Dental implants have revolutionized tooth replacement over the past few decades, providing a durable and aesthetic solution for missing teeth. However, like any medical procedure, dental implants do have some limitations and disadvantages that should be considered. This article will provide an overview of the key limitations associated with dental implants that patients should keep in mind when weighing their restorative options.
Limitations with the surgical placement of dental implants
Anatomical limitations
Not everyone is an ideal candidate for dental implants due to anatomical limitations. Some key factors that can limit implant placement include:
- Insufficient bone volume – dental implants require adequate bone volume and density to support the implant. Areas with severe bone loss may not have enough bone to stabilize an implant.
- Maxillary sinus proximity – the maxillary sinuses in the upper jaw can limit the amount of available bone for posterior implants.
- Nerve proximity – vital structures like the inferior alveolar nerve in the lower jaw must be avoided.
- Excessive interarch space – severely misaligned jaws can result in excessive distance between arches that precludes implant placement.
Advanced procedures like sinus augmentation and nerve repositioning surgeries may sometimes help overcome anatomical limitations. However, in some cases, there simply may not be enough bone available to place dental implants.
Medical health conditions
Certain medical conditions are contraindications for dental implant surgery and can severely limit the possibility of implant placement. Some key examples include:
- Uncontrolled diabetes – poorly controlled blood sugar levels impede healing after surgery.
- Bisphosphonate therapy – medications like Fosamax weaken bone integrity and increase risk of osteonecrosis.
- Active periodontal disease – untreated gum infections will lead to implant failure.
- Radiation to the jaw – previous radiation treatment damages bone cells needed for osseointegration.
- Compromised immune system – conditions like HIV or leukemia inhibit healing abilities.
Thorough pre-operative assessment and optimization of medical conditions is necessary to evaluate candidacy. Patients with absolute contraindications may not be able to get implants at all.
Heavy smoking
Tobacco smoking is perhaps the most significant risk factor compromising dental implant success. The toxins in cigarette smoke restrict blood flow, inhibit wound healing, and increase susceptibility to infections. Heavy smokers (more than 10 cigarettes per day) have substantially higher rates of dental implant failure. Most surgeons will require patients to commit to smoking cessation before considering implants.
Financial limitations
One of the biggest limitations for patients who may want dental implants is the cost. A single implant may range from $1500 – $4000 depending on the location and specific procedures required. A full arch of implants and implant-supported prosthesis can surpass $30,000. Many patients have insufficient insurance coverage or cannot afford extensive out-of-pocket costs, precluding implant treatment. Flexible payment plans and dental tourism help improve affordability for some patients.
Limitations related to implant survival and success rates
While dental implants have proven to be a very predictable restorative option, they are still susceptible to failure in some cases. Some key factors influence long-term prognosis:
Peri-implantitis
Peri-implantitis is an inflammatory condition affecting tissues around an implant, leading to progressive bone loss. It is similar to periodontal disease in natural teeth but can rapidly lead to implant failure if left untreated. Strict oral hygiene and professional maintenance therapy are essential to prevent peri-implant disease. However, some patients remain prone to periodontal problems despite best efforts.
Mechanical overload
Excessive biting forces placed on a dental implant over an extended period can lead to mechanical overload. This can manifest as fractures of the implant, abutment screw, or prosthesis. Patients who have parafunctional habits like teeth grinding or clenching impose higher mechanical stress on implants and are at greater risk of overload complications.
Post-operative infections
Serious infections complicating the initial healing phase after implant placement may lead to failure. Risk is increased in immunocompromised patients or those with other healing impairments. Antibiotics, sterile technique, and proper wound care help safeguard against infectious problems. However, implant failure rates from infection range from 2-4% on average.
Failure to osseointegrate
On rare occasions, a dental implant may fail to osseointegrate and does not effectively integrate with the jawbone. Early loading, micromovement, contamination, or low bone density all raise the risk of a non-osseointegrated implant. Immediate implant placement into infected tooth sockets also predisposes to integration failure in some cases.
| Study | Implant system | Time period | Cumulative implant survival rate |
|---|---|---|---|
| Chrcanovic et al. 2015 | Multiple brands | 1-20 years | 95.4% |
| Moraschini et al. 2015 | Neodent | 15+ years | 89.4% |
| Jung et al. 2012 | Straumann | 12-15 years | 95.9% |
These prospective clinical studies on modern dental implant systems found survival rates exceeding 89% over more than 15 years follow-up. Still, this indicates approximately 10% failure prevalence after 1-2 decades function. No treatment modality is 100% effective for all patients. Realistic expectations are prudent.
Limitations with specific implant prosthetic restorations
The implant abutment and crown must be carefully designed and fabricated to help ensure prosthetic success and survival. Some disadvantages relate to the following prosthesis types:
Screw-retained implant crowns
Cement-retained implant crowns have higher likelihood of porcelain fractures and abutment screw loosening over time. Screw access holes also compromise strength and may increase risk of crown fracture. Careful occlusal adjustments and screw tightening help, but screw-retained implant crowns still have higher technical complication rates.
Implant-supported bridges
Fixed bridges replacing multiple missing teeth using a series of implants can develop technical problems over the long term. These include:
- Abutment screw loosening
- Cracking or fracturing of bridge framework
- Porcelain chipping or breakage
- Fracture of solder joints
Full arch implant bridges are especially prone to mechanical complications because of expansive prosthesis size and greater masticatory forces.
Overdentures
Implant overdentures have excellent clinical results. However, some notable disadvantages include:
- Ongoing adjustment and maintenance needs
- Prosthesis movement and instability
- Acrylic denture tooth wear over time
- Risk of denture base fracture
- Hygiene access more difficult than fixed restorations
Overdenture maintenance requirements are higher than conventional dentures. Implant overdentures also have more prosthetic complications than fixed implant restorations.
Zirconia implant abutments and crowns
Zirconia has favorable aesthetics and biocompatibility as an implant abutment material. However, zirconia’s hardness makes it prone to fracture and chipping long-term. Hybrid abutments integrating zirconia and titanium decrease fracture incidence. All-zirconia abutments and crowns have the highest risk of material failure.
Esthetic limitations of dental implants
Replacing natural teeth with dental implants can produce excellent functional and aesthetic results. However, achieving ideal esthetics is often more challenging with implants compared to natural teeth. Some key limitations include:
Difficult to match natural root appearance
Dental implants appear too white and opaque compared to natural tooth roots. The dark shadow of the periodontal ligament is also missing, making peri-implant tissues look shorter. This can make implant crowns seem over-bulked or artificial. Custom abutments and shaded zirconia help mask these deficiencies somewhat.
Limited ability to customize crown emergence profile
The preset angulation and shape of stock implant abutments restricts the ability to fully replicate natural crown contours and gingival architecture. This can lead to less than ideal esthetic crown contours and artificial-looking implant restorations.
Challenges matching natural translucency and fluorescence
The layered structure of natural teeth produces a vital, complex appearance impossible to reproduce in dental ceramics. Implant-supported crowns look more monochromatic and mask-like, lacking natural translucency and fluorescence. Perceptive patients may find implant crowns less pleasing than natural teeth for this reason.
Difficult to develop natural papilla fill
The interproximal papilla between implant restorations often appears deflated or missing compared to natural dentition. Improper implant position, thin tissue biotype, and lack of vascularity limit papilla regeneration around implants. Satisfactory papilla fill is challenging even with optimal surgical and prosthetic protocols.
Gingival recession over time
Gradual gingival recession is common around dental implants due to progressive bone resorption. Collar exposure and increased tooth length are unaesthetic sequelae. Pink porcelain or composite grafting provide remedies, but avoiding recession is often impossible. This can detract from long-term esthetic outcomes compared to natural teeth.
Occlusal limitations of implant prostheses
While ideal occlusion can be achieved with implant restorations in most cases, some inherent downsides impact occlusal function:
No periodontal ligament for shock absorption
Natural teeth have a flexible periodontal ligament allowing physiologic mobility and dampening forces under loading. Dental implants fuse rigidly to bone without this shock-absorbing mechanism. The lack of proprioceptive feedback also impairs reflexes protecting implants from overload.
Risk of porcelain fracture from occlusal forces
Porcelain-fused-to-metal crowns were traditionally used for implant prostheses. However, PFM crowns have comparatively high rates of veneer fracture and exposure of underlying metal. Newer monolithic zirconia crowns reduce this issue but are still vulnerable to fracture.
Difficulty matching natural occlusal curves
Ideal occlusion requires cuspal inclines and horizontal-vertical overlap matching the original natural dentition. Implant placement dictates prosthetic design, often forcing compromise of preferred occlusal contours and relationships. This can result in localized premature contacts and imbalance.
Phonetics and pronunciations changes
Missing natural tooth structure and altered occlusal contours with dental implants can affect phonetic patterns and speech. Difficulty pronouncing certain words is common after implant placement as patients adjust to new occlusal contacts. With training and time, most patients adapt, but subtle speech changes may persist.
Loose implant overdenture retention
Implant overdentures rely on various attachment systems to stabilize and retain the prosthesis. However, these retention mechanisms loosen over time, resulting in compromised stability and chewing function. Frequent adjustment is required to maintain optimal implant overdenture performance.
Maintenance and complication considerations
Consistent long-term professional maintenance and oral hygiene are mandatory with dental implants. However, despite best efforts, complications still arise:
Higher professional maintenance needs
Most patients require at least semi-annual professional implant cleaning and examination to help prevent technical and biological complications. More frequent maintenance is typical if previous problems occur. This represents increased time demands and financial costs compared to traditional dental treatment.
Risk of peri-implant mucositis
Peri-implant mucositis describes inflammation of soft tissues around an implant without bone loss. Poor oral hygiene readily causes this condition, requiring professional debridement and antimicrobial therapy to resolve. Left untreated, peri-implantitis and implant failure may follow.
Implant crown or prosthesis replacement
Implant restorations do not last indefinitely. Replacement needs due to porcelain fracture, abutment screw loosening, or other mechanical issues average 6-10% over 5-10 years. While less than natural teeth, occasional remake of implant crowns or fixed dentures should be expected.
| Complication | Reported frequency |
|---|---|
| Abutment screw loosening | 12.7% over 5 years |
| Porcelain fracture | 4.5% over 10 years |
| Peri-implant mucositis | 63.4% over 5 years |
These prospective studies confirm common technical and biological complications that practitioners and patients must be prepared to address over the implant lifespan.
Risk of implant fracture
While rare with precise treatment planning, dental implants can fracture, often from progressive fatigue and cyclic loading. Fractured implants require removal and often grafting before attempting a replacement implant. Prevention through proper case selection and occlusion is imperative.
Comparison to alternative tooth replacements
Considering the limitations discussed, how do dental implants compare to other tooth replacement options?
Versus removable partial and complete dentures
Conventional removable prostheses have drastically lower survival rates, more rapid bone resorption, impaired chewing function, and reduced patient satisfaction versus implant-supported restorations. However, dentures incur lower upfront costs for qualifying patients. Implants are superior from a clinical standpoint but remain prohibitive for many patients financially.
Versus tooth-supported fixed bridges
While bridges avoid surgery, they rely on adjacent teeth for support and often require substantial removal of tooth structure. This leads to elevated risk of decay in abutment teeth. Bridges also have lower survival rates than implant-supported crowns. However, bridges do minimize costs and treatment duration for appropriate cases.
Versus no tooth replacement
Leaving tooth gaps unrestored risks supraeruption, drifting, and tilting of opposing and adjacent teeth. This invariably worsens long-term function and esthetics. The benefits of implants, bridges, dentures, or other replacements outweigh the risks and limitations of leaving edentulous spaces unrestored in most situations.
Conclusion
Dental implants offer tremendous benefits for tooth replacement that continue to make them a preferred option for most patients. However, implants do come with a range of limitations and potential complications that the dentist and patient must carefully consider together. Realistic expectations are important, and diligent long-term care is imperative. While success and survival rates for modern osseointegrated implants are favorable, failures still occur in a portion of patients for various reasons. Weighing all restorative alternatives suited to the individual patient’s needs and limitations remains the optimal approach for maximizing satisfactory outcomes. With appropriate patient selection and execution, dental implants provide reliable tooth replacement with high levels of satisfaction and improved quality of life.
