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Home , Dental implant, Osseointegration

REVIEW ARTICLE

Implant Failure - Prosthodontist’s Eye View

Reddy Priyadarshini Department of , GSL Dental College, Lakshmi Puram, Rajahmundry - 533 104, Andhra Pradesh, India

Email for correspondence: [email protected]

ABSTRACT With the concept of , success of implants has drastically increased. This created awareness among the patients who wanted the edentulous site to be replaced with an . As said success and failure go hand in hand, failure after successful osseointegration of the implant results in psychological disturbance to the patient as well as the clinician, which adds additional procedures, duration, as well as cost. The present article gives a view over the prosthodontic considerations.

Key words: Classifications, evaluation, fractures, implant failures, osseointegration

INTRODUCTION tooth replacement using implant. With a predictably Over the decades, has emerged into a high success rates reported for implant-supported field with various scopes in treatment modalities. restorations, failures that require removal of One among them is implant dentistry, though implants do occur, which affects the clinician and evidence of use and success were reported since AD the patient. 600, the surge in implants for tooth replacement In the present scenario, where implant dentistry increased from middle of the 1900s.[1] is to be practiced through interdisciplinary is a prosthetic device made approach, there were cases where implant is placed, of alloplastic material(s) implanted into the oral and after osseointegration, the prosthodontist tissues beneath the mucosal or/and periosteal layer, is called for / placement. If and on/or within the to provide retention and any failure arises, then it is simply called the support for a fixed or removable ; prosthodontic failure. Is it really a failure due to a substance placed into or/and on the jaw bone the prosthesis and the prosthodontist? The present to support a fixed or removable dental prosthesis article briefs the prosthodontic considerations for (glossary of prosthodontic terms - 8).[2] implant failure. Implant failure is the inadequacy of host tissue CLASSIFICATION OF IMPLANT FAILURE to establish or maintain osseointegration. It is the Implant failures are classified based on the failure of the implant due to mechanical or biological time of failure, etiology, origin of infection, condition reasons.[3] Any prosthesis which does not serve the of failure, supporting tissue type, and according to purpose such as function, phonetics, and esthetics osseointegration concept. can be termed a failure.[4] According to Esposito .[5] Awareness regarding implants among the general population has increased to a level where 1. Biological failure: patients directly approach the asking for Early or primary - inadequacy of the host tissue to establish or to maintain osseointegration Quick Response Code Article Info: Late or secondary - failure to maintain the achieved doi: 10.5866/2018.10.100047 osseointegration.

Received: 02-01-2018 2. Iatrogenic failure - stable and well osseointegrated Revised: 25-01-2018 but cannot be loaded due to error in positioning Accepted: 07-02-2018 the implant and damage to underlying nerves. Available Online: 15-04-2018, 2017 (www. 3. Mechanical failure - implant fractures, fracture nacd.in)© NAD, 2017 - All rights reserved of the screws, and framework.

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According to Truhlar, Tonetti, and Schmid[6] •· At Stage II (With healing head and or abutment · Early failure - failure within 3 months of insertion) implant placement which may be due to altered •· After restoration. healing process. According to condition of failure (clinical · Late failure - after 3 months of implant and radiographic status) placement. •· Ailing implants - bone loss with deeper probing According to Askary[3] depth but stable at 3–4 months. According to aetiology. •· Failing implants - bone loss, increased probing depth, , and signs of FAILURES BECAUSE OF HOST FACTORS inflammation but no mobility •· Medical status - and any other •· Failed implants - clinical mobility, peri-implant bone diseases; uncontrolled diabetes. radiolucency, and dull sound when percussed. •· Habits - and parafunctional habits. •· Surviving implants. •· Oral status - poor maintenance, According to responsible personnel juvenile, and acute periodontitis, and irradiation •· Dentist (oral surgeon, prosthodontist, and therapy. periodontist) RESTORATIVE PROBLEMS •· Dental hygienist •· Excessive cantilever, pier abutments, no •· Laboratory technician passive fit, improper fit of the abutment, improper •· Patient. prosthetic design, and improper occlusal scheme, According to failure mode bending moments, connecting implants to natural •· Lack of osseointegration (usually mobility) dentition, premature loading, and excessive torquing •· Unacceptable esthetics are restorative problems that may lead to the implant •· Psychological problems. failures. According to supporting tissue type SURGICAL PLACEMENT •· problems (lack of keratinized tissues, •· Off-axis placement (severe angulation) inflammation, etc.) •· Lack of initial stabilization •· Bone loss (radiographic changes, etc.) •· Impaired healing and infection because of •· Both soft tissue and bone loss. improper flap design or others •· Excess heat generated during bone drills Heydenrijik .[4] - occurrence in time •· Inadequate irrigation •· Early failures - Osseointegration has never been •· Minimal space between implants established, thus representing an interference •· Placing the implant in immature bone-grafted sites with healing process. •· Contamination of the fixture before placement • Late failures - Osseointegration not maintained IMPLANT SELECTION implying processes involving loss of osseointegration •· Improper implant type in improper bone type. •· Soon late failures - Implants failing during the •· Length of the implant (too short, crown-implant 1st year of loading. ratio unfavorable) •· Delayed late - Failure’s implants failing in •· Diameter of the implant subsequent years. According to origin of infection CRITERIA TO EVALUATE THE FAILURE OF •· Peri-implantitis - infective process and bacterial AN IMPLANT[7] origin Schnitman and Schulman criteria (1979) •· Retrograde peri-implantitis - traumatic origin, non-infective, forces off the long axis, •· Mobility <1 mm in any direction premature, or excessive loading. •· Radiologically observed radiolucency graded, but no success criterion defined According to timing of failure •· Bone loss no greater than one-third of the •· Before Stage II (after surgery) vertical height of the bone

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•· Gingival inflammation amenable to treatment; •· Radiograph that does not demonstrate evidence absence of symptoms and infection, absence of peri-implant radiolucency of damage to adjacent teeth, absence of •· Bone loss that is <0.2 mm annually after the paresthesia and anesthesia or violation of the implant’s 1st year of service mandibular canal, , or floor of •· Individual implant performance that is the nasal passage characterized by an absence of persistent • Functional service for 5 years in 75% of patients. and/or irreversible signs and symptoms of Crainin, Silverbranch, Sher, and Salter pain, infections, necropathies, paresthesia, or Criteria (1982) violation of the mandibular canal •· In context of criteria mentioned a success rate •· In place 60 months or more of 85% at the end of a 5-year observation period •· Lack of significant evidence of cervical and 80% at the end of a 10-year observation as saucerization on radiographs a minimum criterion for success. •· Freedom from hemorrhage according to Muhleman’s index Esposito M, Hirish JM, and Lekholm Criteria [5] •· Lack of mobility (1998) •· Absence of pain or percussive tenderness •· Absence of mobility •· No pericervical granulomatosis or gingival •· Radiographic marginal bone loss of <1.5 mm hyperplasia during the 1st year •· No evidence of a widening peri-implant space •· <0.2 mm annually after the 1st year on radiograph •· Absence of pain or paresthesia. McKinney, Koth, and Steflik Criteria (1984) According to time period of failure - Jividen [8] Subjective criteria and Misch •· Adequate function •· Surgical failure •· Absence of discomfort •· Osseous healing failure •· Patient belief that esthetics and emotional and •· Early loading failure psychological attitudes is improved. •· Late implant failure Objective criteria •· Long-term implant failure. •· Good occlusal balance and vertical dimension EVALUATION OF IMPLANT FAILURE •· Bone loss no greater than one-third of the Clinical signs of failure vertical height of the implant, absence of symptoms, and functionally stable after 5 years •· During the early phase of healing, complications •· Gingival inflammation vulnerable to treatment such as swelling, fistulas, suppuration, early/ •· Mobility of <1 mm buccolingually, mesiodistally, late mucosal dehiscence’s, and osteomyelitis and vertically can occasionally be present which can lead to •· Absence of symptoms and infection associated disturbance in osseointegration process. The with the dental implant first sign of failure can be pain or discomfort •· Absence of damage to adjacent tooth or teeth associated with mobility. Mobility of the implant and their supporting structures indicates a fibrous union which clearly dictates •· Absence of paresthesia or violation of removal of implant. mandibular canal, maxillary sinus, or floor of Different types of mobility are as follows: nasal passage •· Rotation mobility •· Healthy collagenous tissue without •· Lateral or horizontal mobility polymorphonuclear infiltration. •· Axial or vertical mobility Success criterion Occasionally, clinically, discernible mobility •· Provides functional service for 5 years in 75% of can be present without distinct radiographic bone implant patients. changes. Thus, mobility can be considered the vital Albrektsson, Zarb, Worthington, sign of implant failure. and Erickson G Criteria (1986) Radiographic signs of failure •· Individual unattached implant that is immobile •· According to Alberktsson ., marginal bone loss of when tested clinically 1.5 mm during the 1st year and <0.2 mm yearly

Journal homepage: www. nacd. in Indian J Dent Adv 2018; 10(1): 47-52 Implant failure - Prosthodontist’s view Priyadarshini

can be considered as success criteria.[9,10] Whereas 2. Crown height space - It is measured from crest a thin perifixtural radiolucency surrounding the of the bone to occlusal plane in posteriors and to entire implant, with increased marginal bone incisal edge in anteriors.[13] Ideal crown height loss and absence of a direct bone-implant contact space for a fixed implant prosthesis is around indicating loss of stability, and an increased 8–12 mm, which includes the biologic width, marginal bone loss indicates a failed implant abutment height (screw retained or cemented), •· Percussion - Subdued sound on percussion occlusal material strength, esthetics, and hygiene is indicative of soft tissue encapsulation. considerations around abutment crowns.[10,13] A clear crystallization sound suggests good Increase in this crown height space increases the osseointegration. forces on cantilevered or angled load. Excessive stress can lead to crestal bone loss, screw Prosthodontic considerations for implant loosening, occlusal material fracture, prosthesis failure fracture, or attachment wear and fracture, and Prosthodontic evaluation begins before implant implant fixture fracture, thus implant failure. placement. Preimplant prosthodontic considerations 3. Masticatory dynamics - Muscle mass, gender, are a vital phase of overall treatment before implant exercise, diet, state of dentition, physical status surgery. influence the muscle strength, masticatory [10] Significant risk factor in implant dentistry is dynamics, and the maximum bite force. biomechanical stress. Its magnitude is directly 4. Arch position - Forces are more in the posterior molar region which are generated by the related to force. As a result, an increase in any masseter and the temporalis where the condyles dental force factor magnifies the risk of stress- being the fulcrum.[10] related complications.[10] 5. Opposing arch - Implant fixed prosthesis do not Patient force factors to be considered are benefit from proprioception as do the natural 1. Parafunction - , clenching, and tongue teeth. Bite forces increase by 4 times than the thrust. natural teeth. Highest forces are generated a. Even after successfully placing the implant with implant prosthesis.[14] fixture, early failure or late failure can Preimplant prosthodontic occur due to parafunction. These failures evaluation includes assessment of[10] are more in the maxillary arch compared to the mandibular due to the and Maxillary anterior tooth Lip lines also an increase in the moment of force.[11] position Maxillomandibular relations These conditions must be identified during Occlusal vertical Existing occlusion the early phases of treatment planning. dimension CHS b. Nadler classified causes of parafunction as Mandibular incisal edge Temporomandibular joint status Maxillary posterior plane Extraction of hopeless or follows:[12] Mandibular posterior guarded ‑ prognosis existing 1. Local factors - tooth form or occlusion plane teeth and soft tissue change as ulcerations or Existing prostheses pericoronitis Arch form 2. Systemic factors - epilepsy, cerebral Natural tooth adjacent to palsy, and drug-related dyskinesia implant site 3. Psychological - anxiety and emotional Soft tissue evaluation of tensions edentulous site 4. Occupational - professionals such as , athletes, precision workers, • Forces on implant - Implant and its component and musicians who developed altered can sustain the forces which are directed along oral habits the long axis, but they cannot sustain the off- 5. Involuntary - bracing of jaws such as axial forces as they create stress at the implant- [15,16] during lifting of heavy objects or sudden bone interface. stop while driving • Cantilever - Restoration of completely edentulous arch with a cantilever fixed 6. Voluntary - gum, pipe smoking, prosthesis, the length and width of the and bracing telephone between head implant fixture, quality of the bone, number and shoulder

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of implants, opposing occlusion, and anterior the force applied to the screw, and greater the and posterior spread of implants must be risk of screw loosening. Higher the hex height, considered.[15,16] the less stress applied to the screw, and a • Tripod effect - Greater the tripod, more the corresponding lower risk for abutment screw resistance to bending, implants placed in a loosening.[17,18] straight line in an edentulous arch, and minimal • Fatigue fractures - Based on the number of resistance to bending forces compared to those cycles and intensity of the force, materials placed in a tripod. undergo fatigue curve. Due to this continuous • Occlusal load on the cantilever, fulcrum line fatigue prosthesis, screw fractures are observed is established in distal-most implant where in fixed partial and complete fixed prosthesis. cantilever is pushed toward the tissue surface Abutment screws are usually larger in diameter, and the anterior implants have tension and therefore, fracture is less often. Metal occlusally, thus resulting in bending forces framework fractures have been reported in an along the fulcrum.[16] average of 3% of fixed complete and overdenture Crown-implant ratio - 1:1 ratio acceptable in restorations. Implant body fracture has the full-arch restorations as they provide tripod least incidence.[10,19] effect. In partially edentulous conditions, 1:2 • Esthetic complications are categorized as ratio is more preferable. pink‑tissue failures and white-tissue failure.[20-24] • Tooth and implant connection - Implant is firmly anchored to the bone and does not Pink‑tissue failures White‑tissue failures are exhibit any mobility, whereas tooth exhibits Facial recession related to the certain mobility due to periodontal Gingival asymmetry General form of the tooth attachment.[10] Hence, the restoration should Papillary deficiency The outline and volume of the Graying of the gingival clinical crown be completely implant supported rather than tissue Color (hue and value) connecting the implant to the tooth. Surface texture • Occlusal design - Narrow occlusal table and Translucency lingualized occlusion with lingual cusps Characterization of maxillary contact the central grooves of CONCLUSION mandibular are better to prevent bending forces. Lateral forces or off-axial forces result Failure of an implant is not due to one single in failure of the implant, so the forces should entity; it has various factors associated. To achieve be diverted along the long axis of the implant. any success, identifying the various causes of failure Thus, establishing centric contact over implants and dealing with the failure at an appropriate time and not lateral contact is important. is important. It was told, implant placed within Prosthetic complications - Impact of occlusal the bone in any position can integrate well. When overload on mechanical components[10] the esthetics and function of the prosthesis are affected, due to the position of the implant, this Screw loosening Attachment wear improperly positioned implant poses a task for Component fracture Attachment fracture the prosthodontist. Prevention of prosthodontic Implant body fracture Denture tooth fracture failure of an implant can be best achieved with Acrylic /porcelain Acrylic base fracture accurate diagnosis and treatment planning fracture Opposing prosthesis fracture through interdisciplinary approach and through a Framework fracture Esthetic complications better understanding about the and • Improper fit of the abutments and the fixture can the forces acting on the implant and the implant create constant tension and lead to abutment components. screw loosening or fracture. Greater the stress applied to the prosthesis, greater the risk of REFERENCES abutment screw loosening. Cantilevers also 1. Prashanti E, Sajjan S. Implant failures. Indian J Dent Res increase the risk of abutment screw loosening, 2011;22:446-53. as they increase the forces in direct relationship 2. Ferro KJ. The glossary of prosthodontic terms. J Prosthet to the length of the cantilever. Greater the Dent 2017;117:1-105. crown height attached to the abutment, greater 3. El Askary AS, Meffert RM, Griffin T. Why do dental

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