Dental Implant Failures

Dental implant failures can be biologic, mechanical, or esthetic, occurring when the implant no longer functions as intended. Early failures often stem from surgical or biologic issues like poor osseointegration or infection, while late failures are commonly linked to technical or mechanical complications. Esthetic failures affect appearance and patient satisfaction, sometimes developing over time. Accurate diagnosis involves clinical, radiographic, and patient-reported assessments. Effective prevention relies on thorough planning, precise surgery, careful restoration, and ongoing maintenance. This review categorizes implant failures into surgical, restorative, and esthetic phases for a clearer clinical understanding.

Key points

•
Dental implant failures can occur due to biologic, mechanical, and technical factors.
•
Surgical failures can be due to errors in diagnosing and treatment planning, or in the surgical procedure.
•
Failure in osseointegration may be due to factors such as the patient’s underlying systemic condition, poor oral hygiene, and habits.
•
Mechanical failures, such as screw fracture, framework fracture, and veneer chipping, can be due to functional overload, and improper angulation of the implant.
•
Factors affecting patient satisfaction regarding esthetics are considered a failure. A thorough patient evaluation, precise surgical planning, and regular maintenance are essential to minimize failure.

Abbreviations

PFM	porcelain fused to metal
PRO	patient-reported outcome

Introduction

Dental implants have undergone evolutionary changes in terms of newer materials, surgical techniques, and implant designs. A dental implant is considered to have failed when it cannot carry out its intended function. The failure can be biologic, mechanical, or esthetic. Understanding the causes and management of this failure is essential for clinicians to ensure long-term success and patient satisfaction. Surgical failure can be related to surgical errors or biologic complications, such as lack of osseointegration, periimplantitis, and injury to nerve or underlying systemic factors. Early failures may warrant implant removal and reimplantation after proper site preparation. On the contrary, long-term implant failures can be due to technical or mechanical factors. Esthetic failures impact the appearance and patient satisfaction of the implant restorations. Implant failures can be identified through subjective, clinical, and radiographic examination. The management includes non-surgical interventions, occlusal adjustments, and implant removal in case of failure of osseointegration. Preventive strategies to minimize implant failure include proper planning, meticulous surgical procedure, restorative precision, patient education, and regular follow-ups. In this article, the implant failures were categorized under surgical, restorative, and esthetic phases.

Surgical phase

Operator Training and Experience

The clinician must understand the meaning and the relative significance of terms, such as operator training, experience, and finesse. The quality of these variables may invariably affect implant success. ^, These factors are summarized in Table 1 ( Fig. 1 ).

Table 1

Implant failures in the surgical phase due to operator-related errors

Etiology	Description	Management
Overheating of bone during osteotomy	• Bone damage occurs above 47°C for 1 min. • Impaired bone healing and remodeling cause peri-implant bone loss, and implant failure.	• Copious irrigation • Experienced clinicians have minimal surgical failures.
Malpositioning of Implants	• Can lead to peri-implantitis, esthetic issues, or implant failure. • Can occur in apical, occlusal, mesial, distal, buccal, or lingual directions. • Types & Consequences : Mesiodistal : Too close to adjacent teeth → papilla height loss, poor esthetics, common in partial edentulism. Corono-apical : Shallow placement → exposed metal shoulder, esthetic issues. Deep placement → mucosal recession, inflammation, hygiene issues, common in immediate implants. Buccal/Lingual : Lingual (Palatal): Leads to ridge-lap crown, plaque retention, peri- implantitis. Buccal (Facial): Causes mucosal recession, esthetic problems.	• Proper planning and guided implant placement using surgical templates. • Respect the biologic width and avoid excessive lingual/palatal angulation. • Intra-operative checks and adjustments. • Prosthetically driven plan: Collaboration with restorative dentists. • Stay updated on best practices and technological advancements.
Stripping of the implant Site	• Occurs in dense bone when the implant is forced deeper than the osteotomy size. • Caused by excessive insertion torque, undersized osteotomy preparation, improper drill sequencing, and inadequate assessment of bone density. • Characterized by a sudden drop from high to low insertion torque during placement. • Indicates loss of bone engagement and requires immediate implant removal.	• Proper drill sequencing. • Ensure adequate primary stability.
Displacement of implants into vital structures	• Implant displacement into the maxillary sinus or nasal cavity (see Fig. 1 ) can cause oroantral fistula, maxillary sinusitis, and rarely lead to severe complications like pansinusitis, orbital cellulitis, or intracranial infections. • Implants may migrate into the nasal cavity or adjacent sinuses and even the cranial fossa. • Causes of displacement: ○ Inadequate pre-operative imaging. ○ Excessive osteotomy drilling or sinus membrane perforation. ○ Inadequate primary stability. ○ Failure of osseointegration within the first 6 mo. ○ Peri-implantitis. Negative sinus pressure affecting implant retention.	• Detailed clinical and radiographic assessments, including 3D imaging, to evaluate bone morphology, quality, and sinus proximity.
Mandibular bone fracture	• Severely atrophic mandibles (bone height <10 mm) are predisposed to fracture. • Increased risk with multiple (4 or more) or wide implants due to stress concentrations. • Incomplete osseointegration may lead to spontaneous fracture from routine functional forces.	• Preoperative CBCT assessment to ensure adequate bone dimensions (minimum 10 mm height, 5 mm width). • Bone density evaluations, especially in patients with osteoporosis or osteomalacia.
Excessive torque during insertion and compression necrosis	• Deep implant placement can cause bone compression, leading to ischemia, necrosis, and sequestration of bone. • High insertion torque in dense bone without tapping exceeds physiologic tolerance, resulting in ischemia and early necrosis, particularly in dense cortical bone with limited blood supply. Presents within a month post- placement. ^,	• Follow the manufacturer’s recommendation on ideal torque application.

A panoramic dental radiograph presents multiple upper and lower jaw implants. — Fig. 1

Flapless Implant Placement

The flapless technique of implant placement involves perforating the gingival tissue using either a tissue punch or a rotary instrument, followed by implant placement. This approach does not require flap elevation or reflection. This technique offers several advantages and, when applied with proper patient selection and precise execution, it achieves a satisfactory success rate.

However, this technique is not widely recommended except for experienced surgeons. ^, Being a blind surgical approach without flap elevation, it carries a higher risk of cortical bone perforation, improper implant depth (too deep or too shallow), bone overheating, and a reduction in keratinized-gingiva post-placement. These factors collectively increase the risk of implant failure.

Pre-operative Acute and Chronic Infections at the Implant Site

It is crucial to address any acute infections around the implant site before placement, delaying implant placement by 3 to 4 mo, where necessary. Chronic dentoalveolar infections, such as chronic periodontal disease, periodontal-endodontic lesions, and chronic periapical lesions, can impact implant success by increasing the risk of bacterial contamination at the implant site. When implants are placed in sites with unresolved chronic infections, it may lead to delayed implant periapical lesions or retrograde peri-implantitis, ultimately compromising osseointegration and leading to implant failure.

Implants may be placed successfully, even in previously infected areas, after thorough debridement and disinfection of the infected site. Immediate implant placement may be considered if primary stability is achieved and all infected tissues are meticulously removed. Otherwise, grafting the socket and delaying implant placement by approximately 3 to 4 mo allows for proper healing and reduces the risk of complications. Pre-operative and post-operative regimen, including antibiotic prophylaxis, thorough cleaning, and debridement, is required to minimize infection-related implant failure and ensure long-term success. ^,

Lack of Initial Stability

Low torque during implant placement can lead to inadequate primary stability, potentially compromising the osseointegration process. Contributing factors include over-preparation of the implant site, repeated in-and-out drilling motions, and placement in low-density bone, among others. Maintaining a conservative approach during osteotomy preparation is crucial to ensure sufficient initial implant stability. In cases where initial stability is lacking, the loose implant should be removed. If adequate bone volume is present, it may be possible to immediately replace the failed implant with a longer and wider one to enhance stability. Alternatively, if the site is deemed unsuitable, it should be abandoned in favor of a more favorable location. Another viable approach involves grafting the site and allowing a healing period of approximately 4 mo before attempting implant placement again in the same area. ^,

Implant Fracture

Implant fracture can occur either during placement or after the delivery of the implant-supported prosthesis. Implant fractures are influenced by several interrelated factors. Reduced implant diameter appears to elevate fracture risk ( Fig. 2 A) without affecting the time to failure, especially when these implants are placed in dense bone and subjected to high-insertion torque. Fractures are more commonly observed in the molar and premolar regions ( Fig. 2 B), likely due to higher masticatory forces. Design and material also play a role, with conical implants and screw-retained prostheses, showing a greater tendency to fracture. Cantilevered prostheses further increase this risk. Biomechanical overload, especially from bruxism or excessive occlusal forces, is a significant cause of implant failure. Severe peri-implant bone loss has also been linked to a heightened risk of fracture. Additionally, implant fractures tend to be more prevalent in male patients, possibly due to stronger bite forces.

Restorative phase

Failure in Single and Fixed Partial Implant Prosthesis

Failure of prosthesis occurs when its intended function is affected irrevocably, often arising due to implant, abutment failure, screw loosening, crown, abutment screw fracture, and decementation. Amongst the various prosthetic failures, screw loosening has been reported to be of the largest concern.

Loosening of Screws

The screw connects the implant to the abutment and the abutment to the prosthetic crown or fixed partial denture. The various factors causing screw loosening are detailed in Table 2 . Screw loosening is more common in anterior restorations with external connection implants, while internal connection implants show higher loosening rates in posterior restorations. The abutment’s material further impacts the outcome, with metal abutments showing a higher risk of loosening than zirconia abutments. Screw loosening can be reduced by angulation-correcting implants, torque precision, coated screws with gold or diamond, and using wider implant diameter with an increase in abutment collar length. Torque precision is required more for external hex implants than internal hex implants. Anti-resistance features and conical abutment screw head and conical implant-abutment connection have better stability and less screw loosening.

Table 2

Implant failures in the restorative phase

Type of Failure	Causes	Management
Screw loosening	• Inadequate torque. • Excessive overload and pitting corrosion in titanium. • Improper screw/abutment design. • Bruxism or parafunctional movements. • Fatigue of screws due to wear and tear.	• Use of calibrated torque wrench for precise torque application. • Implant designs with internal implant abutment connections. • Avoid excessive occlusal load and repeated tightening of screws. • Use wider implant diameters and longer abutment collars. • Use high-quality materials, like gold or diamond-coated screws.
Fracture of the framework	• High occlusal loads from teeth grinding. • Poorly designed framework. • Material fatigue from repeated loading. • Corrosion due to environmental factors.	• Use fatigue-resistant materials, such as titanium alloys or zirconia. • Ensure precise fitting of the implant framework. • Design framework with uniform load distribution. • Minimise angulation and occlusal stress by using an appropriate occlusal design.
Fracture of abutment/screw	• Over-tightening. • Multiple manipulations of screws leading to material fatigue. • Incorrect torque application.	• Use correct torque settings. • Select high-quality materials for screws and abutments. • Ensure proper alignment during placement.
Chipping or fracture of veneering material	• High occlusal forces. • Material incompatibility. • Lack of proper bonding. • Air bubble entrapment. • Material fatigue.	• Use porcelain fused to metal for better durability, as zirconia reported higher veneer chipping. • Ensure proper bonding between veneer and core material. • Avoid high occlusal forces and stress points. • Monolithic zirconia.
Decementation	• Improper manipulation of luting agent. • Voids in the luting agent. • Incompatible luting agent. • Inadequate surface preparation. • Improper fit of the prosthesis.	• Follow manufacturer’s guidelines for resin luting agent application. • Ensure complete curing of the luting agent. • Properly prepare the abutment and restoration surfaces. • Check for occlusal contacts and use occlusal guards if necessary.

Fracture of the Framework

The framework of implant prosthesis connects the implants and holds the prosthetic components in place. A fracture in the framework causes functional and esthetic failure, requiring a complete prosthesis replacement. The most common causes of framework failure are detailed in Table 2 . Not much literature is available on the effects of grinding on the framework or implant failure. The choice of material, for example, zirconia abutments, showed more microleakage than the titanium abutments. A study reported that comparing external and internal hexagon implants, the external hexagon implants failed to prevent microleakage in static and dynamic loading, compared to internal conical implants. Corrosion or material degradation due to oral environmental factors and repeated exposure to hot and cold foods, such as thermal recycling, can weaken the framework, especially in metal alloys. To avoid framework fracture, high-quality, strong, fatigue-resistant materials such as titanium alloys, zirconia, or high-noble-content metal alloys must be used. A minimum angulation in implant placement has been reported to be more successful. A new advanced system for evaluating issues with framework designing is artificial intelligence finite element analysis.

Fracture of Abutment/Screw

The abutment in a fixed partial implant-supported prosthesis is a component that connects the dental implant to the prosthetic restoration, such as crowns or fixed partial prostheses. The abutment transfers forces from the prosthetic crowns to the implant during function. Implant abutment fractures are rare. The reported abutment fractures are commonly within the internal conical implant to abutment connection. ( Fig. 3 ) Abutment screw fractures can result from over-tightening and multiple manipulations of the screw, causing material fatigue. The fracture of the abutment screw can take place at any level within the implant ( Fig. 4 ). The fractured screw needs to be removed for prosthodontic restoration. In case of single implant prosthesis, the factors affecting the fracture of abutment screw are similar, however; the rate of failures in implant-supported fixed partial restorations was greater.

Two intraoral periapical radiographs display fractured dental implants. — Fig. 3

Two medical photos present fractured implant screws and a fixed prosthesis.

Tags: Dental Clinics of North America Volume 70 Issue 1

Jul 12, 2026 | Posted by drzezo in Oral and Maxillofacial Surgery | Comments Off

Pocket Dentistry

Fastest clinical dentistry insight engine

Dental Implant Failures

Key points

Introduction