Diagnosis for Dental Implant PDF

CHAPTER 2 DIAGNOSIS FOR DENTAL IMPLANT Initial workup for patient selection: The critical selection of patients and the critical application of endosteal dental implants are the two most important prerequisites for the treatment success that we’re all desire, LANNEY 1986. The three most basic princi...

CHAPTER 2 DIAGNOSIS FOR DENTAL IMPLANT Initial workup for patient selection: The critical selection of patients and the critical application of endosteal dental implants are the two most important prerequisites for the treatment success that we’re all desire, LANNEY 1986. The three most basic principles that apply to all medical treatment are particular importance for implant therapy: - Nihil nocere (“do not harm”), - evaluate risks and benefits, - avoid over treatment. A brief review of the patient’s general physical health: - is the patient’s cardiovascular & renal system stable? - does the patient have any bleeding disorders? - is the patient immunocompromised? - does the patient have an uncontrolled endocrine disorder (e.g. diabetes)? A screening oral examination: - does the patient have an adequate oral hygiene? - is there sufficient soft and hard tissues for placing & restoring implants? Radiographs of the implant sites: - Periapical radiograph for individual implant sites - Panoramic radiograph for overview of anatomical structures - Tomographies in case of anatomic proximities, surgical templates etc. Photographs: - Pre-operative Intraoral and extra oral photographs of the selected patient. Medical History: Absolute contraindications: Absolute contraindications to implant rehabilitation include recent myocardial infarction and cerebrovascular accident, valvular prosthesis surgery within 6 months, immunosuppression, bleeding disorders, active treatment of malignancy, drug abuse, psychiatric illness, as well as bisphosphonate therapy for more than 5 years. Any of these conditions bar elective oral surgery, and require judicious monitoring by the physician as well as the dental provider. (Hwang D, Wang HL.2006) Relative medical contraindications: Systemic conditions and habits influence dental implant survival to varying degrees. Illnesses that impair the normal healing cascade compromise surgical success. The mere presence of a disease, however, does not necessarily preclude implant therapy or affect significantly long-term outcomes. Certain disorders, when controlled improve implant survival rates. Relative contraindications include adolescence, osteoporosis, smoking, diabetes, positive interleukin-1 genotype, HIV positive patients, cardiovascular disease, and hypothyroidism. Temporary limiting contraindications: Acute inflammatory diseases and infections: - Influenza, bronchitis, gastroenteritis, sinusitis and inflammatory diseases of the urogenital tract Pregnancy: - Stress factors Pregnancy gingivitis Inability to take radiographs Inability to prescribe medication Temporary consumption of certain medications: - Anticoagulant and immunosuppressant drugs Physical and psychic stress situations: - Corporal conditions: physical disability - Psychosocial situations: unemployment, divorce and death of a family member Poor patient compliance: - Psychological or intellectual conditions modifying his co- operation Alcohol and drug abuse: - Unreliable co-operation and motivation, (poor oral hygiene) - Patients inadequately nourished, exhibiting a generally compromised immune response Neurosis, psychosis: - Complexity of psychological conditions, tendency to recur, (absolute contra-indications) Problem Patients: - Emotionally unstable patients - Treatment using the least invasive therapy to avoid subsequent conflict between the dentist and the patient General and nutritional conditions: - Cachetic and grossly obese patient (significant risk) - Age: biological situation more important than chronologic age Current medications: - Certain medications with their effect or their side effects can induce complications during the surgical procedure or long term difficulties (corticosteroids, immunosuppressive, long term antibiotic therapy); blood diluting drugs can cause bleeding in a very long time Metabolic disorders: - Juvenile diabetes type 1 (absolute contraindication) - Type 2 diabetes (relative contra indication) (ECKERT 1989, BOHLENDER 1988), - Major effects of hyperthyroidism including loss of physical (osteoporosis) and mental vigor Hematologic disorders: - Erythrocytes (anemia), (absolute contraindication) - Leukocytes (reduced host defence), (absolutecontra indication) - Blood clotting system (hemorrhagic diathesis), (absolute contra indication). Cardiac and circulatory diseases: - Surgery possible but associated with increased risk, - Absolute prerequisites: evaluation of circulatory parameters and knowledge of the cardiac disorder. Osseous metabolic disturbances: Systemic and local osseous disorders, (absolute contraindications), (osteomalacia, ostitis deferments, osteogenesis imperfecta) - Post menopausal osteoporosis (25 % of women over age 60): evaluation of the risk to benefit ratio - Collagen disorders: - Pathologic function of the immune system with inflammatory alterations of collagenous connective tissue (contra indications), (scleroderma, SJÖGREN syndrome, rheumatoid arthritis,) Dental implant as a potential bacterial focus: - High risk of bacteriaemia with patients presenting heart valve prosthesis or history of bacterial endocarditic - Alloplastic vascular replacements (cardiac bypass surgery, pacemaker,): not serious risks Dental History: During a conversation on the topic with the patient, it is important to consider the patient’s general and dental knowledge, motivation and compliance with the treatment being provided. This awareness leads the patient to clean the peri-implant area, especially during the initial stages of healing after placement. Anatomical factors that may complicate implant placement are: - Nasal or sinus floors, - Inferior alveolar nerve, - Roots of adjacent teeth that cannot be moved orthodontically. - Impacted teeth Others factors may also include: - Diseases of the oral mucosa (lichen planus, etc.) Uncontrolled periodontitis, especially aggressive forms Retained roots Inter arch distance: insufficient or too much implant crown ratio Intra oral contraindication: Unfavourable intermaxillary relationships: - Inadequate bone quantity - Problematic intermaxillary relationship: implants crown ratio Problematic occlusal and functional relationships: - Dysgnathia (gap between arches) - Functional or parafunctional disturbances: bruxism, Pathologic conditions in the alveolar bone: - Roots fragments, cysts, foreign bodies, granuloma, inflammatory reactions - Re-evaluation after appropriate treatment Radiation therapy in the jaw region: - Damage of cells and vascular elements in irradiated jaws Danger of osteoradionecrosis with chronic ulceration of the bone Pathologic alterations of oral mucosa: - Leukoplakia or lichen planus, (absolute contra-indications), - Stomatitis. Xerostomia: Age related saliva flow reduction (menopause), auto- immune disorders, long term drug therapies, - Reduced saliva flow does not exert a physiologic cleansing effect and so does not reduce sufficiently the bacteria (relative contraindication) - * Macroglossia: - Patients with long term partial or total edentulism that caused an enlarged tongue * Myxedema, *Acromegaly Unrestored teeth, poor oral hygiene: - Plaque retention, poor patient co-operation, bacterial risk. COMPREHENSIVE CLINICAL EXAMINATION: Extraoral clinical examination: - Facial asymmetries, - Soft / hard tissue pathology, - Temporomandibular joint disorders, Intraoral examination : Morphology of the alveolar ridges, intermaxillary relationship, condition of the oral mucosa, general condition of the remaining dentition, as well as level of oral hygiene are generally taken into consideration before placement of an implant, which can be subdivided into the following: - Dental caries, - Occlusal wear and patterns, - Restorations / prosthesis, - Pulpal diseases, - Cracked or fractured, - Mobility, - Occlusal habits, (bruxism,.etc), - Jaw relations (diagnostic casts): inter arch distance, - jaw relationships, tooth position and alignment. Periodontal or peri-implant tissues examination: - Pockets probing depths (6 per tooth or per implant), - Gingival recessions, - Disease activity (increasing in clinical attachment loss, bleeding on probing, suppuration), - Amount of inflammation, plaque, and / or calculus, - Color, contour, and consistency of gingival biotype, - Furcation involvements, - Levels of adjacent cementoenamel junctions to implant site, - Amount of keratinized gingiva, - Frenum pulls, - Depth of vestibule, - Width and height of osseous tissues (sounding, radiographs), - Thickness of gingiva, - Tooth mobility or migration. Evaluation of existing prosthesis: Inspection of the prosthesis that the patient may or may not be wearing can provide tips about special prosthetic problems, as well as the psyche of the patient. Evaluation of the intra and extra oral photographs: The importance of documenting and observing each tooth in a magnified image and surrounding area adds to the betterment of the treatment plan and maintenance phase. Evaluation of a radiograph: Prognosis of remaining teeth, proximity to vital structures, bone availability as well as the possible existence of any pathologic conditions. Evaluation of an articulated study casts: The exact measurement of mesiodistal space and intermaxillary arch space is more accurately performed on a cast than intraorally. Quantitative measurement of the amount of concavity in the alveolar ridge is needed for planning soft and hard tissue augmentation using the study casts. Indication for placement of implant: In early 1970’s, the edentulous, severely atrophied mandible represented to be one of main indication for implant supported prosthesis and in some situations it was considered to be the only indication. This is mainly because, the conventional complete dentures often proved to be unsatisfactory for patients with edentulous mandibles, whereas implant treatment achieved a significant improvement. The range of indications has increased in recent years; if the patient is healthy and the intraoral condition (bone availability) points toward successful osseointegration, implants can be indicated or to be the treatment of choice not only for edentulous and partially edentulous patients, but also for the replacement of a single tooth. Radiography: Pre-operative Radiography INTRA ORAL AND PANORAMIC RADIOGRAPHY: The radiographic technique of choice is the intra oral paralleling technique with projections perpendicular to the tangent of the dental arch in the areas of interest. The bisecting angle technique should be avoided because it distorts dimensions. When applied to the edentate regions: - The intra oral technique provides valuable information concerning the mesiodistal dimension of the region in which implants are considered and, thus about the number of implants that can be inserted. - Radiographs also provide information about the potentially available bone height relative to the mandibular canal, floor of the nose, mental foramen and floor of the maxillary sinus. - It can dimensionally determine cases of the implant treatment that cannot be performed due to lack of available bone volume unless bone augmentation procedures are performed. Panoramic radiography can provide information that is necessary to determine whether implant treatment may be contemplated however its lack of detail often prohibits a sufficiently accurate diagnosis of tooth related diseases. In panoramic radiographs: - Distortions are frequently found, above all concerning horizontal dimensions (TRONJE 1982). This makes panoramic images less well suited for accurate estimates of the amount of bone available in the mesiodistal direction, particularly in the anterior parts of the jaws. -- when anatomic conditions makes impossible to place in an intra oral films parallel to the vertical axis of the alveolar process, a better estimate of bone height can be made in panoramic radiographs. - It is important that due account is taken of the magnification in panoramic radiographs, as this can vary between panoramic units. It has been demonstrated recently that the use of templates with incorporated metal spheres of known diameter in situ when the radiograph is taken can effectively eliminate the distortion problems. The metal spheres appear radio-opaque in the final film; because their diameter is known, it is easy to calculate the true bone height (BEHNEKE 1986, SPIEKERMANN 1987). When implants will be inserted between the teeth, and the mental foramen, or between a tooth and the anterior border of the maxillary sinus, supplementary intra oral radiographs should always be obtained: - They should be taken with a direction of the X-ray beam perpendicular to the tangent of the alveolar arch. - Inaccurate horizontal angulation of the x-ray beam can easily make the distances of interest appear too small or, less frequently too large (GRÖNDAHL & al. 1996). An important objective of the preoperative radiographic evaluation of the implant patient is to determine the height and the width of the bone available for implant insertion. Ideally, the bone width should allow complete coverage of all implant threads 1mm – 2mm on both the buccal and the lingual sides. The available bone height must be estimated from the part of the alveolar bone in which a sufficient bone width is found to a site specific anatomic border in the vertical direction, e.g. the lower border of the nasal cavity, the lower border of the maxillary sinus, or the upper border of the mandibular canal. Sufficiently accurate estimations of bone width and height cannot be obtained without cross sectional tomography. To achieve ideal conditions for a successful integration of the implant with the surrounding bone, it is important that good images of the implant recipient site can be obtained during the diagnostic phase. The most important factor is the presence of a sufficient amount of cancellous bone ratio to compact bone 3:1 in which the implant can be anchored: - The compact bone at the marginal bone crest can provide stability of the marginal part of the implant. The cancellous can provide the cells and nourishment for the implant. - Stability in the anterior part of the mandible is obtained by anchoring the implant in a layer of cortical bone at the base of the mandible. - In the maxilla, the lower border of the nasal cavity or the maxillary sinus cannot provide the necessary ‘apical’ stability and hence the stability comes from the surrounding wall that is holding the implant in place. - If neither of these possibilities are at hand, stability of one of the surfaces of the implant can sometimes be achieved by placing it in a layer of buccal or more often lingual bone cortex and augmenting the missing wall. Often during the radiographic diagnosis stage a concavity is detected in the buccal surface, apically located to the cortical layer which makes it not suitable for anchoring: - A shorter implant can provide sufficient stability if the concavity is at the mid part, bone augmentation with intentional perforation of buccal plate of the bone is predictably performed instead of compromising the angulations of the implant. - A relatively narrow width of the jaw bone in combination with a thick, cortical marginal border may provide proper conditions for immediate implant stability and hence the stability comes from the surrounding wall that is holding the implant in place. - A narrow alveolar bone with a thin layer of compact bone at the alveolar crest often provides less than optimal conditions for implant treatment. Bone splitting prior to implant placement can maintain the 1mm-1.5mm cortical buccal bone. All the above situations should be analyzed with radiographic imaging. - The presence of thick trabeculae in the spongious bone can provide the necessary conditions for good primary stability (VAN DER STELT 1979, LINDH & al. 1996) - The trabecular pattern seen primarily reflects the conditions in the junctional area between compact and trabecular bone, - The presence of a trabecular pattern is no guarantee that bone trabeculae will be found in the interior part of the jaw bone; - The absence of such pattern strongly indicates a definitive absence of bone trabeculae. Radiographic measurements are neither so accurate nor so precise that they can be completely trusted (GRÖNDAHL & al. 1991, EKESTUBBE & GRÖNDAHL 1993, LINDH & al. 1996): - One must decrease the calculated distances by 1-2 mm; to avoid damages of the infra alveolar neurovascular bundle, a safety margin should be applied to the calculated distances between the marginal bone crest and the upper border of the mandibular canal; - Due accounts must also be taken of the fact that the drilling procedure which precedes the implant insertion goes.5mm – 1mm deeper than the implant itself. - One must also taken in account that the upper part of the implant cannot always be placed at the level of the marginal crest, e.g. in cases when an implant has to be placed buccal or lingual to the upper bone margin or when a narrow width of the marginal bone makes reduction of the bone height necessary. CROSS SECTIONAL TOMOGRAPHY: The horizontal dimension of an intended implant site can be determined from intra oral or panoramic radiographs. In curved parts of the dental arch, measurements in panoramic radiographs can be inaccurate due to distortions. Preliminary estimates of the bone can be made in intra oral radiographs, provided that a paralleling technique has been used, or in panoramic radiographs. Determination of actually available bone height is the best made in cross sectional tomograms in which the width of the jaw and also the bone can be determined and measured. Cross sectional tomography should be done perpendicular to the tangent of the dental arch and perpendicularly to a horizontal reference plane, the hard palate for maxillary examinations and the base of the mandible for mandibular examinations. To determine the distance between the mental foramen and an anteriorly positioned tooth, intra oral radiographs should be obtained with an X- ray beam direction perpendicular to the tangent of the dental arch. Cross sectional tomography in the mandible is needed to determine the distance between the marginal bone crest and the upper border of the mandibular canal as well as the presence of lingual concavities and the inclination of the alveolar process. The single implant case: The distance between opposing root surfaces is preferably measured in intra oral radiographs. Slight variations in patient positioning can make such a distance appear too small or too large in panoramic images. If tomography is considered necessarily, thin tomographic layers 1mm should be used to avoid disturbing ghost shadows. Tomography is recommended when a single implant is to be placed above the mandibular canal or any single implant where the available bone is in doubt. COMPUTED TOMOGRAPHY: Similar to tomographs, the exposures are made in single plane, with the help of a computer and special software that allows for multiplanar reformation of the image, planes of section in all three dimensions of space can be produced. The dentist has at his/her disposal cross-sectional panoramic and occlusal views of the actual osseous topography in 3D. Equipment from GENERAL ELECTRIC CORPORATION (DENTASCAN ®) employs the MSPA technique (maxilla-mandible shape pattern analysis). This provides transverse section images at 1 mm intervals from left to right around the entire dental arch in both mandible and maxilla. The other vital indication is to visualize and calculate the ratio between the cancellous bone and cortical for better treatment planning especially if bone augmentation procedures are indicated. Conebeem is a recent generation of CT (CBCT) which performed with patient sitting or standing in 30 seconds and equal radiation to a digital panoramic radiograph. Finding the (HU) housefield unit is also an additional information which a CT can provide. RISK FACTORS SUBJECT RISK: Cigarette Smoking: Cigarette smoking is a major preventable cause of human disease; it results in increased mortality and morbidity. (Around 50% of smokers died due to smoking related illnesses ;DOLL & al. 1994). Cigarette smoking is associated with impaired healing of surgical wounds (REES & al. 1984, SIANA & al. 1989, SILVERSTEIN 1992). Periodontal effects of cigarette smoking (TONETTI 1999): - Smokers present 3 to 7 times higher risk of developing periodontitis, - Smoking has been shown to explain up to 51% of the total attributable risk for periodontitis, - Smokers respond less well to periodontal therapy, - - The treatment associated decrease in the risk of periodontal disease progression seems to be more limited in time. BAIN & MOY 1993 observed that a significantly greater % of implants failures occurred in smokers than in non smokers: - Smokers had an overall implant failure rate of 11.3 %, - Non smokers presented a failure rate of 4.8 %. - While failures rates decreased with increasing implant length, the failure rate for each implant length was consistently higher in smokers than in non smokers. Cigarette smoking was associated with significantly higher levels of marginal bone loss (HAAS & al. 1996, LINDQUIST & al. 1996), and soft tissue inflammation (HAAS & al. 1996, WEYANT 1994). LINDQUIST & al. 1997: - The extent of marginal bone loss around osseointegrated implants has been associated with the number of cigarettes smoked, - Both smoking and oral hygiene are associated with marginal bone loss. A recent prospective investigation has evaluated the effect of peri operative smoking cessation protocol on short term implant survival (BAIN 1996): - the protocol involved patient information of the increased risks of implant failure among smokers and involved complete smoking cessation for 1 week before and 8 weeks after surgery; - the results indicated that the displayed short term implant failure rates similar to those who had never smoked, and significantly lower than among the smokers who did not follow the protocol; - This initial indication of the short term benefits of a smoking cessation protocol is highly suggestive of a possible causal relationship between smoking and implant failure. Osteopenia and Osteoporosis: Low bone density at the site of implant placement (type 4 bone) has been associated with increased risk of implant failure in retrospective (JAFFIN & al. 1991) and prospective (HUTTON & al. 1995) investigations. The latter investigation indicated that patients with low quantity and low density of bone were at highest risk for implant loss. An investigation indicated that the prevalence of implant sites with type 4 bone was twice as high among heavy smokers as among people who had never smoked or light smokers. Smoking might therefore produce its negative effects on implant survival both directly and via a possible effect on jaw bone density. Systemic osteoporosis has also been mentioned as a possible risk factor for lack of success with osseointegration (DAO et. 1993, ROBERTS et. 1992). Concerning osteopenia, it was demonstrated that implant placed in lower quantities of bone were at higher risk of failure (HUTTON & al. 1995). Indirect evidence to support this notion also comes from the recognition that shorter implants in the past higher failure rates than longer ones in a given time period. Diabetes: Uncontrolled diabetes has been shown to be a risk factor for periodontal disease (EMRICH & al. 1991, NELSON & al.1990). A 1 year report of implant survival in non insulin dependent diabetics indicated a 7.3 % failure rate. This seems to indicate that osseointegration can be obtained in the majority of diabetic patients. Nevertheless, the medium to long term prognosis of implants placed in these subjects is currently unknown. Medications: A medical and medication history has been associated with an increased risk of implant loss (WEYANT 1994). Few isolated reports, Ibandronate ( Boniva) 2.5 mg PO qd and Alendronate (Fosamax) 70mg PO qwk have associated implant failure with the assumption of anti osteoporosis drugs and Diphosphonate in particular (STARK & al. 1995). These reports should caution to clinicians with regards to the potential impact of medication whose mode of action might interfere with the physiology of the bone remodelling process. Cause of Tooth Loss and Persistent Periodontal Infection: A case report showing loss of the endosteal osseointegrated implant placed in the dentition of a subject affected with a rapidly progressive early onset form of a periodontal disease has suggested a possible relationship between the cause of tooth loss and an increased risk of implant disease leading to implant failure (MALMSTRÖM & al. 1990). The concept that implants may be affected by the periodontal conditions comes from two indirect lines of evidence: - Similar microflora colonizing teeth and implants in partially edentulous patients (MOMBELLI & al. 1995, PAPAIOANNOU & al. 1996); - Identification of a hyperinflammatory phenotype in partially edentulous patients with peri-implantitis lesions (SALCETTI & al. 1997). Inadequate Oral Hygiene: An increase of implant failure (VAN STEENBERGHE & al. 1993), and an increased prevalence of soft tissue problems (WEYANT 1994), have been reported in subjects with suboptimal levels of oral hygiene. Others observations are reporting an increased prevalence of complications following oral and periodontal surgery procedures in plaque infected dentitions (LINDQUIST & al. 1997), has also suggested a possible synergistic effect of inadequate oral hygiene and cigarette smoking in the determination of marginal bone loss around successfully integrated implants. Elderly Patients: Questions concerning limitations vis à vis dental implant for older patients are relatively easy to answer. The important concern is the biological age and not the chronological age. A good rule of thumb is that a patient should have a life expectancy of at least 5 years from the time of implantation. Young Patients: More difficult is the question concerning how early in life dental implants may be placed. Numerous authors have stated that implants should not be placed before the 15th to 16th year of life. This is based on the assumption that, for boys and girls, jaw growth is complete by this time. Clinical studies have shown a continuation of facial growth into the late teens for women and into the twenties for men (BJÖRG 1963, SILMAN 1964, HUNTER 1966, BISHARA & al. 1984). More recently, there has been an increase in the number of authors, who warn against placement of dental implants during the growth period (ÖDMAN & al. 1991, LEKHOLM 1993, LEDERMANN & al. 1994). STÖCKLI 1984 demonstrated that the distance between implants placed into a still growing osseous bed remained the same despite the fact that the bone increased in size. This observation can be explained when one considers that newly formed bone in the peri-implant area serves as an isolating tissue despite the histologically similar structure functional growth of the jaw bone itself. The primary task of the peri-implant bone is to stabilize and circumscribe the implant. A similar process in connective tissue is the scar formation, which likewise does not take part in functional growth. Some have offered that the assumption of the osseous prerequisite (cessation of growth) for the placement of dental implants is achieved after age of 15 or 16. However, especially in the esthetically sensitive anterior segment of the maxilla, this assumption must be tempered by the fact that no definitive correlation exists between chronologic patient age and completion of jaw growth. Even the consideration of a hand radiograph as an additional diagnostic aid for dental implantology has its limitations because the growth of bone in the jaw regions continues later than the long bones. If the treatment plan includes the option of dental implants in the anterior region of a young patient (before age 15 to 16): - Serious consideration should be given to the possibility of subsequent esthetic complications if implants are placed, versus the temporary use of a Maryland bridge; - The latter may, of course, be associated with resorption of the labial bony wall of the edentulous space. Implant Site: Substancial experimental evidence has indicated that different intra oral sites are associated with different rates of implant survival. It is currently unclear whether the observed differences can be explained, at least in part, by the insertion of shorter implants in the posterior regions of the jaws and / or by lower bone density in these regions. Encroachment to vital structures could also alter the survival rate. Implant Device: Several investigations have indicated that shorter devices seem to be lost more frequently than longer ones (BAHAT 1993, BUSER & al. 1997). This observation can be interpreted in 2 ways: - the shorter implants offer the smaller surfaces for implant bone contact and may therefore be more prone to biomechanical overload of the implant device, - and / or a marginal peri-implant infection spreading apically along a shorter implant may require less time to cause resorption of a critical portion of the established osseointegration lead to loss of the device. Differences in implant surface have also been associated with increased risk of implant loss: hydroxyapatite coated implants have been found to be at higher risk for failure in a large independent medium term investigation (WEYANT 1994). This finding is no longer observed anymore (et al. 2008) with recent improved HA coated surfaces. Clinical Significance: Knowledge of subject risk should assist the clinician with determining the prognosis for the individual case and thus with patient selection. Improved understanding of subject based on risk for periimplantitis and biomechanical overload combined with a careful preoperative assessment of implant based risk could be useful in determining number, location and type of implants as well as the design of the reconstruction.