Complications and failures in implantology
Oral implantology is a highly reliable discipline. Like all therapies, implant treatments carry risks of complications and failure.
These complications can be classified according to their time of occurrence:
- Intraoperative complication;
- Post-operative complication.
And it is important to distinguish between the different types of failure:
- Implant failure: this jeopardizes the viability of the implant. There are two types of failure:
- primary or early failure: It occurs before implant loading, during the osseointegration period;
- secondary or late failure: It occurs after loading of the implants.
- Prosthetic failures: they only jeopardize prosthetic reconstruction.
- Therapeutic failures: these are failures in the design of the surgical and prosthetic project.
2) Success criteria for implant treatment:
Implant success is defined as an implant fulfilling its function for many years, without pathological symptoms, ensuring maximum comfort for the patient.
❖ Criteria for biological success of the implant:
- lack of clinical mobility;
- absence of peri-implant radiolucent image;
- stability of the peri-implant bone level;
- absence of pain, infection, sensory or sensory disturbances;
- prosthetically usable implant.
❖ Prosthetic success criteria:
- absence of cracking or fracture of the ceramic, fracture of the framework, unscrewing or other complications of the prosthetic components;
- perfect integration of the prosthesis: phonetic, aesthetic and functional;
- prosthetic design allowing good hygiene and good maintenance by the patient.
3) Intraoperative complications:
3.1) Bleeding:
Bleeding can occur when:
- from a soft tissue incision: Improper positioning of the incisions, beyond the vestibule, causes significant bleeding.
- bone preparation of the implant site: hemorrhage occurs as a result of perforation of the lingual cortex during drilling in the anterior area of the mandible may result in section of the sublingual artery, which is a branch of the lingual artery, or the submental artery, which is a branch of the facial artery.
- Prevention:
- carry out a thorough patient history and screen for possible blood clot disorders;
- an appropriate and atraumatic surgical technique;
- know the anatomy of the region so as not to damage:
- in the mandible, the sublingual, mylohyoid and inferior alveolar arteries;
- in the maxilla, the nasopalatine and greater palatine arteries;
- limit incisions to keratinized tissue as much as possible;
- carry out a wide approach in order to visualize and protect risk areas.
3.2) Neurological lesions:
Severe nerve damage is only found in the mandible; it may involve the inferior alveolar nerve, the mental nerve, or the lingual nerve.
- the inferior alveolar nerve: to avoid this, a safety zone of 2 mm above the inferior alveolar canal must be respected. If a break-in is observed, the position of the implant must be modified;
- the lingual nerve: which can occur during a traumatic elevation of the soft tissues, at the level of the internal cortex in the mandibular region.
- Prevention:
- Careful radiological examination and use of surgical guides;
- Handle soft tissues gently, especially at the level of the internal cortex of the mandible and at the emergence of the mental nerve.
- Use safety stops when drilling.
3.3) Pain:
Pain can be due to:
- Excessive bone trauma during implant site preparation;
- Aggressive manipulation of soft tissues inducing tissue necrosis;
- Root fracture of adjacent teeth;
- Partial or total injury to a nerve.
- Prevention:
- Radiographic analysis and use of a surgical guide;
- Take an X-ray after the pilot drill has been passed;
- Choice of implant.
3.4) Bone damage (Bone heating/necrosis):
Heating of the bone due to drilling is a major factor in this necrosis. One study showed that irreversible bone damage occurs after 1 minute of exposure to a temperature of 53°C. At temperatures above 60°C, bone necrosis occurs.
- Prevention:
- The drill bit: must be sharp and have maximum cutting efficiency.
- Respecting the drilling sequences avoids unnecessary heating of the site.
- Proper drilling technique.
- Sufficient irrigation with serum.
- Drill speed: does not have a significant impact on bone heating if all the previous precautions are taken and if the equipment usage standards are respected.
4) Post-surgical complications:
4.1) Cellular and vascular complications:
4.1.1) Edema:
Dental implant procedures are frequently associated with the development of localized postoperative edema. The edema is proportional to the trauma caused by the procedure: the shorter the tissue trauma and the shorter the procedure, the less postoperative edema will be. Edema can also strain the stitches, which in some cases lacerate the flap.
Local edema can be prevented or reduced by administering anti-inflammatories systemically and/or by locally infiltrating a few cc of cortisone [Solu-Medrol®] at the mucosal level.
4.1.2) Hematomas and bruises:
They correspond to blood stasis in the tissues and appear in subjects with capillary fragility. Traumatic manipulation of soft tissues and large flaps favor their appearance.
They can occur on the face, temples and cheeks, and can extend down to the base of the neck.
Applying wet gauze compresses to the operated area can prevent this postoperative complication.
4.2) Nerve complication (Sensitivity disorders):
Partial or total damage to the inferior alveolar-dental nerve;
- Prevention:
- A safety margin of 2 mm must be respected at a distance from the dental canal;
- Treatment :
- Radiological analysis (CT scan), removal of the implant or its displacement in the coronal direction in the case of compression of the canal.
- On the other hand, in the presence of a partial lesion, sensory disorders regress spontaneously within a few months.
4.3) Infectious complication:
An infection of the site, accompanied by pain, swelling, redness and pus, may occur a few days or weeks after the procedure due to:
- external contamination (lack of asepsis);
- a prior infection of the implant site (cyst, granulomas, endodontic or periodontal lesions);
- forgetting the sutures.
They almost never occur due to a bacterial buildup of oral flora.
- prevention:
- periodontal preparation prior to the intervention;
- preoperative antiseptic mouthwashes;
- strict adherence to the surgical protocol;
- systematic antibiotic coverage.
- treatment :
- Drain the abscess, clean the wound [H2O2 – 2% chlorhexidine – Betadine] and administer systemic antibiotics.
Most of the time, this type of infection leads to a reduction in the possibilities of osseointegration of the implant, more or less significant bone resorption and therefore, ultimately, to the loss of the implant.
4.4) Sinus complications:
- In a healthy sinus, an implant penetration of 1 to 3 mm remains asymptomatic if aseptic conditions are respected.
- On the other hand, rupture of the Schneiderian membrane can cause pain, sinusitis, hemosinus, fistulas or oro-sinus communications.
- prevention:
- It requires careful analysis of the available bone volume,
- compliance with asepsis during the surgical procedure,
- an ENT examination to rule out any sinus pathology prior to the procedure.
- If sinus pathology is identified, it should be managed by an ENT specialist.
4.5) Mucosal complications:
- Exposure of the cover screw: improper closure of the surgical site or insufficient burial of the implant.
- Gingival abscess: This is often the result of loosening of the screw or healing abutment. This gap formed with the implant promotes the appearance of an abscess which can compromise the osseointegration of the implant.
- An X-ray check can prevent this complication.
5) Post-implantation complications:
5.1) Biological failure: failure of osseointegration:
Failure due to lack of osseointegration may occur during the burial period or at the time of commissioning.
Clinically translated: mobility, or significant peri-implant bone loss.
❖ Factors of failure of osseointegration:
- Heating of the bone;
- External contamination or prior infection of the implant site;
- Excessive bone compression;
- Lack of vascularization of the bone;
- Insufficient blocking of the implant;
- Premature loading of the implant.
5.2) Functional failures:
5.2.1) Phonation:
These disorders are mainly found in the maxilla for implant-supported fixed prostheses.
The pronunciation of certain letters (S and T in particular) is very difficult.
A 3-month phonetic adaptation period is often sufficient. If the problems persist after this period, a synthetic modification is necessary.
5.2.2) Position of the tongue:
Patients may experience temporary discomfort when inserting an implant-supported prosthesis after long-term uncompensated edentulism.
5.2.3) Food retention:
Brushing access may be limited by some synthetic implants. False gums and/or the close proximity of implants can make effective plaque control difficult.
5.3) Mechanical complications and failures:
5.3.1) In covering prosthesis:
❖ Fracture of the synthetic base:
- In the mandible, the implants are located in the anterior region, where the synthetic base is narrowest.
- The connection of the female elements of the attachment requires the creation of cavities at this location, further weakening the synthetic base which will present repeated cracks and fractures.
- Prevention:
- Reinforcement of the synthetic base must be systematic when connecting the female attachments in the removable prosthesis that we want to stabilize.
❖ Fracture of the antagonist prosthesis:
- Fracture of the opposing maxillary prosthesis is quite common in cases where an implant-supported bridge is placed in the mandible.
- Prevention:
- Systematic reinforcement of the antagonist prosthesis must be carried out using a cast plate included in the resin.
5.3.2) In fixed prosthesis:
❖ Fracture of the frame:
- Fracture of Brânemark implant-supported bridges.
- Fracture at the span level => major casting defect.
- Fracture at the level of the extension of the frame => extension too long.
- Prevention:
- Extensions to the mandible should not exceed a length of 15 mm.
- Avoid extension elements in cases of small-extent partial denture reconstruction.
❖ Fracture of the prosthesis screw:
- This complication is most commonly reported because the prosthesis screw is the weak link in the synthetic implant system.
❖ Fracture of the MOVI prosthesis screws:
- Fracture of abutment screws inside the implant is a major complication.
- Managing the fracture of the abutment screw inside the implant is a difficult procedure; failure to extract it results in loss of the implant.
❖ Fracture of the cosmetic material:
- This complication mainly occurs when the occlusion is poorly balanced or when the screw access hole is located close to the occlusal edge. If the fracture of the cosmetic material represents a small fragment of ceramic, its replacement with a specific composite resin can be performed.
- If, on the contrary, a significant piece of the cosmetic material has fractured, replacement of the prosthesis is essential.
❖ Unscrewing the abutment screw:
- In the case of a screw-retained prosthesis, unscrewing the abutment screw is not a problem. Indeed, after removing the composite covering the screw and unscrewing it, the prosthesis is removed and the accessible abutment screw can be easily tightened.
- In the case of a cemented supra-implant prosthesis, the maneuver is a little more complicated.
❖ Unscrewing the prosthesis screw:
- In the case of screw-retained prostheses, the prosthesis screw is covered with a composite resin for aesthetic purposes. To make the screw easier to access in case of unscrewing, it is a good idea to place a cotton ball at the screw head and then cover it with the resin.
- This will make it easier to access the screw head without risking damage to the screw.
- A retro-alveolar X-ray is then carried out to detect any connection defects, then a cotton pellet is again placed and covered with the bonded composite resin.
❖ Deterioration of the internal thread of the implant:
- It occurs when a healing screw or abutment screw is poorly engaged in the axis of the implant, and forced.
- This complication is managed if the implant system has a tap adapted to the internal thread of the implant.
❖ Loosening of sealed prostheses:
- The main cause of loosening is the low height of the false stumps (3 to 4 mm) in the posterior sectors.
5.4) Aesthetic complications:
5.4.1) Bad positioning
❖ Wrong drilling axis:
This is the most common complication encountered in single-unit prosthetics. If the implant axis is very different from the ideal axis, it will be an implant failure and the only way to manage it is to remove the implant and reimplant in a correct axis. However, the use of angled abutments can sometimes correct the implant axes. This remains a compromise solution, because the aesthetics are not fully restored with these abutments.
❖ Inadequate implant burial level:
Aesthetic success depends on the position of the prosthesis-abutment junction, which must be located between 0.5 mm (on reduced periodontium) and 3 mm (thick periodontium) below the gum. When anatomical conditions do not allow the implant to be positioned in an ideal position, it will be preferable to first perform a technique to increase the volume of the indented ridges.
❖ Poorly positioned gingival neck:
The problem of the neck position is particularly detrimental in subjects with a gummy smile and/or a thin gingival biotype. If the available gingival volume does not guarantee a satisfactory aesthetic result, it will be preferable to resort to mucosurgical techniques before any implant procedure.
5.4.2) Implant placed at the level of the embrasures:
For optimal aesthetic results, the implant emergence must be located opposite a prosthetic element. If the implant is placed at the level of an embrasure, i.e. between two prosthetic crowns, the aesthetic result will be poor.
- If the implant is located in the middle of the interdental space, the prosthetic piece can be masked with pink resin.
5.4.3) The interdental papilla:
The loss of papillae in the anterior sector results in the formation of “black holes”, a real aesthetic detriment. This is why their preservation following an extraction, or their new formation in cases of long-standing edentulism, represents a real challenge in implant therapy.
❖ Management:
In addition to mucosurgical techniques to increase tissue volume at the papillae, the practitioner can use certain tricks to mask a mucosal defect:
- The use of pink ceramic false gums helps compensate for the loss of papillae. Attached to the prosthetic crown.
- A more apical contact point allows the interdental embrasure to be closed, thus giving the illusion of having an ideally shaped interdental papilla.
5.5) Bacterial complications:
❖ Mucositis:
Mucositis is a reversible inflammation of soft tissues due to bacterial contamination without bone loss. In most cases, mucositis gradually progresses to peri-implantitis. Diagnosis is made by peri-implant probing for suppuration or bleeding.
❖ Peri-implantitis:
It is an inflammatory process that occurs around an implant. It is characterized by inflammation of the soft tissues and progressive loss of peri-implant tissue. It is often preceded by mucositis.
Its etiology is inflammatory, it is caused by poor patient hygiene or by cement that was not completely removed during prosthetic sealing.
The diagnosis of peri-implantitis is based on the following signs:
- bleeding on probing often associated with suppuration;
- deep pocket > 4 mm;
- loss of bone support of at least 3 turns (approximately 2 mm).
Conclusion :
The best way to manage failure is to avoid it, and this is achieved by applying preventive measures involving a complete pre-implant assessment, a carefully considered treatment plan, good training of the practitioner and their ability to most accurately assess their level of skills, and rigorous maintenance.
The practitioner who, faced with a complication, does not know how to manage the situation is then at fault. It therefore seems essential to know how to manage the unexpected and to have considered an alternative solution with the patient, from the initial treatment plan.
Finally, we remind you that it is important to put things into perspective, because therapeutic failure remains rare.
Complications and failures in implantology
Wisdom teeth can cause pain if they erupt crooked.
Ceramic crowns offer a natural appearance and great strength.
Bleeding gums when brushing may indicate gingivitis.
Short orthodontic treatments quickly correct minor misalignments.
Composite dental fillings are discreet and long-lasting.
Interdental brushes are essential for cleaning narrow spaces.
A vitamin-rich diet strengthens teeth and gums.