Dental implants may be considered foranypatient inReasonable Healthwho desires the replacement of missingteeth and has enough bone in the areaorcan undergo a bone augmentationprocedure.
The survival of dental implantsmay beinfluenced by a number oflocal and systemic conditionsaffect the processof osseointegration directly
The bone and soft tissueresponse following dentalimplant placement iscontrolled by: Wound healing Biomechanics Mineral metabolism
Reasonable HealthASA Classification of Physical StatusP1: Normal, healthy patientP2: Patient with mild systemic disease with no functional limiltation,ie, a patient with a significant disease that is under good day to daycontrol,eg controlled hypertension, oral agents for DM, mild COPDP3: Patient with severe systemic disease with definite functionallimitations, ie, patient who is concerned with their health problemseach day, eg. aDM on Insulin, significant COPDP4: patient with severe systemic disease that is constant threat tolifeP5: Moribund patient who is not expected to survive 24hrsP6: Declared brain dead
Local and Systemic FactorsAgeIncreasing age has nosignificant effect onosseointegration or therate of crestal boneresorption around dentalimplantSchliephake H et al, Int J OMSImplants 1993
Local and Systemic Factors Patient ExpectationsRecent studies showed improved quality of life(comfort, function, speech, esthetics, self image)following dental implant therapy) Cibirka RM et al J ProstDent 1997
Local and Systemic FactorsSmoking Accelerates bone resorption arounddentalimplant Lindquist LW et al J Dent Res 1997 Greater risk of peri-implantitis espiciallythemaxilla Haas R et al J Prost Dent 1996 Interferes with osseointegration Kearns Get al Oral MedOral Path Oral Rad Endod1999 Failure Rate?
Smoking Systemic and local injury to the tissues Decrease tissue Oxygenation Nicotine: Decrease blood flowDecrease collagen depositionIncrease blood viscosityDelay wound healing
Smoking Increase failure rate 20% (Moy P et al Int J OMS implant2003) Advice on smoking Smoking cessation during the healingphaseimproved implant survival. Crews KM et al Gen Dent 1999 Strict OHI Submerged implants
Local and Systemic FactorsOSTEOPOROSIS A progressive systemic diseasecharacterized by lowbone mass and deterioration of bone massanddeterioration of bone tissue, leading tobone fragilityand fracture Long term maintenance of a rigid implantinterfacerequires continual bone remodeling.Roberts WE et al 1992Implant Dent. Osteoporosis can cause oral bone loss.Baxter and Fattore JProsthodont 1993
A Bianchi and F Sanfilippo Int PeriodonticsRestorativeDent 2002(The integration of missing teeth and therehabilitation ofthe functional integrity of thestomatognathic system,have a positive influence on the localmetabolic activityof the bone. Effective chewing; Diet) Oppose bone resorption along theresidual ridge VonWowern et al 1990 Bone tissue settles specifically around theloadedimplant. Steflik J Oral Implantol 1995 Increase density of bone around implant.Bianchi et al 1999
OSTEOPOROSIS Dental implants are not contraindicatedforpatient with osteoporosis, provided thattheirgeneral condition is strictly controlled. HRT.
Local and Systemic FactorsDIABETES MELLITUS Between 120-140 Million people sufferfrom D Mworldwide. 2025 It is expected to double. Well controlled D.M patients are suitablefor implantsurgery under antibiotic cover. Adell R1992 Controlled D M patients, 3 times likely todevelopimplant failure. Moy P et al 2003 Increased failure rate occurred during thefirst yearfollowing prosthetic loading. Fiorellini etal 2000
DIABETES MELLITUS Microvascular disease of the gingivaaffect bloodsupply and delay wound healing andincreaseinfection. Shernoff AF et al 1994 Tissue hyperglycemia affect the immunesystem,including neutrophill and lymphocytefunction,chemotaxis and phagocytosis
Local and Systemic FactorsCytotoxic chemotherapyChemotherapy following dental implanttherapy may havelittle effect on implant osseointegrationor survival.McDonald et al J Oral Implantol 1998Dental patients experience complicationsfollowingchemotherapy. Karr RA et al J ProsthetDent 1992Concurrent chemotherapy is associatedwith high failurerate and contraindicates the placement ofdentalimplants. Wolfaardt et al 1996
Cytotoxic chemotherapy Thorough and regular implant hygiene Delay dental implant placement followingchemotherapy until blood valuesnormalize
Local and Systemic FactorsBone marrow transplant Implant placement should be delayeduntilchemotherapy has ended and the marrowgrafthas taken
Steroids Ulcerative Colitis, Crohns disease, AsthmaOrgan transplant….. OsteoporosisDelayed wound healingSusceptibility to infection Success rate 88%. Peter et al J OMSImplant
Local and Systemic FactorsHIV Risk of peri-implantitis OHI and long term follow up Successful results in HIV positive patientsRajnazZW and Hochestter RL J Periodontol 1998
Local and Systemic Factors Hypohydrotic Ectodermal Dysplasia Scleroderma Sjogren Syndrome Multiple Myeloma Cleido-Cranial Dysplasia
Oral factorsPeriodontitis andperiapical lesions Past or presentperiodontal diseasecompromised implantsuvival. Cyril et al Int J OMS 2004 Comparable results. Cosci Fand Cosci B Compend Contin. Edn Dent1997
Oral factorsHead and Neck Radiotherapy Failure rate can range up to 30%Wermeister R et al JCraniomaxillofac Surg 1999 Risk of osteoradionecrosis, especiallywithirradiation dose above 50Gy. Most implant fail in the first 2 years.
Head and Neck RadiotherapyHypocellularity, Hypovascularity,Hypoxemia.XerostomiaMucositisMucosal Atrophy
6-12 month recovery period afterirradiation. Visch LL et al JIvest Surg 1994 Pre-surgical Hyperbaric Oxygen.Granstrom G et al 1992 Long term follow up Smoking Minimal reflection of periosteum Prolong healing period. Takeshita F JPeriodontol 1998 OHI
6-12 month recovery period afterirradiation. Visch LL et al JIvest Surg 1994 Pre-surgical Hyperbaric Oxygen.Granstrom G et al 1992 Long term follow up Smoking Minimal reflection of periosteum Prolong healing period. Takeshita F JPeriodontol 1998 OHI
Oral factorsOral Lichen PlanusErosive LP has been associated withdental implant loss,possibly because of altered capacity ofthe oralepithelium to adhere to the titaniumsurface, Lekholm U1997Reticular LP does not appear to influencedental implantsurvival. Lekholm U 1997Trauma due to implant surgery mayexacerbate OLPlesions. Katz J et al J Clin Periodontol1988
Oral Lichen Planus Patient should be warned of exacerbationofOLP Risk of failure in case of Erosive LP
Oral factorsOral Pre-malignantLesions The effect of dental implant onoral pre-malignant lesions isunknown. Sq C Carcinoma arise arounddental implant. Clapp C et al ArchOtolaryngol Head Neck Surg 1996 Radiotherapy
Diseases Relevant to SurgicalProcedureCardiac diseasesCardiomyopathyPericarditisCoronary heart diseaseRh heart disease Do not contribute to implant failure.Smith RA et al Int J OMSimplants 1992 Assess risk of endocarditis
It is the evaluation of all circumstances that can affect the outcome of a therapeutic intervention. In the case of dental implants the assessment is to identify variables that increase the risk of complications leading to implant loss.
Risk assessment should be performed: 1) Before placement of implants (designed to avoid high failure rates by identifying suitable candidates for implant treatment). 2) During the phase of implant placement and osseointegration (designed to identify and avoid technical issues that can affect implant survival). 3) During the phase of implant maintenance (designed to minimize failure by heading off problems). 4) After an implant has failed and been removed ( to identify the causes of failure ) .
It is an environmental, behavioral, or biological factor. If present directly increases the probability of a disease occurring and, if absent or removed, reduces that probability.
In the case of risk assessment for implant failure, risk factors can be broadly categorized as 1) Local risk factors. 2) Systemic risk factors. 3) Behavioral risk factors.
1. Taking thorough medical/dental histories.2. Complete examination of the prospective candidate for dental implants.
A comprehensive evaluation of the patient should contain a review of past dental history including: 1) Earlier periodontal treatment. 2) Reasons for tooth loss. 3) How extraction sockets were treated at the time of extraction. 4) History of increased susceptibility to infection.
5) Awareness of parafunctional habits such as clenching and grinding. 6) Evaluation of the patient’s socioeconomic status. 7) Dissatisfaction with earlier dental treatment may indicate an increased risk for complications during implant therapy. The comprehensive medical history should include past and present medications and any substance abuse.
A complete intraoral examination should be performed to determine the feasibility of placing implants in desired locations. This examination includes: 1. Oral hygiene status. 2. Periodontal status. 3. Jaw relationships. 4. Occlusion. 5. Signs of bruxism. 6. Temporomandibular joint conditions.
7. Endodontic lesions.8. Status of existing restorations.9. Presence of non-restored caries.10. Crown-root ratio.11. Interocclusal space.12. Available space for implants.13. Ridge morphology.14. Soft and hard tissue conditions.15. Prosthetic restorability.
Radiographic evaluation of the quality and quantity of available bone is required in order to determine the optimal site(s) for implant placement.
1. Periapical radiographs.2. Panoramic projections.3. Cross-sectional tomographic images give accurate estimation of bone height and width.
A comprehensive radiographic evaluation minimizes the risk of injuring vital anatomic structures during the surgical procedure and is also helpful in determining which cases require bone augmentation surgery before implants can be placed.
An evaluation of the quality and quantity of peri-implant soft tissues at the proposed implant site will help determine how closely this tissue will mimic the appearance of gingival tissue once the implant has been inserted.
The presence of keratinized mucosa around a dental implant is an important part of an esthetically successful dental implant. It is important to evaluate the patient’s perception of esthetics prior to implant placement especially in situations with compromised hard and soft tissues.
Diagnostic casts and intraoral photographs can be helpful in evaluating potential esthetic outcomes as well as in the overall treatment- planning process. In general, to minimize the risk of implant complications and failure, any diseases of the soft or hard oral tissues should be treated before implant therapy.
Post-operative infections increase the risk of early implant failure. It is important to perform implant surgeries with a strict hygiene protocol to minimize bacterial contamination of the surgcial site.
The incidence of post-operative infection associated with implant placement is only about 1% (Powell et al. 2005), some clinicians attempt to reduce this risk by prescribing pre-operative systemic antibiotics (Dent et al. 1997; Laskin et al. 2000). In addition, the results of several case-control studies indicate that there is no advantage in using antibiotics in conjunction with implant placement (Gynther et al. 1998; Morris et al. 2004; Powell et al. 2005).
Surgical techniques that are designed to avoid unnecessary tissue damage should be used. Thermal damage to bone can be caused during the drilling sequence if dull drills are used or if osteotomy is performed without using enough liquid coolant.
Post-insertion stability lowers the risk of implant complications or failure. The presence of good-quality bone with a sufficient amount of cortical bone at the implant site is desirable to achieve this objective.
In situations where there are less than optimal bone conditions. (thin cortect, low trabecular density), increased initial stability can still be established by using implants with rough surfaces, parallel walls, and optimal height and width.
Anatomic structures that are at risk of damage during the placement of implants include: Nerves, Blood vessels, Floor of the mouth, Nasal cavity, maxillary sinuses, Adjacent teeth.
It is important to remember that the drills used for osteotomies penetrate further than the depth indicators on the drills. In certain situations radiographic indicator methods should be performed during surgery to help determine direction of the implant and its proximity to vital structures.
For implants that are to be placed in the mandible, the distance from the edentulous alveolar crest to the upper border of the inferior alveolar canal should be assessed from cross-sectional tomographic radiographs.
The safety zone between the tip of the implant and the border of the canal should be at least 1-2 mm. Patients with compromised vertical bone dimension can sometimes be treated by placing multiple shorter implants of optimal width followed by splinting the prosthetic crowns together during the restorative phase of therapy.
The position of the mental formen should be identified and located when implant surgeries in the premolar and molar areas of the mandible are performed. In some situations a loop of the nerve can be found to extend mesially.
In one report the anterior loop of the mental neurovascular bundle extended mesially from 1.1 - 3.3 mm and a safety zone of 4 mm was recommended to avoid damaging the nerve during implant placement (Kuzmanovic et al.2003)
When placing an implant in the anterior part of the maxilla the size and location of the incisive papilla need to be determined. In addition, it must be established if there is enough bone in the area to place an implant or if the area needs to be grafted.
Anatomic concavities are frequently found on the lingual side of the mandible. It is important to avoid perforating the lingual plate during preparation of the implant site since perforations in this location can result in extensive and even life-threatening bleeding (Bruggenkate et al. 1993)
A safe way of performing surgery in this area is to reflect a lingual flap at least to a level corresponding to the length of the implant to be placed.
Poor oral hygiene and microbial biofilms are important etiologic factors leading to the development of peri-implant infections and implant loss. Therefore any risk assessment for implant survival should include an evaluation of the patient’s ability to perform oral hygiene procedures.
There are several reasons to believe that untreated or incompletely treated periodontitis increases the risk for implant failure. 1) There are case reports that suggest an association (Malmstrom et al. 1990, Fardal et al. 1999)
2) A similar subgingival microbiota has been found in pockets around teeth and implants with similar probing depths.3) Evidence exists that periodontal pockets might serve as reservoirs of pathogens that hypothetically can be transmitted from teeth to implants.
Peri-implant infections are caused by multiple microorganisms living on the implant surface in a biofilm. Peri-implant infections are not simply caused by Gram-negative anaerobic bacteria. This group of bacteria is important, but yeasts and Gram-positive bacteria as Micromonas micros and Staphylococcus species are often implicated in peri-implant infections.
Subgingival sites are the natural or preferred habitat of a diverse group of oral microorganisms. In an interesting study of 15 patients, Devides and Franco (2006) sampled mucosa-associated biofilms of edentulous sites with paper points and analyzed the specimens using polymerase chain reaction (PCR) methods to detect certain periodontal pathogens.
At the edentulous sites Aggregatibacter actinomycetemcomitans was detected in 13.3% of subjects, Prevotella intermedia was detected in 46.7% of subjects, and Prophyromonas gingivalis was not detected. Six months after placement of endosteal implants at the same sites, subgingival plaque samples taken from around the implants were positive for A. actinomycetemcomitans in 73.3% of subjects, Pr. Intermedia in 53.3% of subjects, and P. gingivatis in 53.3% of subjects.
None of the implants showed any clinical signs of either failure or peri-implantitis. These results indicate that healthy subgingival sites around implants are readily colonized by periodontal pathogens without any development of clinically detectable disease.
It is important to remember that the microbiota adjacent to failing implants will differ depending on the cause of the failure. For example, the microbiota associated with implants failing because of traumatic loads was different to that found around implants failing because of infection.
There are several reports that the survival rate of implants is decreased when the patient has a history of periodontitis. Patients who have had periodontitis might also be more susceptible to peri-implant infections.
However, this is clearly not always the case since it has also been demonstrated that periodontally compromised patients who have lost a considerable amount of alveolar bone can be successfully treated with dental implants based on post- insertion implant maintenance program.
The presence of untreated or unsufficiently treated endodontic infections adjacent to the site of implant placement can adversely affect the outcome. There are numerous reports of retrograde peri-implantitis in which it is hypothesized that a periapical infection on a tooth spreads to an adjacent implant.
It is clear that implants can be quite successful when placed in patients who are in their eighth and ninth decades of life. Several reports indicate that there is not a statistically significant relationship between age of the patient and implant failure.
However, a thorough risk-assessment process involves evaluation of multiple possible risk factors. It is possible that some older patients might have been excluded for medical reasons. Older individuals included were healthy enough to be good candidates for implant placement.
A potential problem associated with the placement of dental implants in still-growing children and adolescents is the possibility of interfering with growth patterns of the jaws. Osseointegrated implants in growing jaws behave like ankylosed teeth in that they do not erupt and the surrounding alveolar housing remains underdeveloped.
It is highly recommended that implants not be placed until craniofacial growth has almost complete.
Cigarette smoking is often identified as a statistically significant risk factor for implant failure. The reasons that smokers are more susceptible to both periodontitis and peri- implantitis, but usually involve impairment of innate and adaptive immune responses and interference with wound healing.
Smoking is such a strong risk factor for implant failure that some clinicians highly recommend smoking-cessation protocols as part of the treatment plan for implant patients.
Bisphosphonates are drugs used for the treatment of osteoporosis. These drugs are potent inhibitors of osteoclast activaty, have a high affinity for hydroxyapatite and have a very long half-life. An uncommon complication associated with the use of bisphosphonates is the increased risk of developing osteonecrosis of the jaws (ONJ) after implant placement.
Since bisphosphonates tightly bind to hydroxyapatite and have a very long half-life, it is likely that the length of time a patient has been taking oral bisphosphonates is important in determining the level of risk. In general, it is not recommended that implants be placed in patients who have been on the drug for more than 3 years.
It has been suggested by some that prolonged use of bisphosphonates is a contraindcation to implant placement. It is important to remember that bone- remodeling processes are severly inhibited in patients who have been chronically taking oral bisphosphonates for osteoporosis. Because of this such patients are poor candidates for bone-grafting procedures and sinus lift operations.
Gingival enlargement has been reported around dental implants in individuals taking either phenytoin or a calcium-channel antagonist. When there is significant gingival enlargement around teeth or implants, oral hygiene and maintenance procedures can become quite difficult.
Antimitotic drugs used as chemotherapy for oral cancer might affect wound healing and suppress certain components of the immune system, it is important to know if these drugs interfere with osseintegration and success of dental implants.
It has also been reported that some cancer patients who received cytotoxic antineoplastic drugs experienced infections around existing transmucosal or endosteal dental implants (Karr et al. 1992). Patients who are receiving cancer chemotherapy should have thorough periodontal and implant maintenance care to minimize the development of adverse events.
Patients who have blood-coagulation disorders or are taking high doses of anticoagulants are at an elevated risk of post-operative bleeding problems after implant surgery.
In such patients, local bleeding after the placement of dental implants can usually be well controlled by conventional hemostatic methods. The risk of developing life threatening bleeding or bleeding that cannot be controlled by using local measures following placement of dental implants is so low so no need to stop oral anticoagulant therapy.
Corticosteroids can interfere with wound healing by blocking key inflammatory events needed for satisfactory repair. In addition, through their immunosuppressive effects on lymphocytes, they can increase the rate of post-operative infections.
In the early years of the AIDS epidemic placement of dental implants was ill advised since affected patients developed major life- threatening oral infections. With the advent of effective HAART (highly active anti-retroviral therapy) regimens, most HIV-positive patients who take their medications live for many years without developing severe opportunistic infections.
Low T-helper (CD4) cell counts (i.e.<200/L) do not appear to predict increased susceptibility to intraoral wound infections or elevated failure rates of dental implants (Achong et al. 2006). Although more studies are needed, it appears that it is safe to place dental implants if the patient’s HIV disease is under medical control.
Patients who have received radiation to the head and neck as part of the treatment for malignancies are at an increased risk of developing osteoradionecrosis (ORN). Implant failure rates of up to 40% have been reported in patients who have had a history of radiation therapy.
It has been recommended that oral surgical procedures in patients at risk of ORN be performed in conjunction with hyperbaric oxygen (HBO) therapy. From the perspective of risk- assessment procedures for implant placement, patients who have a history of irradiation to the jaws should be considered at high risk or implant failure and HBO interventions will probably lower that risk.
In the risk evaluation of diabetics it is important to establish the level of metabolic control over the last 90 days is a blood test for glycosylated hemoglobin (HbA1C). Normal values for a non diabetic or a diabetic under good metabolic control are HbA1C 6-6.5% and fasting blood glucose (110 mg/dl ).
Diabetics with HbA1C values of ≥8% are under poor control and have an elevated risk of encountering wound healing problems and infection if dental implants are placed.
Osteoporosis is a skeletal conditionscharacterized by low bone mineral.There are multiple case reports thatconclude that osteoporosis alone is not asignificant risk factor for implant failure (Daoet al. 1993; Freiberg 1994; Fujimoto etal.1996; Freiberg et al. 2001).
Implants placed in individuals withosteoporosis appear to successfully Osseointegrate and can be retained for years.However, in cases of secondaryosteoporosis there are often accompanyingillnesses or conditions that increase the riskof implant failure (e.g. poorly controlleddiabetes mellitus, corticosteroidmedications).
Long-term success of dental implants requires that the patient is able to comply with the recommended post- insertion maintenance procedures required for long-term survival and success of implants.
Since poor oral hygiene is a documented risk factor associated with failure of implants, it is critically important that patients understand this and are taught the skills necessary to perform plaque removal on a daily basis.
In addition, since patient-performed oral hygiene does not adequately remove disrupt dental plaque biofilms at subgingival locations, periodic maintenance visits are needed. It is recommended that these visits be at 3- month intervals. The patient’s compliance with the recommended maintenance schedule is a major key to long-term success.
Patients who have addictions to alcohol and drugs are usually poor candidates for dental implants. Since the success of implant therapy requires a considerable amount of patient cooperation at all stages of care, individuals with substance-abuse problems should receive prosthetic care that does not depend on implants.
In general, Patients who have severe mental health problems or exhibit psychotic behavior are not good candidates for dental implants. The cooperation needed for successful implant therapy is missing. However, people with medically controlled mental health problems, such as depression, can be successfully treated with implants.
It is important that the practitioner determine if the information they tried to convey was understood. One of the best ways to do this is to convey the information in easily understood (nontechnical) language and in small increments. Patients who understand what is being done are usually quite cooperative and this cooperation leads to the increased probability of successful therapeutic outcomes.
Daily self-care (oral hygiene) and adherence to a maintenance-recall schedule is absolutely required for long- term success. This is best discussed to the patient at the consultation visit.
An effective way to reduce the risk of implant complications and failure is to stress the importance of the patient’s role as and active participant in the overall therapeutic program. Long-term success of both periodontal and implant therapy depends on an effective partnership between the patient and practitioner.
1. A Key part of implant therapy is the risk- assessment process that includes thorough medical and dental histories, a complete clinical examination, and an appropriate radiographic survey.2. The presence of one risk factor alone is usually insufficient to cause the adverse outcome. It is the combination of multiple risk factors that the has clinical importance.
3. To minimize the risk of implant complication clinicians can use a number of technical procedures, such as adhering to a strict hygienic surgical protocol, performing the osteotomies with sharp drills, achieving early implant stability, and avoiding damage to vital anatomic structures during surgery.4. Any endodontic, periodontal, and other oral infections be treated prior to implant placement.
5. Existing evidence does not support the routine use of pre-operative systemic antibiotics in implant therapy.6. Most of the systemic risk factors for implant complications are those that increase the patient’s susceptibility to infections or those that interfere with wound healing.