The implant failures are classified based on the causative factor and is sub-classified into the following:
1) Factors related to the patient - i.e., Host Factors.
2) Surgical Technique and Placement.
3) Selection of the implant for a particular patient.
4) Restorative Problems.
Now we will discuss each of these factors in detail.
Host Factors
These factors are very important and it is essential for the clinician to keep these in mind during the diagnosis and treatment planning stage in order to prevent these failures from occurring.
Medical status of the patient Conditions like osteoporosis, history of radiotherapy, use of bisphosphonates which can affect the success of the treatment should be considered before planning the treatment. Bone pathologic conditions like Paget's disease, fibrous dysplasia which lead to altered bone architecture are definitive contraindications for dental implant therapy.
Uncontrolled diabetes and other pathologies like bleeding disorders have to be carefully weighed before starting the treatment process in order to ensure predictable dental implant treatment. Therefore, the importance of a thorough medical evaluation and laboratory investigations to rule out any such pathology can not be overemphasized.
Habits
Smoking has been shown to predispose to poor bone quality by reduced vascularity.Therefore it is prudent not to accept heavy smokers as implant patients until and unless a strict smoking cessation protocol has been followed well before commencement of the treatment and the patient bone has been duly informed of the risks as smokers are twice as predisposed to failures than non smokers.Parafunctional Habits like bruxism and clenching create mechanical and biological problems due to overloading and are considered to be one of the most common cause of bone loss or lack of rigid fixation of the implant during the first year after implant placement. The condition needs to be identified during the diagnosis stage and emphasis should be placed on any tooth wear, fracture or crazing lines on the teeth, hypertonicity of masticatory musculature and features like accentuated antegonial notch on the panoramic radiograph. Though not an absolute contraindication,patients with parafunctional habits have to be treated with concern regarding the bio-mechanics and more number of implants used to improve stress distribution, as wide implants as the bone width allows should be used, delayed loading protocol should be followed, cantilevers should be eliminated, fewer occlusal contacts on lateral excursive movements in order to reduce the detrimental off axial loads, an occlusal splint as a nightguard should be used.
Oral Status of the Patient
It is imperative that the patient carry out a strict oral hygiene regimen as dental plaque is one of the main factors that leads to implant failure. The suprabony connective tissue fibres are oriented parallel to the implant surface, it is susceptible to plaque accumulation and bacterial ingress. This is compounded by the rough surface of the implant which influences bacterial colonization. Rougher surfaces like the Titanium plasma coated implants and Hydroxy apatite coated implants are more prone to bacterial colonization.
Localized Aggressive Periodontitis: It has been in literature that transmission of peridontopathic microorganisms from periodontitis sites to implant sites is likely to happen. It is therefore imperative that the patient is treated for periodontal disease prior to placement of implants
Irradiation and its Implication: The issues are the decreased salivary flow, liability for infection because of the decreased blood supply and the possibility of osteoradionecrosis. However, it is known that the survival rate of the implants in normal versus irradiated patients is not significantly different. The waiting period following irradiation before implant surgery can be done has been 3-6 months, 6 months and 12 months as per different authors. However, a six month period is suitable as after 6 months fibrosis is expected to begin in the irradiated tissues as a result of reduced cell reproducibility and progressive ischaemia. The use of hyperbaric oxygen has also been recommended to improve the healing capacity and to avoid soft tissue ulceration.
1) Factors related to the patient - i.e., Host Factors.
2) Surgical Technique and Placement.
3) Selection of the implant for a particular patient.
4) Restorative Problems.
Now we will discuss each of these factors in detail.
Host Factors
These factors are very important and it is essential for the clinician to keep these in mind during the diagnosis and treatment planning stage in order to prevent these failures from occurring.
Medical status of the patient Conditions like osteoporosis, history of radiotherapy, use of bisphosphonates which can affect the success of the treatment should be considered before planning the treatment. Bone pathologic conditions like Paget's disease, fibrous dysplasia which lead to altered bone architecture are definitive contraindications for dental implant therapy.
Uncontrolled diabetes and other pathologies like bleeding disorders have to be carefully weighed before starting the treatment process in order to ensure predictable dental implant treatment. Therefore, the importance of a thorough medical evaluation and laboratory investigations to rule out any such pathology can not be overemphasized.
Habits
Smoking has been shown to predispose to poor bone quality by reduced vascularity.Therefore it is prudent not to accept heavy smokers as implant patients until and unless a strict smoking cessation protocol has been followed well before commencement of the treatment and the patient bone has been duly informed of the risks as smokers are twice as predisposed to failures than non smokers.Parafunctional Habits like bruxism and clenching create mechanical and biological problems due to overloading and are considered to be one of the most common cause of bone loss or lack of rigid fixation of the implant during the first year after implant placement. The condition needs to be identified during the diagnosis stage and emphasis should be placed on any tooth wear, fracture or crazing lines on the teeth, hypertonicity of masticatory musculature and features like accentuated antegonial notch on the panoramic radiograph. Though not an absolute contraindication,patients with parafunctional habits have to be treated with concern regarding the bio-mechanics and more number of implants used to improve stress distribution, as wide implants as the bone width allows should be used, delayed loading protocol should be followed, cantilevers should be eliminated, fewer occlusal contacts on lateral excursive movements in order to reduce the detrimental off axial loads, an occlusal splint as a nightguard should be used.
Oral Status of the Patient
It is imperative that the patient carry out a strict oral hygiene regimen as dental plaque is one of the main factors that leads to implant failure. The suprabony connective tissue fibres are oriented parallel to the implant surface, it is susceptible to plaque accumulation and bacterial ingress. This is compounded by the rough surface of the implant which influences bacterial colonization. Rougher surfaces like the Titanium plasma coated implants and Hydroxy apatite coated implants are more prone to bacterial colonization.
Localized Aggressive Periodontitis: It has been in literature that transmission of peridontopathic microorganisms from periodontitis sites to implant sites is likely to happen. It is therefore imperative that the patient is treated for periodontal disease prior to placement of implants
Irradiation and its Implication: The issues are the decreased salivary flow, liability for infection because of the decreased blood supply and the possibility of osteoradionecrosis. However, it is known that the survival rate of the implants in normal versus irradiated patients is not significantly different. The waiting period following irradiation before implant surgery can be done has been 3-6 months, 6 months and 12 months as per different authors. However, a six month period is suitable as after 6 months fibrosis is expected to begin in the irradiated tissues as a result of reduced cell reproducibility and progressive ischaemia. The use of hyperbaric oxygen has also been recommended to improve the healing capacity and to avoid soft tissue ulceration.
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