Lingual Retraction Research Articles

Three-dimensional finite element analysis of maxillary anterior teeth retraction force system in light wire technique

This study aims to construct a three-dimensional finite element model of a maxillary anterior teeth retraction force system in light wire technique and to investigate the difference of hydrostatic pressure and initial displacement of upper anterior teeth under different torque values of tip back bend. A geometric three-dimensional model of the maxillary bone, including all the upper teeth, was achieved via CT scan. To construct the force model system, lingual brackets and wire were constructed by using the Solidworks. Brackets software, and wire were assembled to the teeth. ANASYS was used to calculate the hydrostatic pressure and the initial displacement of maxillary anterior teeth under different tip-back bend moments of 15, 30, 45, 60, and 75 Nmm when the class II elastic force was 0.556 N. Hydrostatic pressure was concentrated in the root apices and cervical margin of upper anterior teeth. Distal tipping and relative intrusive displacement were observed. The hydrostatic pressure and initial displacement of upper canine were greater than in the central and lateral incisors. This hydrostatic pressure and initial intrusive displacement increased with an increase in tip-back bend moment. Lingual retraction force system of maxillary anterior teeth in light wire technique can be applied safely and controllably. The type and quantity of teeth movement can be controlled by the alteration of tip-back bend moment.

Displacement pattern of the anterior segment using antero-posterior lingual retractor combined with a palatal plate.

ObjectiveTo evaluate and compare the effects of two appliances on the en masse retraction of the anterior teeth anchored by temporary skeletal anchorage devices (TSADs).MethodsThe sample comprised 46 nongrowing hyperdivergent adult patients who planned to undergo upper first premolar extraction using lingual retractors. They were divided into three groups, based on the lingual appliance used: the C-lingual retractor (CLR) group (group 1, n = 16) and two antero-posterior lingual retractor (APLR) groups (n = 30, groups 2 and 3). The APLR group was divided by the posterior tube angulation; posterior tube parallel to the occlusal plane (group 2, n = 15) and distally tipped tube (group 3, n = 15). A retrospective clinical investigation of the skeletal, dental, and soft tissue relationships was performed using lateral cephalometric radiographs obtained pretreatment and post en masse retraction of the anterior teeth.ResultsAll groups achieved significant incisor and canine retraction. The upper posterior teeth did not drift significantly during the retraction period. The APLR group had less angulation change in the anterior dentition, compared to the CLR group. By changing the tube angulation in the APLR, the intrusive force significantly increased in the distally tipped tube of group 3 patients and remarkably reduced the occlusal plane angle.ConclusionsCompared to the CLR, the APLR provides better anterior torque control and canine tipping while achieving bodily translation. Furthermore, changing the tube angulation will affect the amount of incisor intrusion, even in patients with similar palatal vault depth, without the need for additional TSADs.

Lingual nerve strain during lingual flap reflection & nerve protection: a cadaver study

Placement of a lingual retractor during removal of wisdom teeth polarizes clinicians’ views. Morbidity associated with lingual nerve injury is considerable. The argument of wide exposure is protective of the lingual nerve.

Three-dimensional retraction of anterior teeth with orthodontic miniplates in patients with temporomandibular disorder

Vertical dimension control is critical for adults with Class II high-angle malocclusions. If the patient has a temporomandibular disorder, this requirement is exacerbated. When extraction is planned, the treatment challenge is further increased. This article reports on a new biomechanical design (C-therapy) appropriate for anterior segment retraction with excellent control of the vertical dimension, even in a Class II high-angle patient with a temporomandibular disorder. Maximum retraction of the maxillary anterior segment can be achieved with a lingual retractor and a palatal miniplate without appliances on the maxillary posterior segments. Mandibular anterior vertical height was well controlled by a second miniplate in the mental region. This device also contributed to mandibular anchorage reinforcement. A patient with temporomandibular disorder symptoms treated with this approach is shown.

Esthetic orthodontic treatment with a double J retractor and temporary anchorage devices

This clinical article reports an esthetic treatment option for managing a Class II malocclusion in an adult. The patient, a woman aged 24 years 2 months, had crowding and a convex profile. She was treated with maxillary first premolar extractions, a double J retractor, and temporary skeletal anchorage devices in the maxillary arch. Posttreatment records after 2 years showed excellent results with good occlusion and long-term stability.

Use of the Airtraq® optical laryngoscope for nasotracheal intubation in predicted difficult airway management in oral surgery

To the Editor, Nasotracheal intubation is usually required in oral surgery to allow an unrestricted surgical approach. The standard method is generally performed using the Macintosh laryngoscope supported by Magill forceps. However, it is recommended to perform awake tracheal intubation in situations where a difficult airway is predicted, a scenario where this technique may be poorly tolerated by the patient. Although fibreoptic intubation is considered the ‘‘gold standard’’, sometimes it is difficult to perform and, therefore, alternatives are necessary. The Airtraq NT (Prodol Meditec S.A., Vizcaya, Spain) is designed specifically for nasotracheal intubation. We present the successful use of this device in an airway that was considerably distorted due to prior multiple surgeries and radiation therapy. The patient gave written informed consent for publication of this article. The patient was a 60-yr-old, 65 kg male with oropharyngeal cancer and ischemic heart disease. He had undergone four previous surgical interventions involving three reconstructions with a muscle flap for epidermoid carcinoma in different locations of the mouth (submandibular gland, left retromolar triangle, and left vestibule). He was scheduled for excision of a recurrent tumour on the floor of his mouth. Preoperative airway assessment included a Mallampati class IV, a 2-cm interincisor gap, a 5-cm thyromental distance, Upper Lip Bite Test class III with limited cervical hyperextension, and lingual retraction. The Airtraq NT was inserted after standard monitoring, pre-oxygenation with a facemask, administration of a nasal vasoconstrictor, topical anesthesia of the naris and nasopharynx, and sedation with midazolam 1 mg iv and infusion of remifentanil 0.15 lg kg min. After observing a distorted airway, the patient’s vocal cords were visualized with a Cormack-Lehane grade II glottic view. A size 6.0 flexible endotracheal tube, previously inserted through the patient’s right nostril, passed on first attempt without requiring the use of Magill forceps or additional maneuvers (Figure, Panels B and C). Correct positioning of the endotracheal tube was confirmed by capnography before proceeding to anesthetic induction. The procedure was carried out without incident, and the patient’s trachea was extubated at the end of the operation while he was awake. Oral cancer may lead to airway difficulties resulting from pathologic changes of the oral anatomy or from cancer therapies, such as surgery and radiotherapy. The original Airtraq device was developed for orotracheal intubation and has been proven effective in patients with difficult airways. The original Airtraq has an intubation channel guide, making it impossible to introduce a tube through the nose despite various attempts to adapt its use to nasotracheal intubation. The Airtraq NT was designed to overcome this difficulty, as it is devoid of the posterior channel wall, which provides the additional space needed to facilitate the passage of the tube while still maintaining the original advantages (Figure, Panel A). The anatomically-shaped blade allows a direct route to the tracheal inlet, which facilitates visualization of the glottis and passage of the tube without having to align the oral, pharyngeal, and laryngeal axes or distort the airway structures. It therefore requires less nasotracheal tube manipulation with the Magill forceps. In cases where there are M. A. Gomez-Rios, MD (&) Complejo Hospitalario Universitario A Coruna, Coruna, Spain e-mail: magoris@hotmail.com

Prospective Analysis of Frequency and Contributing Factors of Nerve Injuries Following Third-Molar Surgery

The objective of this prospective study was to determine the incidence of injury to the inferior alveolar and lingual nerves following surgical removal of impacted mandibular third molars and to evaluate the various factors contributing to the same. A total of 119 patients underwent mandibular third-molar removal during the period of 11 months. Of 119, 3 inferior alveolar nerve and 5 lingual nerve injuries were encountered. Various factors such as lingual retraction, surgical time, operator experience, radiologic findings contributing to the injury were correlated and analyzed.

Speedy surgical-orthodontic treatment with temporary anchorage devices as an alternative to orthognathic surgery

We describe a new type of corticotomy-assisted orthodontic treatment called speedy orthodontics for treating severe anterior protrusion in adults. Once medullary bone is deformed after corticotomy, recovery to its original dimension is impossible if the greenstick fractured bone is ossified as it was deformed. Speedy orthodontics describes a protocol to allow movement of dental segments over a shorter time by using a corticotomy and an orthopedic force with temporary anchorage devices. After proper diagnosis and treatment planning, the maxillary first premolars are removed, and then a corticotomy is performed to outline a block of bone around the maxillary anterior teeth under local anesthesia. An interval of 2 weeks is optimal between the labial and lingual corticotomy for sufficient healing and less patient anxiety. The maxillary anterior teeth are fixated into a single unit with the specially designed lingual retractor. A retraction force of 500 to 900 g per side is applied to the lingual retractor and the C-palatal plate placed in the midpalatal area. After anterior bone segment retraction, finishing is performed with full fixed appliances. Correct overbite and overjet, facial balance, and improvement of lip protrusion were obtained in adults with protrusion treated by speedy orthodontics. This new type of treatment mechanics can be an effective alternative to orthognathic surgery in adults with protrusion.

Frequency Estimates and Risk Factors for Postoperative Morbidity After Third Molar Removal: A Prospective Cohort Study

The aim of this study was to estimate the frequency of postoperative complications after mandibular third molar (M3) surgery and identify the risk indicators. This was a prospective cohort study of a sample of subjects having at least 1 mandibular M3 surgically extracted at a teaching hospital in Jordan. The predictor variables were categorized as patient, anatomic, and operative specific. The outcome variables were postoperative complications recorded as present or absent. Bivariate analyses were computed, then a multivariate logistic regression model was used to identify independent predictors for the common postoperative complications. The study sample was comprised of 149 patients who had 245 extractions. The mean age was 21.6 +/- 3.32 years; 64.9% were females. In the multivariate logistic regression model, age (P = .033, odds ratio [OR] = 1.178), M3 side in relation to the handedness of the operator (P = .048, OR = 4.078), and lingual retraction (P = .001, OR = 11.293) were the variables found as independent predictors for alveolar osteitis. The level of impaction had a significant association with trismus, and operation time acted as an independent predictor for pain (P < .001, OR = 1.085). Postoperative morbidity increases with older age, deeper impaction, M3 side differing from the handedness of the operator, and longer procedures.

Class II malocclusion treated by combining a lingual retractor and a palatal plate

In this article, we describe the treatment of a woman, aged 25 years 8 months, with a Class II malocclusion, severe anterior protrusion, and a high mandibular plane angle. The treatment plan consisted of extracting both maxillary first premolars and mandibular second premolars. En-masse retraction of the 6 maxillary anterior teeth was performed with a lingual approach combining a C-lingual retractor and a C-palatal plate (C-plate). However, the mandibular dentition was treated with conventional labial fixed appliances. After the maxillary anterior retraction, labial fixed appliances were placed on the maxillary dentition only during the finishing stage. Correct overbite and overjet, facial balance, and improved lip protrusion were obtained. The active treatment period was 17 months, and the results were stable for 13 months after debonding. This C-lingual retractor and C-plate combined retraction method can be effective for intrusive retraction of the anterior teeth.

There Are No Back Vowels: The Larygeal Articulator Model

AbstractAs an alternative to the high-low-front-back model of vowel specification, thelaryngeal articulator modelis proposed, based on a reinterpretation of how the vocal tract functions to produce laryngeal and pharyngeal sounds. Evidence drawn from numerous laryngoscopic studies demonstrates the scope of articulatory behaviours possible in the pharynx. For a broad sample of languages, lingual retraction is shown to accompany laryngeal/pharyngeal gestures, motivating the redistribution of vowel quality designations. The vocal tract is divided into two articulatory components: the laryngeal articulator and the oral articulator. The vowel chart is split into three sectors: front, raised, and retracted. Whereas front vowels can be qualified as close or open, so-called back vowels are re-designated as either raised or retracted, and the role of retraction as a function of the laryngeal constrictor mechanism is elaborated.

An Audit of UK Oral and Maxillofacial Surgeons on the Use of Lingual Retraction during Third Molar Removal

(Robinson P; Loescher A)

Lingual Access and Lingual Retraction for Removal of Third Molars: A Long-Term Study

Lingual Access and Lingual Retraction for Removal of Third Molars: A Long-Term Study

There Are No Back Vowels: The Laryngeal Articulator Model

As an alternative to the high-low-front-backmodel of vowel specification, the laryngeal articulator model is proposed, based on a reinterpretation of how the vocal tract functions to produce laryngeal and pharyngeal sounds. Evidence drawn from numerous laryngoscopic studies demonstrates the scope of articulatory behaviours possible in the pharynx. For a broad sample of languages, lingual retraction is shown to accompany laryngeal/pharyngeal gestures, motivating the redistribution of vowel quality designations. The vocal tract is divided into two articulatory components: the laryngeal articulator and the oral articulator. The vowel chart is split into three sectors: front, raised, and retracted. Whereas front vowels can be qualified as close or open, so-called back vowels are re-designated as either raised or retracted, and the role of retraction as a function of the laryngeal constrictor mechanism is elaborated.

Coronectomy: A technique to protect the inferior alveolar nerve

Damage to the inferior alveolar nerve when extracting lower third molars is often caused by the intimate relationship between the nerve and the roots of the teeth. The technique of coronectomy, or intentional root retention, may minimize this problem. Forty-one patients underwent coronectomy on 50 lower third molars with follow-up of at least 6 months. The technique of coronectomy deliberately protected the lingual nerve as part of the surgical procedure. All roots were left at least 3 mm below the buccal and lingual plates of bone. All patients were radiographed preoperatively, immediately postoperatively, and after 6 months. There were no cases of inferior alveolar nerve-involved damage in this study of 41 patients who underwent 50 coronectomies. There was 1 case of transient lingual nerve involvement, probably from the use of the lingual retractor. One patient required subsequent removal of the roots of both lower third molars because of failure to heal, and 1 patient required subsequent removal of a root because of subsequent migration to the surface. Root migration was noted in approximately 30% of patients over a 6 month period. Coronectomy appears to be a viable technique in those cases where removal of the whole tooth might put the inferior alveolar nerve at considerable risk of damage. The technique appears to be associated with a low incidence of complications, but subsequent migration of the roots may be an issue in the long term.

Lingual flap retraction for third molar removal

Purpose Lingual nerve damage following lower third molar surgery remains a clinical problem. The traditional approach in the United States has been a buccal approach avoiding exposure or surgery on the lingual side of the crest of the ridge. An alternative technique is to deliberately expose the lingual tissues and retract the lingual nerve lingually before tooth removal. This study reports a trial of this technique. Materials and methods Patients had removal of their lower third molars carried out using a technique that raises a lingual flap in addition to a buccal flap and places a specially designed lingual retractor to ensure that the lingual nerve is held out of the surgical field. This technique was used in cases where the crown of the tooth had to be sectioned or when distal bone needed to be removed. Results Two hundred fifty patients were treated by this method. There were 4 cases of transient lingual paresthesia, presumably caused by traction pressure from the retractor. Three of these cases were mild and resolved within 3 weeks. The fourth case had more profound paresthesia, but still resolved within 2 months. There were no cases of permanent nerve damage, and in many cases removal of the third molar was simplified by the superior access. Conclusion Lingual retraction for third molar removal improves access to the surgical site and can simplify third molar removal. In this prospective study there were no cases of permanent lingual nerve injury.

Coronectomy in lower third molar removal

Hypothesis: That coronectomy is an acceptable technique for the management of selected impacted lower third molars in close relationship to the inferior alveolar nerve. Significance: Inferior alveolar nerve involvement with lower third molar removal remains a clinical problem with considerable morbidity. Materials and Methods: Thirty patients, needing lower third molar removal and with the tooth in critical relationship to the inferior alveolar nerve, were enrolled in this study. Evaluation was with Panorex radiograph with added CT scanning in selected cases. Surgically a buccal and lingual flap was raised, a lingual retractor was placed, and the crown of the lower third molar was removed at an angle of 45° from buccal to lingual. The crown was drilled off completely rather than only going through two thirds of the way and then cracking the crown off. The lingual retractor protected the lingual nerve during this procedure. Once the crown had been removed additional buccal root was removed until the whole remaining root fragment of the tooth was at least 3 mm below the crest of the bone. The socket was then irrigated and a watertight primary closure obtained. Results: Thirty patients had a total of 41 lower third molars treated by coronectomy. No cases of inferior alveolar or lingual nerve involvement were noted. There were no cases of wound breakdown. Follow-up radiographs taken at 6 months following the removals indicate that bone has formed over the residual roots. There have been no complications and no patients have required re-exploration. Follow-up varies from 3.1 years to 7 months, and to date there has been no sign of eruption of the residual roots. Discussion: Inferior alveolar nerve damage following third molar removal remains a significant problem in oral and maxillofacial surgery. The relationship of the nerve to the roots can be diagnosed in 3 dimensions with a combination of panoral radiograph and CT scanning, and where there is an intimate relationship and the tooth still needs to be removed, coronectomy appears to offer some advantages over conventional techniques. It can only be used for vertical or mesioangular impactions and is not suitable for horizontal impactions where the nerve may be damaged by sectioning the tooth. Conclusion: Coronectomy is a successful technique for dealing with impacted lower third molars where the roots are in intimate relationship to the inferior alveolar nerve.

Increased tendency to temporary nerve damage with lingual retractor use

Question: Does use of lingual retractor increase risk of nerve damage in third molar retraction? Objective To review the incidence and recovery of lingual nerve damage after the removal of the third molar by three different techniques.Data sources Medline, Health Star, Current Contents, Allied and Alternative Medicine, Life Sciences, Web of Science, Nursing Allied Health and the Cochrane library, up to May 1999. The index of the Journal of Oral and Maxillofacial Surgery Clinics of North America 1989–1998 was also searched together with the bibliographies of identified studies.Study selection Original cases of lingual nerve damage due to third molar removal with >6 months follow-up and clinically objective sensory testing. Three different surgical methods were evaluated: buccal approach with lingual retraction (BA+), buccal approach without lingual retraction (BA−) and lingual split technique (LS).Results Although 51 studies addressed the issue of lingual nerve damage only eight met the inclusion criteria. All comparisons of temporary nerve injury rates between the three surgical groups were significant (P<0.001). A summary of the results is presented below (Table 1).Conclusion The current literature does not show or support any significant advantage for the use of a lingual flap retractor to protect the lingual nerve during third molar surgery. It does show an increased tendency for temporary injury, however.

Links between anaesthetic modality and nerve damage during lower third molar surgery

Objective To investigate the relationships between eruption status, gender, social class, grade of operator, anaesthetic modality and nerve damage during third molar surgery. Design Two centre prospective longitudinal study. Setting The department of oral and maxillofacial surgery, University Hospital Birmingham NHS Trust and oral surgery outpatient clinics at Birmingham Dental Hospital. Subjects A total of 391 patients had surgical removal of lower third molars. Sensory disturbance was recorded at one week post operatively. Patients with altered sensation were followed up at one month, three months and six months following surgery. Results 614 lower third molars in 391 patients were removed. Forty-six procedures (7.5%) were associated with altered sensation at one week with three procedures (0.49%) showing persistent symptoms at six months. Of these 46 nerve injuries, 26 (4.23%) involved the lingual nerve and 20 (3.25%) the inferior dental nerve (IDN). All three persistent sensations were IDN related. A logistic regression model found that the use of a lingual retractor χ2=11.559, p=0.003 was more significant than eruption status χ2=12.935, p=0.007. There was no significant relationship between anaesthetic modality, age, social class, sex and seniority of operator. Conclusions There was no link between the choices of local or general anaesthesia and nerve damage during lower third molar removal when difficulty of surgery was taken into account.

Relationship between type of anaesthetic and nerve damage in lower third molar surgery

Objective To investigate the relationships between eruption status, gender, social class, grade of operator, anaesthetic modality and nerve damage during third molar surgery. Design Two centre prospective longitudinal study. Setting The department of oral and maxillofacial surgery, University Hospital Birmingham NHS Trust and oral surgery outpatient clinics at Birmingham Dental Hospital. Subjects A total of 391 patients had surgical removal of lower third molars. Sensory disturbance was recorded at one week post operatively. Patients with altered sensation were followed up at one month, three months and six months following surgery. Results 614 lower third molars in 391 patients were removed. Forty-six procedures (7.5%) were associated with altered sensation at one week with three procedures (0.49%) showing persistent symptoms at six months. Of these 46 nerve injuries, 26 (4.23%) involved the lingual nerve and 20 (3.25%) the inferior dental nerve (IDN). All three persistent sensations were IDN related. A logistic regression model found that the use of a lingual retractor χ2=11.559, p=0.003 was more significant than eruption status χ2=12.935, p=0.007. There was no significant relationship between anaesthetic modality, age, social class, sex and seniority of operator. Conclusions There was no link between the choices of local or general anaesthesia and nerve damage during lower third molar removal when difficulty of surgery was taken into account.