SINgLe IMpLANT INSerTION IN CANINe TOOTh ...

Revista Română de Anatomie funcţională şi clinică, macro- şi microscopică şi de Antropologie Vol. XIV – Nr. 4 – 2015

CLINICAL ANATOMY

Single Implant Insertion in Canine Tooth Region of Mandible Dorelia Lucia Călin1, Anca Rusu3, Mihaela Mitrea2 “Gr.T. Popa” University of Medicine şi Pharmacy, Iaşi 1. Discipline of Anatomy 2. Discipline of Cariology and Restorative Odontotherapy 3. Implantology at Private Dental Office “dr. Anca Rusu”, Bucureşti Specialist in Dentoalveolar Surgery Single Implant Insertion in Canine Tooth Region of Mandible (Abstract): The region of mandibular canine tooth is the most common location in which where occur lifethreatening haemorrhages and cause airway obstruction. The aim of this study was to evaluate the results of the insertion of a single implant in the mandibular canine region and the frequency of vascular and neuro-sensory complications associated with the procedure. Material and method: in 35 patients was carried out the insertion of a single implant in the canine mandibularregionn, immediate temporary reconstruction of edentulous area and thereafter the achievement of a metal-ceramic crowns on implant. Results: the achievement of an osteotomy depth and the use of implants having a maximum 14 mm length has prevented the perforation of blood vessels and appearance of profuse bleeding, and also the emergence of neurosensory disorders. Conclusions: The insertion of the implant in the mandibular canine region proved to be a procedure with a high acceptance and satisfaction from the patients. If all the appropriate steps required for diagnosis and treatment planning are taken and an adequate surgical protocol is followed, mandibular canine region is undoubtedly a safe zone for implant placement. Key words: single implant, canine mandibular region, vascular and neuro-sensory complications

INTRODUCTION The use of dental implants to replace a single tooth has evolved into a viable alternative that replaces the fixed prosthetic bridges. Jemt (1) described the technique of using endosseous implants, if one tooth is missing in a partially edentulous jaw. The advantages for single tooth replacement implant were related not only to aesthetic requirements, but also to the fact that adjacent teeth were not involved in prosthetic rehabilitation. Mayer et al. (2) emphasized that the implant that replaces a single tooth is an independent unit, that during its function cannot rely on neighboring teeth for lateral and tangential support. Long-term studies have reported excellent implant survival rates when it is applied to replace a single tooth (3,4). Due to its accessibility and favorable location, mandibular anterior region is often pre-

ferred for inserting of implants. Mandibular anterior area was originally considered a secure area from surgical point of view. Over time, the serious complications resulting from dental implant procedures have been reported in the scientific literature. Anatomical considerations on the anterior region of the mandible Identification of anatomical structures of the anterior mandible is extremely important for the success of the surgical procedure (5). The main vital structures in this region are: mandibular incisive canal, mental foramen and anterior intraosseous loop the inferior alveolar canal. To avoid damaging these anatomical structures is absolutely necessary to know their precise location before surgery using CT and radiographic examination (6,7). The mandibu663

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lar incisive canal is described as a continuation of the inferior alveolar canal, containing the mandibular incisive nerve, terminal branch of the inferior alveolar nerve (8,9). Studies carried out on cadavers have shown that this nerve was always present (10,11). Mandibular incisive nerve provides innervation of lower anterior teeth and the first premolar, labial bone, the surrounding gingival and buccal mucosa. The area between the left and right mental foramen is often described as interforaminal region of the mandible. Obradovic et al. (12) examined the mandibles of 105 cadavers and found the presence of mandibular incisive canal located mesial from mental foramen in 92% of 70 dentate mandibles, and only in proportion of 31% in 30 edentulous jaws. Canal diameter ranged between 0.48 and 2.9 mm. Mraiwa et al.(13) examined the mandibles of 50 bodies and showed that this canal was observed macroscopically in 96% of the jaws, and the average canal diameter was 1.8 mm. The mandibular incisive canal was located at an average distance of 9.7 mm from the lower cortical border and continued to the incisive region, with a slightly downward direction at an average distance of 7.2 mm from the lower cortical border. The canal was narrowing in its path towards the midline and reached the midline only in 18% of cases, then ends apical to lateral incisor and sometimes apical to central incisor. Mar­ dinger et al. (14) studied the mandibular incisive canal in 46 hemiarcades of cadavers and observed that the incisive neurovascular bundle was present at all anatomic specimens, crossing inside the canal. De Andrade and co-authors (15) concluded that the mandibular incisive nerve is a normal structure which extends to the midline of the jaw. The incisive nerve provides the innervation of first premolar, canine and central and lateral incisors. If it is found to be present a large incisive canal, the patient may experience discomfort during the osteotomy for implant insertion or postoperative pain which may require removal of the implant (16). Vascularization of the anterior region of the mandible The placement of the implant involves removing of alveolar ridge mucosa, achievement of a new alveolus in the mandible at a specified 664

depth, and finally placement of the implant. During this procedure the arterial blood supply of the anterior mandible between the two mental foramina may be affected. Hofschneider et al. (17) explored the position and course of these blood vessels. They found that the interforaminal region of the mandible contains the majority of vascular branches that enter into the jaw, and the fact that these vessels are interconnected. These authors also found that these vessels have a trajectory near the sublingual gland and sublingual fossa. They also affirm that these branches in this region were more often branches of the sublingual artery, although were discovered submental artery branches. In the study conducted by Loukas et al. (18) was found that mucosal branches were derived mostly from sublingual arteries. Anastomotic branches were found ascending on the lingual surface of the mandible in the region of the first premolar in 81% of cases, in the lateral incisor region in 72% of cases, and passing horizontally in the sublingual sulcus in the canine zone in 62% of cases. Mucosal branches ranged in diameter between 4 and 1.1 mm, with an average of 0.9 mm. The diameter of the vessel is able to cause a sublingual hematoma (19). In the studies from the scientific literature, was found that in canine region the sublingual artery follows a horizontal trajectory to the direction of drilling, but at 90° to the direction of rotation during drilling. Therefore, in this region the sublingual artery presents a higher risk for laceration or transection (18). In the study published by Mardinger et al. (20), the average distance from the sublingual and submental arteries to the alveolar ridge was found to be 15 mm in region of incisors and canines. These authors have also studied the distance from the arteries mentioned above to the lingual cortex, which was found to be 4 mm in the menton region and 2 mm in the area of the canines. Given these observations into consideration, the canine region is identified as being the most vulnerable, because here the arteries are running closer to lingual cortex and alveolar ridge. Medial and lateral vascular lingual canals of mandible Anatomical and radiographic studies from the scientific literature have identified the mandibular lingual vascular canals. Vascular canals

Single Implant Insertion in Canine Tooth Region of Mandible

are often present in the midline of the mandible and lateral from this line. Gahleitner et al. (21) identified between 1 and 5 canals per patient. Lingual lateral canals in the canine tooth region were present in 69% (22), 71% (23), 80% (24) of cases and the frequency of the medial lingual canals varied between 33.1% and 96.5 - 100% (22,24) in the mandibular incisor region. The location of lingual canals coincided with the most common sites with significant bleeding during insertion of the implant, canine and mandibular incisors areas being at high-risk. The diameter of the canals was approximately 1.2 mm, a dimension that is sufficient to cause sublingual severe bleeding (18). Katakami et al. (24) described the presence of anastomoses between lingual canals and inferior alveolar nerve in 20.1% of cases. Their presence may cause an increased risk due to a greater difficulty in controlling bleeding. Considerations on the surgical technique In order to prevent damage of vital anatomical structures, the precise location of these structures must be identified before the start of the surgical procedure using radiographic techniques (25). The panoramic radiographs are commonly used to locate anatomical landmarks for planning surgery for insertion of endosseous implants in mandible (26). These are useful to analyze the anatomy of mandible and adjacent anatomical structures. Mental foramen may be identified very well on radiographs, the visibility of the anterior loop and incisive canal is much lower. In a study conducted by Jalili et al. (27) the mental foramen, anterior loop of inferior alveolar canal and incisive canal were observed on 94%, 66% and 70.6% of the evaluated panoramic radiographs. In a different study conducted by Jacobs et al. (28) the mental foramen, incisive canal and anterior loop have been identified in 71%, 15% and 11% of the panoramic x-rays, and the mandibular canal was observed in 99% of cases. Determination of implant length During the introduction of implants in the anterior mandible, the length and angulation of the implant must be well planned before surgical manipulation of lingual soft tissues (29). In

order to avoid any unwanted complication, a safety margin of 2 mm from the ceiling of the canal must not be exceeded (30). Although, in all the articles published in the scientific literature, the exact site responsible for the emergence of a massive bleeding, the associated length of the implant or depth of osteotomy were not mentioned, the most of the cases of bleeding have been reported in canine region when the length of the implant or when osteotomy for the neoalveolus exceeded 15 mm (31,17). Many authors in their studies concluded that bicortical stabilization in this region is not absolutely necessary in order to succeed the implantation because cortical bone is dense. Relationship between benefit and risk should be considered before selecting a length exceeding 13 mm for the implant (32). Also, due to the presence of accessory lingual foramina at 10-13.5 mm from the inferior border of mandible, it is always safe to decrease the distance from the total height of the mandible before deciding the implant length in this region (33,34). Complications Haemorrhagic complications after the placing of a dental implant are rare, but can be serious, especially in the anterior region of mandible. It requires adequate planning of surgery, with a thorough knowledge of anatomical characteristics of surgical area and the use of complementary radiographic techniques to avoid possible risk. Despite these precautions, some patients have an increased risk of bleeding due to physiological anatomical variations. Among intraoperative complications in implant surgery, hemorrhages occupy an important place. Most commonly, these hemorrhages occurred in the interforaminal mandibular region because the most vascular arterial branches penetrate into mandible through this region. Immediate complications such as hemorrhages were rarely described, but they could be important, because hematomas occur especially at level of lingual floor. In some cases these can be life threatening and may require emergency treatment in hospital (35,36). Although interforaminal region is relatively safe area to place implants, perforation of lingual cortex during insertion of dental implants can cause severe bleeding (37,38). In addition to arterial wound, if osteotomy produces the lingual periosteum ruptures and damage to the anatomical structures of the sublin665

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gual space, the bleeding may increase, the result is a hematoma of the lingual floor (39). Dental implants that could cause major bleeding complications were most often located in the mandibular canine region, followed by the incisors and first premolar. Many authors have studied the location of major blood vessels in the jaw and their relationship to the inferior alveolar nerve and the mandibular incisive nerve and cortical bone. This bleeding is explained by the presence of sublingual and submental arteries in this area. The most common cause of heavy bleeding in the anterior mandibular region is the lingual cortical bone perforation with sublingual artery damage, in case of introduction of long implants (15 mm or more). The use of short implants in the mandibular anterior region is recommended, in order to avoid the risk of significant bleeding complications (20). Sensory disorders can be caused by direct or indirect trauma (e.g., pressure induced by a hematoma into the incisive canal) or by chronic stimulation of neurovascular bundle of incisive canal or lingual lateral canals after implant placement in the interforaminal region. After direct trauma, which can occur if the implant is placed through the bone canal, the nerve endings may undergo retrograde degeneration in most of the cases (40). Indirect trauma can be caused by a hematoma affecting neurovascular package of the mandibular incisive canal (41). As this blood clot cannot be evacuated, the inflammation presses the nerve and leads to compression neuropathy. Sensory disturbances could also be related to chronic stimulation. If the implant is placed near or on top of the nerve, the nerve can be stimulated regularly each time the patient bites or chews. It is possible that such a chronic stimulation can lead to the emergence of chronic neuropathy (42). Sensory disorders such as hypoesthesia, paresthesia and anesthesia may occur. In some cases, the sense of pain is predominantly disrupted, in others tactile senses and perception of temperature are affected (41). All these changes can be transient or persistent, depending on the extent of damage of the nervous tissue involved (43). Another undesirable effect is damage to adjacent teeth by lack of parallelism between the implant and the neighboring teeth or by exces666

sive approaching. Placing of the implant should respect a minimum distance of 1.5 mm from adjacent teeth. In case of damage and depending on its grade, the affected tooth treatment may include endodontic treatment, periapical surgery, apicectomie or extraction (44). The purpose of this study was to evaluate the result of the insertion of a single implant in the mandibular canine and the frequency of vascular and neuro-sensory complications associated with the procedure. MATERIAL AND METHOD The present study involved 35 patients (21 women and 14 men) aged between 28-46 years who presented at Private Dental Office “Dr. Anca Rusu” with esthetic and phonation disorders induced by the absence of canine tooth in mandible. Criteria for inclusion of patients in this study were: non smoking, no bone loss in the affected teeth, absence parafunctions (bruxism), the absence of periodontal disease. Patients were carefully evaluated from medical, clinical, radiological point of view in order to assess the current health status and to identify any conditions that would require pre-treatment or contraindications to treatment. To all patients was exposed the treatment plan which involved the insertion of an implant, an immediate temporary reconstruction of the breach and subsequent realization of a metal-ceramic crowns on implant. Furthermore, they were informed in detail about the surgical procedure and informed consent was obtained. An example of the performed procedure in the group of patients is presented below. The patient KI, female, aged 33 years, without other significant family history, presented at Private Dental Office „Dr Anca Rusu” accusing physiognomy and speech problems due to absence of mandibular left canine. At intraoral clinical examination was observed the absence of mandibular left canine (fig.1), being completed by radiological examination (fig.2). Panoramic radiograph was used to locate anatomical landmarks such as the mental foramen, anterior loop of inferior alveolar canal and incisive canal and to determine the length of the implant (Fig.3). CT imaging was used to determine the anatomic status and tridimensional bone offer at the proposed implantation site and evaluate the

Single Implant Insertion in Canine Tooth Region of Mandible

Fig. 1. Initial clinical appearance of the patient

Fig. 2. Orthopantomography initially performed to identify possible pathologies and anatomical landmarks

Fig. 3. Orthopantomography that highlighted inferior mandibular canal and anterior loop (red) and mandibular incisive canal (yellow)

best placement of the implants taking into account the prosthetic needs and anatomical constraints (presence of mandibular incisive canal, anterior loop).

Mandibular canine region typically allows dental implant application without further intervention. It was decided to insert a single implant in the canine region with the length less 667

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Fig. 4. Crestal incision with the detachment of vestibular flap to expose the bone

Fig. 5. Realization of neoalveolus and the insertion of parallelism pin

Fig. 6. Inserting the implant

Fig. 7. Inserting the provisional abutment on implant

Fig. 8. The provisional acrylic crown with a celluloid cape and flowable composite resin over the provisional abutment

than 15 mm in order to avoid risks of bleeding complications through sublingual artery damage. The purpose of replacing a single tooth in the anterior mandible has been the restoration of functions and appropriate aesthetics without affecting hard structures and adjacent soft tissue. 668

The patient received detailed explanations on surgical procedures that will be performed, possible complications and the informed consent was obtained from her. Antibiotic prophylaxis was performed 1 hour before the procedure, then local anesthesia. After local anesthesia a crestal incision was made, supplemented by two vertical incisions with the detachment of vestibular flap in order to expose the bone (Fig.4). The osteotomy was performed to insert the implant up to a length determined by x-ray and after it was inserted the pin for guiding and parallelization, for assessing the depth, position and angle of neoalveolus (fig.5). The Bredent implant has been inserted with a length of 14mm and a diameter of 3.5 mm, the torque was 40 (fig. 6). Addition of bone was not carried out. There wasn’t observed the existence of any lingual perforations. Subsequently, the provisional abutment was inserted in the implant (Fig.7), and then was

Single Implant Insertion in Canine Tooth Region of Mandible

Fig. 9. The final radiological appearance

performed the provisional acrylic crown with a celluloid cape and flowable composite resin over the provisional abutment (screw down crown) (Fig.8). The provisional crown was removed from occlusion. The suture was made with nonresorbable threads for the attachment of the gingiva (fig.8), followed by the application of the temporary crown which was inserted on the implant. Within three months from implant loading, the patient must be present at the cabinet in order to achieve the final crown. Administration of antibiotics continued after surgery by 1 tablet every 8 hours for the first 2 days, and in the next 5 days with 1 tablet every 12 hours. Patients were instructed to consume foodstuffs of soft consistency within 6 weeks to prevent any movement of the implant. RESULTS OTP were used to evaluate the implant-bone interface, and marginal bone level in relation to the upper part of the implant. In no case were found lingual cortex perforation and bleeding complications with hematoma formation, because were used implants with a length less than 15 mm. It has not been found radiographically the mandibular incisive canal perforation. The healing period following loading of implants went without any complications. In the case of the five implants was observed a slight swelling of the soft tissues. All 35 patients were evaluated 4 days postoperatively using clinical neurosensory tests for the incisive nerve evaluation and questioned on the sensitivity of the chin, lower lip, the labial bone, the surrounding gingiva and mouth. In

three cases there was a slight transient paresthesia at the menton, but it disappeared 2 weeks after surgery. Because temporary crowns were placed at the time of surgery, gingival tissues were supported and suffered little change in anatomy and have been obtained very good aesthetic results. Three months after the level of gum was kept. The complications that could arise were biological and technical order. There were no biological complications such as fistula formation, peri-implant mucositis or soft tissue dehis­ cence. Among the technical occurred complications, in one case was produced the provisional crown fracture. At the postoperative control carried out at 6 months it was found that implants were stable and radiologically around the implants there is no bone loss. The interdental papillae were present, “black triangles” absent and the obtained aesthetic result was satisfactory for patients. Single implant placement in mandibular canine zone proved to be a procedure with a high acceptability and satisfaction from the patients. Patient satisfaction was assessed using a scale from 0-10 (0 - totally unsatisfactory results, 10 - complete satisfaction). The average value of satisfaction of the patients involved in the study was assessed at 9.057. DISCUSSION Mandibular canine region is the most frequent location in which occurs life-threatening bleeding that causes airway obstruction as reported in the scientific literature (45,46,35). Knowledge of anatomical structures and atypi669

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cal anatomical variations in shape and size is extremely important for inserting implants, helps improve patient assessment and facilitates an extremely precise surgery. Preplanning and review of anatomy prior to surgery can help to avoid the intra and postoperative complications (47). Among intraoperative complications related to surgery of inserting implants are profuse bleeding, neurosensory changes, damage to adjacent teeth of the implant and mandibular fractures. Mardinger et al.(20) found that the average distance from the blood vessels of the mandible to the alveolar crest is 15 mm in mandibular canines and incisors region. It is therefore advisable to use short implants in the region of incisors and canines, because of the proximity of arteries to the alveolar ridge. Most of the blood vessels were located above the mylohyoid muscle in the canine region (68.7%), thus increasing the risk of bleeding. According to the studies of Loukas (18) and Rosano (33) a depth of 15 mm of osteotomy is sufficient to perforate the arterial branches. The occurrence of endosseous bleeding due to perforation of the mandibular lateral vascular canals during the implant placement may compromise the healing process, leading to proliferation of endothelial cells of blood vessels around the implant surface and compromises its osseointegration. In the region of the mandibular canine, the

sublingual artery was found crossing horizontally along the length of the sublingual sulcus. It was hypothesized that the blood vessels that travel horizontally on the direction of the drill, but perpendicular to the rotation of the drill tip, present the greatest risk of rupture and transection during lingual perforation. In the present study, the achievement of a depth of osteotomy and the use of implants having a length of maximum 14 mm avoided the perforation of blood vessels, the profuse bleeding appearance, and the emergence of neurosensory disorders. CONCLUSIONS Placement of implants in the mandibular canine region requires a thorough knowledge of the anatomical structures for the success of the surgical procedure. If all the appropriate steps required for diagnosis and treatment planning are taken and an appropriate surgical protocol is followed, the region is undoubtedly a safe zone for  implant placement. The use of short implants in the anterior mandible, avoids the risk of important bleeding complications. In this study, aesthetic and functional results obtained after loading a single implant in the mandibular canine region was satisfactory both for the patient and the dentist.

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