Dental implants are tooth root like structure that is placed beneath the gums in the jawbone. It is the only replacement option for missing teeth that are naturally looking, preserve the original bone and help in new bone formation. Unlike other replacement options, they keep jawbone healthy and maintain the overall oral health.
Complications are events that occur during or after the surgery. It can be further classified as-
Surgical complications
- Hemorrhage and hematoma
- Neurosensory disturbances
- Damage to adjacent teeth
Biologic complications
- Inflammation
- Dehiscence and recession
- Periimplantitis and bone loss
- Implant loss or failure
Technical complications
- Screw loosening and fracture
- Implant fracture
- Fracture of restorative materials
Esthetic and Phonetic complications
- Esthetic complication
- Phonetic complication
The most serious complications during implant surgery is Nerve injury
Inferior alveolar nerve injury-IAN injury is most commonly encountered. The IAN terminates and give rise to mental branch and incisive branch to supply the lower anterior teeth and are located in the interforaminal area. This interforaminal region is involved in many surgical procedures like bone harvesting, orthognathic surgery, dental implant surgery, etc. The nerves involved are inferior alveolar nerve, lingual nerve, mental nerve and incisive nerve.
Causes
Direct – compression, stretch, cut, overheating, accidental puncture, etc.
Indirect – postoperative edema or hematoma especially inside the mandibular canal.
The nerve injury can cause-
- Paraesthesia – numb sensation
- Hypoesthesia – reduce sensation
- Hyperesthesia – increase sensitivity
- Anesthesia – complete loss of sensation
Neurosensory disturbances, pain, etc can occur after implant placement in the interforaminal region due to the perforation of the incisive canal and nerve or due to IAN injury during implant placement in the posterior mandible.
Bleeding is the most common complication in implant surgery
The most common reason for bleeding during implant procedure is from the sublingual artery or branches which is observed during bone osteotomy due to lingual cortex perforation. According to some studies, the canine region is at greatest risk for perforation as the sublingual artery follows a horizontal course to the direction of drill at this region. Moreover, as the lingual periosteum contains rich arterial plexus, any flap tear, mishandling increases the chances of bleeding or improper instrumentation in the deep muscle layers of the floor of the mouth could also lead to life threatening hemorrhage.
FIG: SUBLINGUAL ARTERY
Several arterial anastomosis are noted in the lower anterior lingual region of the mandible. Anastomosis between the sublingual and submental arteries in the mylohyoid muscle has also been reported in literature. However, their anatomical variations were highly debated. In a study by Bavitz et al., in 53% of cases sublingual artery was either small, unimportant or absent. In another study by Hofschneider et al., 29% of cases had missing sublingual artery and 41% had large submental branch in sublingual region. Despite the differences, these arteries may lie superficially in atrophic cases and can be a reason for hemorrhage during implant surgery.
FIG: Sub mental artery perforating the mylohyoid muscle
Accessory mandibular foramen
Few studies show presence of multiple foramina in both buccal and lingual surfaces of the mandible that vary in size, position, distribution, etc of which the median lingual foramen is more commonly reported and located 10 to 13.7 mm away from the inferior alveolar border and the lateral lingual foramen 6 mm away from the inferior alveolar border. The arteries associated with the accessory lingual foramina are sufficient enough to cause severe hemorrhage during implant surgery in inter-foraminal region of the mandible.
Preventive measures
Proper imaging
Due anatomical variations in lower anterior region, proper imaging are necessary before implant surgery to prevent any possible injury or trauma. Most commonly use diagnostic imaging are:
- Periapical radiograph.
- Occlusal radiograph.
- Orthopantamograph.
- Cone beam computed tomography scan.
Implant length
Implant length and angulations to be consider before implant surgery in inter-foraminal region. A distance of 2 mm from the roof of the canal and a distance of 10-13.5 mm from lower border of mandible (due to the presence of accessory lingual foramina) to be maintain as a safety margin. According to some studies, most of the hemorrhagic incidents were reported in the canine region with osteotomy preparation of ≥15 mm depth. Besides, digital palpation also help in anticipating the occurrence of bony perforation during osteotomy preparation.
Management
Airway management
- Observation — observe any signs and symptoms of airway obstruction.
- Nasotracheal intubation — intubation either by blind or fibre optic assisted within a limited time period.
- Cricothyroidotomy — surgical cricothyroidotomy is contraindicated and needle cricothyroidotomy is indicated in children below 12 years of age.
- Tracheostomy — most effective procedure in preventing asphyxia and also indicated when cricothyroidotomy is not possible.
- Sometimes pulling the tongue out can reduce bleeding as it may compress lingual artery against the hyoid bone.
Control of bleeding
Studies shows bimanual compressions with gauze over the wound can achieve hemostasis to some extent.
Mechanical method
Sutures, ligating clips, gauzes, sponges, etc. are successful in achieving hemostasis but can only be use if the bleeders are identified. A study by Pigadas et al. states the need for drainage of hematoma is necessary in achieving hemostasis. If surgical interventions are required for hemostasis, extraoral approach is more preferred due to better visualization, retraction and ease in ligation of arteries compared to intra oral approach. The submental artery is first ligated but if the bleeding does not stop, then ligate the lingual artery (in the Pirogoff’s triangle).
Thermal method
Electrocautery, laser coagulation, etc are also effective in controlling bleeding. If the source of bleeding is from the inflamed vessels or diffuse bleeding capillaries or from parenchymal tissues, then chemical agents might prove to be more effective than the above methods.
Chemical method
Use of vitamin K, epinephrine, tranexamic acid, protamine, desmopressin, etc can control haemorrhage but higher chances of infectious as well as noninfectious risks.
Topical hemostat like collagen, cellulose, gelatin, etc are chosen for rapid arterial bleeding but for capillary bleeding topical hemostats are the treatment of choice in controlling bleeding. According to a study by Lee et al. Floseal (contain thrombin) controls acute bleeding from anterior MIC (mandibular incisive canal) during implant surgery. Moreover, ease of application of topical hemostat also makes it a preferable option.
Advances
If all the above methods fail to control bleeding then ligation of external carotid artery may be necessary. Recent advances like use of endovascular angiography for exact location and isolation of bleeding sources and super selective catheterization of bleeders can be use as an alternative measures in the management of severe iatrogenic bleeding during or after surgical procedures.
Conclusion
Implant placement in lower anterior region is often preferred due to the favorable location and easy visualization. However, due to various reported cases of disastrous hemorrhagic accidents, all applicable preventive measures are to be followed while placing implant especially in this region to avoid life threatening complications. If all adequate measures for diagnosis and treatment planning are followed lower anterior region is no doubt a preferable area for implant placement.
