with the single-tooth implant restorations were screw loosening and implant or component fracture mainly in posterior area. Because of the increased potential to generate forces in the posterior area, the implants, components, and screws often failed., can be managed by with the use of wider diameter implants and internal fixation of components. Wide-diameter implants resists tipping forces and thus reduces screw Loosening and also provides greater strength and resistance to fracture as a result of increased wall thickness (i.e., the thickness of the implant between the inner screw thread and the outer screw thread). Aesthetic Considerations Anterior single-tooth implants present an aesthetic concern for patients The prominence and occlusal relationship of existing teeth, the thickness and health of periodontal tissues, and the patient's own psychological perception of aesthetics all play a role in the aesthetic challenge of the case. Cases with good bone volume, bone height, and tissue thickness can be predictable in terms of achieving satisfactory aesthetic results Achieving aesthetic results for patients with less-than-ideal tissue qualities poses difficult challenges for the restorative and surgical team.(Beumer J 3rd et al, 1995) Replacing a single tooth with an implant-supported crown in a patient with a high smile line, compromised or thin periodontium, inadequate hard or soft tissues, and high expectations is probably one of the most difficult challenges in implant dentistry and should not be attempted by novice clinicians. Perry R. Klokkevold, David L. Cochran,2017 Pretreatment Evaluation A comprehensive evaluation is indicated for any patient who is being considered for dental implant therapy. The evaluation should assess ---- All aspects of the patient's current health status, including a review the patient's past medical history, medications, and medical treatments. Patients should be questioned about parafunctional habits, such as clenching or grinding teeth. Any substance use or abuse, including tobacco, alcohol, and drugs. The assessment should also include an evaluation of the patient's motivations, level of understanding, compliance, and overall behavior An intraoral and radiographic examination must be done to determine whether it is possible to place implant(s) in the desired location(s) Properly mounted diagnostic study models and intraoral clinical photographs are useful parts of the clinical examination and treatment-planning process to aid in the assessment of spatial and occlusal relationships. Once the data collection is completed, the clinician will be able to determine whether implant therapy is possible, practical, and indicated for the patient An organized, systematic history and examination is essential to obtaining an accurate diagnosis and creating a treatment plan that is appropriate for the patient. A thoughtful and well-executed evaluation can also reveal deficiencies and indicate what additional surgical procedures may be necessary to accomplish the desired goals of therapy (e.g., localized ridge augmentation, sinus bone augmentation). Perry R. Klokkevold, David L. Cochran,2017 Chief Complaint The patient's chief concern, desires for treatment, and vision of the successful outcome must be taken into consideration. The patient will measure implant success according to his or her personal criteria. The overall comfort and function of the implant restoration are often the most important factors, but satisfaction with the appearance of the final restoration will also influence the patient's perception of success. Furthermore, patient satisfaction may be influenced simply by the impact that the treatment has on the patient's perceived quality of life. Patients will evaluate for themselves whether the treatment helped them to eat better, look better, or feel better about themselves. With this goal in mind, it is often helpful and advisable to invite patients to bring their spouses or family members to the consultation and treatmentplanning visits to add an independent “trusted” observer to the discussion of treatment options. Ultimately, it is the clinician's responsibility to determine if the patient has realistic expectations for the outcome of therapy and to educate the patient about realistic outcomes for each treatment option. Perry R. Klokkevold, David L. Cochran,2017 Medical History A thorough medical history is required for any patient in need of dental treatment, regardless of whether implants are part of the plan. The patient's health history should be reviewed for any condition that might put the patient at risk for adverse reactions or complications.. Any disorder that may impair the normal wound-healing process, especially as it relates to bone metabolism, should be carefully considered as a possible risk factor or contraindication to implant therapy. Appropriate laboratory tests (e.g., coagulation tests for a patient receiving anticoagulant therapy) should be requested to evaluate further any conditions that may affect the patient's ability to undergo the planned surgical and restorative procedures safely and effectively. If any questions remain about the patient's health status, a medical clearance for surgery should be obtained from the patient's treating physician. Dental History Ø History of recurrent or frequent abscesses, which may indicate a susceptibility to infections or diabetes? Ø Does the patient have many restorations? ØHow compliant has the patient been with previous dental recommendations? Ø What are the patient's current oral hygiene practices? If a patient reports numerous problems and difficulties with past dental care, including a history of dissatisfaction with past treatment, the patient may have similar difficulties with implant therapy. It is essential to identify past problems and to elucidate any contributing factors. The clinician must also assess the patient's dental knowledge and understanding of the proposed treatment, as well as the patient's attitude and motivation toward implants. Intraoral Examination Ø To assess the current health and condition of existing teeth, ØTo evaluate the condition of the oral hard and soft tissues. ØTo find out any pathologic conditions present in any of the hard or soft tissues in the maxillofacial region. ØAll oral lesions, especially infections, should be diagnosed and appropriately treated before implant therapy. ØTo find out patient's habits, level of oral hygiene, overall dental and periodontal health, occlusion, jaw relationship, temporomandibular joint condition, and ability to open wide After a thorough intraoral examination, the clinician can Ø Evaluate potential implant sites. ØTo measure the available space in the bone for the placement of implants and in the dental space for prosthetic tooth replacement. ØThe mesial-distal and buccal-lingual dimensions of edentulous spaces. ØThe orientation or tilt of adjacent teeth and their roots should be noted as well.. For these conditions- orthodontic tooth movement may be indicated.. Ultimately, edentulous areas need to be precisely measured using diagnostic study models and imaging techniques to determine whether space is available and whether adequate bone volume exists to replace missing teeth with implants and implant restorations. Diagnostic Study Models Mounted study models are an excellent means of assessing potential sites for dental implants. Properly articulated models with diagnostic wax-up of the proposed restorations allow the clinician to evaluate the available space and to determine potential limitations of the planned treatment This is particularly useful when multiple teeth are to be replaced with implants or when a malocclusion is present. Hard Tissue Evaluation The amount of available bone is the next criterion to evaluate. A visual examination can immediately identify deficient areas whereas other areas that appear to have good ridge width will require further evaluation. Clinical examination of the jawbone consists of palpation to feel for anatomic defects and variations in the jaw anatomy, such as concavities and undercuts. If desired, it is possible with local anesthesia to probe through the soft tissue (intraoral bone mapping) to assess the thickness of the soft tissues and measure the bone dimensions at the proposed surgical site. Soft Tissue Evaluation Evaluation of the quality, quantity, and location of soft tissue present in the anticipated implant site helps to anticipate the type of tissue that will surround the implant(s) after treatment is completed (keratinized vs. nonkeratinized mucosa). Areas with minimal or no keratinized mucosa may be augmented with gingival or connective tissue grafts. Other soft tissue concerns, such as frenum attachments that pull on the gingival margin, should be thoroughly evaluated as well. Radiographic Examination Radiographic assessment of the quantity, quality, and location of available alveolar bone in potential implant sites ultimately determines whether q A patient is a candidate for implants q If a particular implant site needs bone augmentation. qPeriapical radiographs, panoramic projections, and cross-sectional imaging, can help identify vital structures such as the floor of the nasal cavity, maxillary sinus, mandibular canal, and mental foramen. Risk Factors and Contraindications For implant success and predictability, it is imperative for clinicians to recognize risk factors and contraindications to implant therapy so that problems can be minimized and patients can be accurately informed about risks before initiating treatment. Contraindications for the use of dental implants, although relatively few and often not well defined, do exist. Some conditions are probably best described as “risk factors” rather than “contraindications” to treatment because implants can be successful in almost all patients; implants may be less predictable in some situations, and this distinction should be recognized. Ultimately, it is the clinician's responsibility with the patient to make decisions as to when implant therapy is not indicated. Perry R. Klokkevold, David L. Cochran.2017 DIABETES Diabetes and peri-implantitis Retrospective study of Turkyilmaz ,2010 showed no evidence of diminished clinical success 1 year after implantation, defined by no bleeding on probing, no pathological probing depth, and a marginal bone loss of 0.3 ± 0.1 mm in a population of type II diabetics. The results in the prospective study of Gomez-Moreno, 2014 found that elevated HbA1c causes more bone resorption after 3 years. The bleeding on probing is more often in the poorly controlled population, but the probing depth is not increased. They concluded that implant therapies for diabetic patients can be predictable, providing these patients fall within controlled ranges of glycemia over time, assessed by monitoring HbA1c levels. Aguilar-Salvatierra ,2015, started to evaluate 2 years after insertion of dental implant and found that the number of patients suffering from peri-implant inflammation increases with elevated HbA1c values. The population was divided into well-controlled (HbA1c 6–8 %), moderately controlled (HbA1c 8–10 %), and poorly controlled (HbA1c >10 %), but there was no healthy control. They concluded that patients with diabetes can receive implant-based treatments with immediate loading safely, providing they present moderate HbA1c values.. Diabetes and implant survival Naujokat et al , 2016 in a systematic review mentioned 18 publications with data. Short period study covers 7 studies with observation time up to 1 year (6 prospective, 1 retrospective studies) Longer periods study included 4 prospective, 1 cross-sectional, and 6 retrospective studies. In the short-time group, 5 of the studies had a healthy control group The result for implant survival in diabetics is 100 to 96.4 %, which does not differ from the healthy control (Dowell et al, 2007, Alsaadi et al, 2007, Oates et al, 2014, Erdogan et al ,2014, Ghiraldini et al, 2015) The 2 studies without control group report a 100 % survival rate 4 months and 1 year after implantation [Turkyilmaz et al, 2010, Khandelwal et al, 2011]. The time periods in the long-time group differ from 1 year up to 20 years and are very heterogeneous Among 4 prospective, 6 retrospective, and 1 cross-sectional study, Seven studies compared the diabetic survival rates to healthy population, and results are equivocal. Survival rates of diabetics are similar to healthy control: 95.1 vs. 97 %, 97.2 vs. 95 %, 92 vs. 93.2 %, and 97 vs. 98.8 % [Morris et al,2000 , Anner et al 2010, Busenlechner et al. 2014]. On the other hand, there are 2 studies reporting relative risk for implant failure in diabetic patients elevated to 4.8 and 2.75, respectively [Daubert et al, 2015, Moy et al , 2005]. Studies without a healthy control present survival rates from 100 to 86 % [AguilarSalvatierra, et al, 2015], 97.3 and 94.4 % after 1 and 5 years [Peled, et al , 2003], and 91 to 88 % after 5 years [Olson et al, 2006], which are comparable to survival rates in healthy individuals. There was a large improvement in implant survival in the type II diabetic patients when chlorhexidine (CHX) (95.6 %, 4.4 % failures) was used at the time of implant placement, as compared to when CHX was not used (86.5 %, 13.5 % failures)(Naujokat et al, 2016) This difference in survival (9.1 %) was large enough to be considered clinically significant but was not found in the non-type II diabetic patient. For the non-diabetic group, survival increased only slightly when CHX was used (94.3 %, 5.7 % failures), compared to when CHX was not used (91.8 %, 8.2 % failures) [Olson et al, 2000]. ACTIVE CANCER THERAPY Both ionizing radiation and chemotherapy disrupt host defense mechanisms and hematopoiesis. In 3% to 35% of patients who undergo head and neck radiation, spontaneous and traumatic osteoradionecrosis ensues.(Marx RE, Johnson RP,1987) Mucositis and xerostomia resulting from radiation damage to mucosa and salivary glands, respectively, contribute also to a poor oral environment. Cytotoxic anticancer drugs induce rapid granulocytopenia, followed by thrombocytopenia. Myelosuppression occurs often from a multiple drug regimen. In addition to bone marrow toxicity and immunosuppression, anticancer agents cause gastrointestinal toxicity and skin reactions. PSYCHIATRIC DISORDERS In general, any type of psychological abnormality can be considered a contraindication to dental implant treatment because of the patient's uncooperativeness, lack of understanding, or behavioral problems. Physiologically, there is no reason to suspect that implants could not become osseointegrated in these patients. However, the patient's ability to tolerate the number and type of treatment appointments required for implant placement, restoration, and maintenance could be problematic. All psychological conditions have the potential to be absolute contraindications to implant treatment depending on the severity of the condition. The exception might be individuals who demonstrate good cooperative behavior with only mild psychological or mental impairment. The clinician should take great care before accepting a mentally or psychologically impaired individual for treatment with implants. BISPHOSPHONATE TREATMENT Bisphosphonate related osteonecrosis of the jaw (BRONJ) which was first published in the literature in 2003 is a severe side effect of bisphosphonate therapy [Marx RE J Oral Maxillofac Surg. 2003 Sep; 61(9):1115-7). Patients may be considered to have BRONJ if they have all of the following criteria. Current or previous treatment with a bisphosphonate Exposed bone in the maxillofacial region that has persisted for more than eight weeks No history of radiation therapy to the jaws. The prevalence and incidence remains uncertain. In general, the risk of BRONJ is between 1 in 10,000 and 1 in 100,000 but may increase to 1 in 300 after an oral surgical procedure. Intravenous administration leads to a higher drug exposure than the oral route, osteonecrosis related to oral bisphosphonate therapy is less common than that of related to intravenous forms such as zolendronate which is also more potent than oral bisphosphonates.(Ruggiero SL, et al 2009) This higher incidence of alendronate associated osteonecrosis of the jaw may be related to the frequent presciription of alendronate, or can be explained by its dose, potency, half-time, and absorption related factors --- Marx RE et al,2007 As oral bisphosphonates are less bio-available than intravenous formulations, they are used for long terms. Longer duration (for more than two years) has been associated with an increased risk of oral BRONJ. Otto S et al 2011. Dental implant therapy, as well as other surgical procedures, should be avoided in individuals who have been treated with intravenous (IV) bisphosphonate therapy and carefully considered with caution in patients treated with oral bisphosphonate therapy, particularly those with a history of more than 3 years of use. OSTEOPOROSIS Osteoporosis is a condition of universal reduction in bone mass in which resorption overtakes deposition, with no other abnormality. An examination of dental clinical studies on this osteoporosis reveals little effect of this disease on implant success.. Friberg et al 2001, placed 70 implants in the jaws of 14 patients with osteoporosis. This group achieved 97% success in both maxilla and mandible after 3-year followup. Taking the aforementioned reports into consideration, osteoporosis alone does not affect implant success SMOKING Nicotine attenuates red blood cell, fibroblast, and macrophage proliferation, increases platelet adhesion, and induces vasoconstriction via the release of epinephrine; this leads to a lack of perfusion and compromised healing. In addition, smoking promotes expression of inflammatory mediators (e.g., tumor necrosis factor- and PGE2), and impairs polymorphonuclear neutrophil chemotaxis, phagocytosis, and oxidative burst mechanisms. It also increases matrix metalloproteinase production (e.g., collagenase and elastase) by polymorphonuclear neutrophils. Retrospective analysis of 2194 implants placed in 540 subjects and found that failures occurred in 11% in smokers versus 5% in nonsmokers, a significant difference. The maxilla showed the greatest failure disparity between smokers and nonsmokers: 18% versus 7%, respectively. (Bain CA, Moy PK,1993) De Bruyn and Collaert, 1994, also described a negative impact of smoking on implants in a retrospective study of 452 fixtures in 117 patients; the failure rate in the maxilla 3-36 months after loading was 9% in smokers and 1% in nonsmokers. With no mandibular differences. Bain and Moy,1993, suggested a protocol without reliance on research-based data, hypothesized that stopping smoking 1 week prior to surgery would allow reversal of platelet adhesion, blood viscosity, and short-term effects of nicotine. In order to allow osteoblastic bone healing and adequate osseointegration to occur, they recommended tobacco abstinence until 8 weeks after fixture placement. In 1996, Bain, performed a prospective investigation on 223 implants in 78 patients. The group of subjects that followed a smoking cessation protocol exhibited a lower failure rate (12%) than the group that continued to smoke (38%). Weyant,1994, did not find a correlation between implant failure and tobacco use, but smoking appeared to increase the frequency of peri-implant soft tissue complications. A retrospective study by Minsk et al 1996 in 380 patients with 1262 implants also showed no relationship. Kumar et al,2002 looked at initial osseointegration before loading in 461 patients with 1183 surface-modified ITI SLA implants. In their retrospective study, they found successes of over 98% in both smokers and nonsmokers. The maxilla and mandible did not differ statistically with respect to failures. Nonsmokers and smokers did not exhibit variation in bone quality. Even Bain et al,2002 observed that surface-modified implants may resist effects of smoking. In a metaanalysis of 2274 dual acid-etched Osseotite implants (Biomet, Inc., Warsaw, IN), they found 3-year cumulative successes of 98.4% in nonsmokers and 98.7% in smokers. Machine-surface fixtures failed more often, but no success differences occurred between nonsmokers (92.8%) and smokers (93.5%) for these implants either. HUMAN IMMUNODEFICIENCY VIRUS Patients with an immuno compromising disease, such as human immunodeficiency virus (HIV) infection or acquired immunodeficiency syndrome (AIDS), are not good candidates for implants when their immune system is seriously impaired. Patients with very low or undetectable viral loads and normal (T cell counts) immune function may be candidates for implant therapy Without the presence of severe immuno suppression or bleeding disorders, HIV status does not lower implant success. Harrison et al, 2002 conducted a prospective, blind, controlled study on wound infection and orthopedic implants in HIV-positive and negative subjects. With no preoperative contamination, the incidence of wound infection failed to differ between patient groups. In regard to intraoral implants, Fielding et al,1990 presented successful osseointegration and function after 4 years in HIV-positive patients with CD4 counts of 200 cells/mm3 at the UCLA Symposium on Implants in the Partially Edentulous Patient. A case report demonstrated 18-month functional success of an immediate dental implant in an HIV-positive patient with CD4 counts less than 200 cells/mm3; a regimen of amoxicillin was given postoperatively.---- Rajnay et al, 1998 Post treatment Evaluation Periodic post treatment examination of implants, the retained prosthesis, and the condition of the surrounding peri-implant tissue are important components of successful treatment. Several parameters are available to evaluate the condition of the prosthesis, the stability of the implants, and the health of surrounding periimplant tissues after implant integration and prosthetic restoration. Intraoral radiographs should be taken at the time of placement (baseline), at the time of abutment connection (to confirm seating and serve as another baseline), at the time of final restoration delivery (loading), and subsequently to monitor marginal or periimplant bone changes. Conclusion Today, clinicians are able to predictably replace missing teeth with endosseous dental implants. Whether missing a single tooth, several teeth, or all teeth, many patients can be candidates for dental implant therapy. It is important for clinicians to recognize factors that influence implant success. In addition to the quantity, quality, and location of available bone, the patient's health, risk factors, and contraindications must be assessed. Patients should be informed about risk factors and provided with treatment options both with and without dental implants. Periodic evaluation, good oral hygiene, and regular maintenance are important aspects of care for the long-term success and the prevention of complications with dental implants. Diagnostic Imaging for the Implant Patient CONTENT Introduction Standard Projections Cross-Sectional Imaging Interactive “Simulation” Software Programs Patient Evaluation Clinical Selection of Diagnostic Imaging Conclusion Introduction Comprehensive and accurate radiographic assessment is a crucial aspect of dental implant treatment planning to evaluate bone quality, quantity, and anatomic structures in relation to the proposed implant sites. Traditionally, implant clinicians have relied on two-dimensional conventional radiograph modalities in implant dentistry, with the discovery of computed tomography (3D) a new era in all phases of the radiographic imaging survey of implant patients has become available.. Goal of radiographic imaging in implant dentistry is---To acquire the most practical and comprehensive information that can be used for the various phases of implant treatment. The implant team must assess each individual patient on which imaging modality should be used, and the decision should be based on sound and practical information. Phase 1 Imaging in implant dentistry Phase 1 is termed presurgical implant imaging---- involves all past radiologic examinations and new radiologic surveys to assist the implant team in determining the patient’s final comprehensive treatment plan. The objectives of this phase of imaging include all necessary surgical and prosthetic information to determine---- The quantity and quality of bone Identification of vital structures Proposed implant sites Presence or absence of disease. Phase 2 Imaging in implant dentistry Phase 2 is termed the surgical and intraoperative implant imaging phase Focused on assisting in the surgical and prosthetic intervention of the patient. The objectives of this phase of imaging are to evaluate---- The surgery sites during and immediately after surgery, Assist in the ideal position and orientation of dental implants, Ensure that abutment position and final prosthesis fabrication are correct Phase 3 Imaging in implant dentistry Phase 3 is termed the post prosthetic implant imaging. This phase commences just after the prosthesis placement and continues indefinitely. The objectives of this phase of imaging are to access the long-term maintenance, integration, and function of the implants, which includes the evaluation of the implant complex and surrounding crestal bone levels. Types of Imaging Modalities---A)two-dimensional imaging techniques Periapical radiography Panoramic radiography Occlusal radiography Three dimensional imaging techniques CT CBCT Interactive CT Three dimensional imagine techniques are quantitatively accurate, and three-dimensional models of the patient’s anatomy can be derived from the image data and used to produce stereo lithographic surgical guides and prosthetic frameworks Periapical Radiography The paralleling technique is generally preferred in implant dentistry because of less distortion and magnification. Direct exposure projections do not use intensifying screens, so intraoral radiographs offer the highest detail and spatial resolution of all radiographic modalities One of the most significant recent advances in dental radiology is the advent of digital technology. Film is replaced by a sensor that collects the data. The analog information interpreted by specialized software, and an image is formulated on a computer monitor. The resultant image can be modified (in various ways, such as gray scale, brightness, contrast, and inversion.) Compared with conventional radiographs, the most current digital systems have significantly less radiation (50%-65% approx)(Wenzel A, Grondahl H-G:,1995) with superior resolution.(Van der Stelt PF,2005) Advantages of Digital Intraoral Radiograph Øvery low radiation dose, Øimages have high resolution and can be modified in various ways. ØColor images may be formed for enhancement of evaluation and density readings. ØEnsuring accurate measurements.( Most computer software programs are now available to allow for calibration of magnified images) Disadvantages Distortion and magnification Minimal site evaluation Difficulty in film placement Technique sensitive Lack of cross-sectional imaging In phase 1 and 2 imagine cases to evaluate---§Small edentulous spaces, § Alignment and orientation of the implant during surgery §Confirmation that the implant is not invading an adjacent tooth root or mandibular canal during surgery are major benefits of periapical images. Abutment and Prosthetic Component Imaging When evaluating for transfer impressions along with two-piece abutment component placement, radiographs should be taken to verify complete seating. A slight angulation may allow a slight gap to remain unnoticed. In Post prosthetic Imaging (Phase 3 imagine ) Act as a baseline for future evaluation of component fit verification and for marginal bone level evaluation. May be used to verify the absence of cement (in cement retained crown) In recall and maintenance Imaging Follow-up or recall radiographs should be taken after 1 year of functional loading and yearly for the first 3 years. (Borg et al 2000) Multiple studies have shown that in the first year, marginal bone loss ( upto1.2 mm) and a higher rate of failure are seen. Occlusal Radiography Advantages Evaluation for pathology (sialiths) Limitations Does not reveal true buccolingual width in mandible Difficulty in positioning Indications None Panoramic Radiographs Panoramic radiographs are often used in the evaluation of the implant patient because they offer several advantages over other modalities. Truhlar et al, 1993. Panoramic radiographs deliver low radiation doses ( Effective Dose 20μSv) to provide a broad picture of both arches and thus allow----- Assessment of longer edentulous spans Angulations of existing teeth and occlusal plane Assessment of Important anatomy in implant treatment planning (such as the maxillary sinus, nasal cavity, mental foramen, and mandibular canal) Limitations Distortions inherent in the panoramic system Errors in patient positioning Does not demonstrate bone quality Misleading measurements because of magnification (approx 25%) No spatial relationship between structures Because of magnification and distortion errors, panoramic radiographs should not be used for detailed measurements of proposed implant sites. Computed Tomography The CT scan was invented by Sir Godfrey Hounsfield, an electrical engineer, in 1972. In dentistry, CT scanners were introduced in the 1990s and replaced two dimensional radiographic modalities. Typical dental views reconstructed from a MSCT scan include a scout view as well as axial , panoramic , and cross-sectional views of the jaws. Appropriate axial slices through the alveolar ridge of interest are selected as scout views. Computed Tomography Advantages Negligible magnification Relatively high-contrast image(the ability to distinguish two objects with small density differences) Various views Three-dimensional bone models Cross-referencing Limitations CT scanning is the significantly higher radiation (Effective Dose 920μSv) delivered to the patient Cost Cone-Beam Computed Tomography With the U.S. Food and Drug Administration’s approval of cone-beam technology, there exists the ability to provide more accurate diagnostic images along with a fraction of the radiation exposure with conventional CT and adherence to the ALARA principle.(Winter A, Pollack A,2005) field of view (FOV) An important feature of the various CBCT units is the field of view (FOV) describing the extent of the imaged volume. CBCT units are typically categorized as large FOV (greater than 15 cm), medium FOV (8 to 15 cm), and limited FOV systems (less than 8 cm). Large FOV units image a more extensive anatomic area, deliver a higher radiation exposure to the patient, and produce lower-resolution images. Conversely, limited FOV units image a small area of the face, deliver less radiation, and produce a higher-resolution image. Interactive “Simulation” Software Programs Implant treatment planning can be greatly enhanced by the use of specialized software In addition to measuring the quantity and quality of bone in potential implant sites, these programs use CT (MSCT or CBCT) scan data to simulate placement of implant and restorations. The length, width, angulations, and position of implants can be “simulated” in the desired positions and evaluated relative to other structures in three dimensions In cases of alveolar ridge deficiency or defects, or when sinus bone augmentation is indicated, the additional bone volume needed can be evaluated and quantified. The restoration of the implants can also be simulated and the distribution of mechanical forces onto the implant and adjacent bone predicted. Software programs specialized in implant treatment planning, such as SIM/Plant (Materialise/Columbia Scientific, Glen Burnie, Maryland), can acquire information directly from CBCT or CT scan data. InVivo5 planning software (Anatomage, San Jose, California) acquires data directly from CBCT or CT scan DICOM (Digital Imaging and Communications in Medicine) files without the need for reformatting. Indications for Computed Tomography–Guided Surgical Guides Surgical guides are very helpful in the precision and accuracy of implant placement. With surgical guides patient and treatment planning time increased and additional expense along with radiation exposure, which may outweigh the clinical benefits in certain cases. Some of the most common indications include--- The clinician’s early learning curve Proximity to vital anatomic structures Implant position that is crucial to the planned restoration Multiple implants in an esthetic region. Preimplant Evaluation: Diagnosis and Treatment Planning The first part of the preimplant evaluation is the assessment of the edentulous area in question for bone quantity and quality. Most proprietary software available today allows the implant dentist to evaluate the area of interest in multiple reconstructions in many different planes, including crosssection, axial, panoramic, sagittal, and three dimensional. From these reconstructions, a series of interactive tools is available, including measurement tools, bone density, angulation (restorative spaces), virtual teeth, and vital structure outlining (inferior alveolar nerve). Preimplant Evaluation: Site Evaluation with Implants After the quantity and quality of bone are evaluated, special software programs allow the implant dentist to actively place implants in areas of interest and allow for selection- Implant brand Type Dimensions along with prosthetic abutments that are selected from special libraries. These features allow for the placement of multiple implants that are precisely parallel, thus allowing for fabrication of a surgical template to be used for the surgical placement of the implants. if the implant needs to be placed at an angle, the angle can easily be determined and the final abutment selected even before the surgery. Immediate Loading Prostheses The newest technological advancement in CT-guided surgery is the fabrication of a provisional prosthesis that is immediately inserted at the time of surgery. After the virtual treatment plan is created by the implant team, computer-generated stereolithographic surgical guides are fabricated by the manufacturer from the virtual treatment plan. A dental laboratory then uses the fabricated surgical guides and mounted study casts to interim or final prostheses to be inserted after implant placement. Some software companies have allowed for the fabrication of provisional and final restorations to be completed from the Pre surgical workup. Clinical Selection of Diagnostic Imaging Screening Radiographs The American Academy of Oral and Maxillofacial Radiology,2000, recommends panoramic radiography as the initial evaluation of the dental implant patient, supplemented with periapical radiographs as needed. Cross-Sectional Imaging The American Academy of Oral and Maxillofacial Radiology , 2000, recommends that radiographic examination of any potential implant site should include cross-sectional imaging orthogonal to the site of interest. Fabrication of Radiographic and Surgical Guides Intraoperative and Postoperative Radiographic Assessment Conclusion Many radiographic projections are available for the evaluation of implant placement, each with advantages and disadvantages. The clinician must follow sequential steps in patient evaluation, and radiography is an essential diagnostic tool for implant design and successful treatment of the implant patient. Selection of appropriate radiographic modalities will provide the maximum diagnostic information, help avoid unwanted complications, and maximize treatment outcomes while delivering an “as low as reasonably achievable” radiation dose to the patient.