Palatal Movements Research Articles

Palatal Myoclonus Associated with Orofacial Buccal Dystonia

Palatal myoclonus is a rare condition in which there are rhythmic jerky movements of the soft palate and sometimes of the other muscles innervated by the brainstem A particularly annoying symptom is a rhythmic clicking sound in the ear due to the opening and closing of the Eustachian tube. Orofacial buccal dystonia is a focal dystonia with sustained spasms of the masticatory, facial or lingual muscles. The frequent symptoms of this disease have mainly been reported to be involuntary and possibly painful jaw opening, closing, deflecting and retruding, or a combination of the above. However, the subtle and unnoticeable involuntary movement of multiple facial muscles, which might be an infrequent symptom of orofacial buccal dystonia, makes this disease hard to diagnose. Understanding the functional orofacial anatomy that is responsible for the clinical signs and symptoms is necessary for making a proper diagnosis. Here we report on a rare case of palatal myoclonus that was associated with orofacial buccal dystonia, and such a case has not been previously reported. We describe the diagnostic approach and excellent treatment results after Botulinum toxin A (Dysport) injection and proper counseling.

Postoperative cyanotic breath-holding spells in a child with Worster–Drought syndrome

We report multiple cyanotic spells in the postoperative period in a child with Worster–Drought syndrome. A male child, 3.5 years old, 12 kg, who had experienced drooling of saliva since birth, was accepted for bilateral submandibular duct translocation and sublingual gland excision. He had delayed milestones (sat at 15 months and walked at 3 years). Difficulty in swallowing resulted in frequent vomiting during feeding and recurrent upper respiratory tract infections (URI). He was fed by his parents and could mainly swallow liquids or semi-solids. He did not require a nasogastric tube or gastrostomy for feeding. There was no history of epigastric pain or discomfort following feeds that would suggest a gastroesophageal reflux disorder. He was unable to protrude his tongue despite there being no tongue-tie. He could not speak despite normal hearing (normal brainstem auditory evoked responses) and communicated with signs. There was no history of seizures. Head noncontrast computerized tomography (NCCT) showed a paucity of periventricular white matter with prominent ventricles, gliotic areas, and bilateral frontoparietal volume loss. Other systems were normal. Before surgery, the patient did not have an URI, and no adventitious sounds were heard on auscultation. In the operating room, after instituting routine monitoring, anesthesia was induced with sevoflurane in oxygen and an IV access was secured. Following the administration of fentanyl and vecuronium, nasotracheal intubation was accomplished using a 4-mm-ID uncuffed endotracheal tube and the oropharynx packed. Paracetamol suppositories (250 ? 170 mg) were inserted rectally. Anesthesia was maintained with oxygen, nitrous oxide, isoflurane, and supplemental doses of fentanyl and vecuronium. The intraoperative period was uneventful, and at the end of surgery, which lasted for 2 h, a nasogastric tube was inserted to facilitate feeding the child after the oral surgery. Neuromuscular blockade was reversed and the trachea extubated once the patient was fully awake and breathing regularly. As he was being shifted out, he sat up and started crying. He held his breath, desaturated, and became cyanosed. Saturation improved on bag-mask ventilation with 100% oxygen. Two similar episodes of desaturation occurred. After the third, a conscious effort was made to avoid any stimulation that could precipitate crying, and he was gently shifted to his mother in the post anesthesia care unit (PACU). On retrospective questioning, the parents admitted that if they force-fed the child, he would have prolonged crying with breath-holding spells; however, there was no history suggestive of cyanosis during these episodes. Worster–Drought syndrome (WDS) is a phenotypically distinct but underdiagnosed form of cerebral palsy first described in 1956 [1]. Patients share features with bilateral congenital perisylvian syndrome, a type of childhood-onset epilepsy [1]. Worster–Drought syndrome is characterized by weakness of the orofacial and bulbar muscles, leading to difficulty in feeding, swallowing, and voluntary lip, tongue, and palate movements. Attempts at feeding can cause choking and A. Chhabra D. K. Baidya Department of Anesthesiology and Intensive Care, All India Institute of Medical Sciences, Ansari Nagar, New Delhi, India

Relationship between the oral language development and restoration of velopharyngeal closure function in Chinese toddlers with repaired cleft palate

To evaluate how the oral language development enhances articulators to function well in cleft palate movement and velopharyngeal closure in the young Chinese children with repaired cleft palate. The recordings of 78 cases of Chinese toddlers with repaired cleft palate were reviewed. This group of children aged from 27 months to 33 months (average: 30 months). Transcription using Pinyin system was made. Mean utterance count (MUC) and mean special consonant correct count (MSCC) were calculated. Correlation between MUC and MSCC was statistically analyzed. The correlation coefficient of MUC and MSCC is 0.360 (P < 0.01). There is positive correlation between the oral language development and restoration of velopharyngeal closure function. Children with repaired cleft palate should be encouraged to start oral language as early as possible and as much as possible in order to get the restoration of velopharyngeal closure function.

Effects of Respiration on Soft Palate Movement in Feeding

Cyclic soft palate elevation is temporally associated with masticatory jaw movement. However, the soft palate is normally lowered during nasal breathing to maintain retropalatal airway patency. We tested the hypothesis that the frequency and amplitude of soft palate elevation associated with mastication would be reduced during inspiration. Movements of radiopaque soft palate markers were recorded by videofluorography while 11 healthy volunteers ate solid foods. Breathing was monitored with plethysmography. Masticatory sequences were divided into processing and stage II transport cycles (food transport to the oropharynx before swallowing). In food processing, palatal elevation was less frequent and its displacement was smaller during inspiration than expiration. In stage II transport, the soft palate was elevated less frequently during inspiration than expiration. These findings suggest that masticatory soft palate movement is diminished during inspiration. The control of breathing appears to have a significant effect on soft palate elevation in mastication.

Cervical vascular and upper airway asymmetry in velo-cardio-facial syndrome: Correlation of nasopharyngoscopy with MRA

Purpose Velo-cardio-facial syndrome (VCFS), the most common genetic syndrome causing cleft palate, is associated with internal carotid and vertebral artery anomalies, as well as upper airway asymmetry. Medially displaced internal carotid arteries, often immediately submucosal, present a risk of vascular injury during pharyngeal flap surgery for velopharyngeal insufficiency (VPI). We evaluate the frequency and spectrum of cervical vascular anomalies in a large cohort of VCFS patients correlating MRA with nasopharyngolaryngoscopy in detecting at risk carotid arteries. Furthermore, we assess the relationship with respect to laterality between cervical vascular patterns and the asymmetric abnormalities of these subjects’ upper airways. Methods Cervical MRAs of 86 subjects with VCFS and 50 control subjects were independently reviewed by three neuroradiologists. The course of the internal carotid and vertebral arteries was identified within the pharyngeal soft tissues. Medial deviation, level of bifurcation, dominance, anomalous origin, and vessel tortuosity were recorded. Nasopharyngoscopy examinations were available for retrospective review in 43 patients and were assessed for palatal and posterior pharyngeal wall symmetry, true vocal cord motion and size, and for the presence or absence of carotid pulsations. The endoscopic findings were compared with MRA results. Results Of the 86 subjects, 80 (93%) had one or more vascular anomalies. 42 subjects (49%) were found to have medial deviation of at least one internal carotid artery. In 24 subjects (28%) the anomalous internal carotid artery was directly submucosal; four of these were bilateral (5% of the total sample, 17% of those with a submucosal internal carotid). Other carotid anomalies included low carotid bifurcation (44 subjects or 51%), anomalous origin of the right common carotid (32 cases, or 37%), and two cases of internal carotid agenesis/hypoplasia. Vertebral artery anomalies included vessel tortuosity (34 cases, or 40%), hypoplasia (10 cases, or 12%), looping (4 cases, or 5%), and one case of a double left vertebral artery. Though patients in our study showed an asymmetric distribution of vascular anomalies, no association was found between the laterality of palatal motion, pharyngeal fullness, or laryngeal movement and structure with ipsilateral vertebral or carotid artery anomalies. Of the 33 pulsatile carotid arteries visualized at nasopharyngoscopy, only nine were found to be submucosal on MRA. In contrast, 11 submucosal carotid arteries confirmed at MRA demonstrated no visible pulsations. Positive and negative predictive values of pulsative arteries seen endoscopically for MRA confirmation of a submucosal carotid course was 27% and 79% respectively. Conclusions Carotid and vertebral artery anomalies are common in VCFS including marked medial deviation of the internal carotid artery in close proximity to the donor site for pharyngeal flap surgery. Lack of correlation between laterality of vascular anomalies and upper airway structural asymmetry in VCFS does not support the hypothesis that palatal, pharyngeal, and laryngeal anomalies are due to secondary developmental sequences caused by in utero vascular insufficiency. The presence or absence of carotid pulsations seen by nasopharyngoscopy does not correlate with the carotid arterial depth identified on MRA. Furthermore, identification of the relative medial–lateral retropharyngeal position of a submucosal carotid affords the opportunity to modify the surgical approach. These findings further support the routine use of pre-operative neck MRA in VCFS patients in surgical planning.

Review article: the gastrointestinal complications of myositis

The inflammatory myopathies are a group of acquired diseases characterized by a proximal myopathy caused by an inflammatory infiltrate of the skeletal muscle. The three major diseases are dermatomyositis, polymyositis and inclusion body myositis. To review the gastrointestinal manifestations of myositis. Over 110 articles in the English literature were reviewed. Dysphagia to solids and liquids occurs in patients with myositis. The pharyngo-oesophageal muscle tone is lost and therefore patients develop nasal speech, hoarseness, nasal regurgitation and aspiration pneumonia. There is tongue weakness, flaccid vocal cords, poor palatal motion and pooling of secretions in the distended hypopharynx. Proximal oesophageal skeletal muscle dysfunction is demonstrated by manometry with low amplitude/absent pharyngeal contractions and decreased upper oesophageal sphincter pressures. Patients exhibit markedly elevated creatine kinase and lactate dehydrogenase levels consistent with muscle injury. Myositis can be associated with inflammatory bowel disease, coeliac disease and interferon treatment of hepatitis C. Corticosteroids and other immunosuppressive drugs comprise the mainstay of treatment. Inclusion body myositis responds poorly to these agents and therefore a myotomy is usually indicated. Myositis mainly involves the skeletal muscles in the upper oesophagus with dysphagia, along with proximal muscle weakness.

Germinoma of medulla

Germinoma occurring in the medulla oblongata is extremely rare. We report a case of primary intracranial germinoma arising in the medulla oblongata of a 24-year-old postpartum female who presented with progressive weakness of upper and lower limbs, seventh nerve palsy, and decreased palatal movements. Her MR imaging showed a heterointense mass lesion in the posterior portion of upper medulla, the histology of which was reported as germinoma. Germ cell tumors should be considered in the differential diagnosis of tumors occurring in the brain stem.

Study on the relationship between the mean utterance count and restoration of velopharyngeal closure function in young Chinese children with repaired cleft palate

Background and Objectives: It is well known that language development starts earlier and finishes later than phonetic development, but there is a tight interaction between those two in young children. Oral language development enhances articulators to function well including cleft palate movement and velopharyngeal closure. The hypothesis that there is a relationship between the mean utterance count and restoration of velopharyngeal closure function.

A novel system using the Forced Oscillations Technique for the biomechanical analysis of swallowing

Physiological studies of swallowing and the diagnosis and treatment of dysphagia are crucially dependent of detailed information of respiratory and feeding events. However, this information has been obtained by indirect and/or expensive methods, as well as by methods demanding exposure to radiation. In this context, the purpose of this study was twofold: (1) describe a new low-cost system for the analysis of the respiratory events during swallowing using the Forced Oscillation Technique and (2) evaluate the performance of this device in the description of physiological events during water swallowing. The device consists of a personal computer adapted to measurement modules able to characterize the soft palate movement, the elevation of the larynx, the duration of deglutition apnoea, and the direction of airflow at the end of the swallow apnoea. These parameters were studied in eight healthy subjects under conditions of saliva swallowing and three doses of water (5,10 and 20 mL). The system allowed a real time description of the respiratory and feeding events, which were in close agreement with physiological principles. Mean results showed an increase of the apnoea time that was not statistically significant. In contrast, a highly significant increase of respiratory impedance during swallowing was observed (p < 0.0001). The described instrument does not use radiation. It shows itself particularly well suited for studies of deglutition physiology, including mechanisms involved in airway protection during swallowing. It can also be potentially useful contributing to easy clinical bedside evaluations and biofeedback procedures for the rehabilitation of paediatric and elderly patients.

Sjogren's syndrome masquerading as nasopharyngeal carcinoma

Objective The aim of the study was to describe a case of nasopharyngeal involvement by Sjogren's syndrome masquerading as nasopharyngeal carcinoma. Methods A description of clinical and radiologic features of facial pain, nasopharyngeal bulge, middle ear effusion, restriction of palatal movement, and infiltrating nasopharyngeal mass on imaging was given. Histologic evaluation, response to treatment with steroids and hydrochloroquine, and long-term follow-up, however, subsequently indicated the mass to be secondary to Sjogren's syndrome. Conclusion A previously undescribed manifestation of Sjogren's syndrome is described.

Teaching Neuro Image : Posttraumatic palatal tremor

A 56-year-old man with head injury, loss of consciousness, and normal head CT 6 weeks prior presented with persistent headache. No neurologic deficit was elicited on examination except for involuntary rhythmic movements of the soft palate, from …

Pulse Arterial Tone and Airway Obstruction in Sleep Apnea

Objective Determine if continuous pulse arterial tone (PAT) amplitude correlates with upper airway obstructions observed during simultaneous real-time magnetic resonance imaging (RT-MRI) in subjects with Obstructive Sleep Apnea (OSA). Methods A prospective series of 20 subjects diagnosed with mild to severe OSA by polysomnography, Fujita classification, Functional Outcomes of Sleep Questionnaire (FOSQ) and Epworth Sleepiness Score (ESS) underwent continuous RT-MRI during a 90-minute nap without sedation. The upper airway at the mid-saggittal plane was visualized in real time (33 fps) using a sliding window algorithm (RTHawk system). Continuous pulse arterial tone amplitude was simultaneously monitored (Watch-PAT, Itamar Inc, Israel). Results Changes in PAT amplitude were in phase with upper airway narrowing and obstruction from tongue, soft palate, and epiglottis movements. Airway obstructive events occurred coincident to 60% or greater decreases in PAT amplitude. The image sequence associated with each PAT amplitude decrease demonstrated the precise location of the obstruction. Pre-surgical site of airway obstruction and post-surgical cause of persistent obstruction was clearly identified. Conclusions RT-MRI with simultaneous and continuous PAT signal recording during natural sleep is an innovative and improved method for more precisely characterizing airway obstructions in patients with mild to severe OSA. This approach may be valuable for planning surgical treatments, potentially improving the success of these procedures.

Multicenter Interrater and Intrarater Reliability in the Endoscopic Evaluation of Velopharyngeal Insufficiency

To explore interrater and intrarater reliability (R (inter) and R (intra), respectively) of a standardized scale applied to nasoendoscopic assessment of velopharyngeal (VP) function, across multiple centers. Multicenter blinded R (inter) and R (intra) study. Eight academic tertiary care centers. Sixteen otolaryngologists from 8 centers. Raters estimated lateral pharyngeal and palatal movement on nasoendoscopic tapes from 50 different patients. Raters were asked to (1) estimate gap size during phonation and (2) note the presence of the Passavant ridge, a midline palatal notch on the nasal surface of the soft palate, and aberrant pulsations. Primary outcome measures were R (inter) and R (intra) coefficients for estimated gap size, lateral wall, and palatal movement; kappa coefficients for the Passavant ridge, a midline palatal notch on the nasal soft palate, and aberrant pulsations were also calculated. The R (inter) coefficients were 0.63 for estimated gap size, 0.41 for lateral wall movement, and 0.43 for palate movement; corresponding R (intra) coefficients were 0.86, 0.79, and 0.83, respectively. Interrater kappa values for qualitative features were 0.10 for the Passavant ridge; 0.48 for a notch on the nasal surface of the soft palate, 0.56 for aberrant pulsations, and 0.39 for estimation of gap size. In these data, there was good R (intra) and fair R (inter) when using the Golding-Kushner scale for rating VP function based on nasoendoscopy. Estimates of VP gap size demonstrate higher reliability coefficients than total lateral wall, mean palate estimates, and categorical estimate of gap size. The reliability of rating qualitative characteristics (ie, the presence of the Passavant ridge, aberrant pulsations, and notch on the nasal surface of the soft palate) is variable.

The effect of nasal speaking valve on the speech under experimental velopharyngeal incompetence condition

Velopharyngeal incompetence (VPI) is a contributing factor to speech disorders, frequently accompanying disorders, such as cleft palate, congenital paralysis of the soft palate, and cerebrovascular disease. For the treatment of these types of dysarthria, a Nasal Speaking Valve (NSV), which regulates nasal emission utilizing one-way valve, has been reported to be effective. As the unpleasantness while wearing the NSV was less than that with the conventional Palatal Lift Prosthesis, the NSV could be worn for a longer period of time. As NSV is inserted into the nostrils, this device could easily be provided for edentulous patients. This study aimed to evaluate the effect of NSV on experimentally induced VPI condition. Intelligibility of monosyllabic speech, intelligibility of conversational speech, nasalance score and acoustic analysis were used to evaluate the effect of NSV. Local infiltration anaesthesia was achieved to the area of levator veli palatini muscle and tensor veli palatine muscle of seven adult male subjects. In all subjects, remarkable suppression of the soft palate movement could be observed after the local infiltration anesthesia. Although the utterance supported by NSV under the experimentally induced VPI condition was less natural than the normal utterance, the intelligibility was markedly improved by the device. From the results of this study, the acoustic properties of NSV on the pure VPI condition, which was enabled by the newly established experimental induction, were revealed. This experimental model was also proved to provide a basis for the improvement in the treatment modalities for VPI.

ニッケルフリーチタン基形状記憶合金を利用したラットの矯正学的歯の移動に関する研究

The purpose of this study was to evaluate the performance and the usefulness of a newly developed Ni-free Ti-based shape memory alloy (SMA) wire in orthodontic tooth movement by comparing with a nickel-titanium (Ni-Ti) alloy wire. A Titanium-niobium-aluminum (Ti-24Nb3Al) SMA wire, which was considered to be biocompatible because it contained no nickel, was newly developed and mechanical property of this new alloy was improved by severe cold rolling reduction. Twenty-one male Wistar-strain rats (age; 6 weeks) were used in the animal experiment. A Ti-Nb-Al alloy wire and an orthodontic superelastic wire (Ni-Ti alloy wire) were set in the oral cavities of rats, and orthodontic palatal movement of maxillary first molars was performed with an initial load of 15 gf. The amount of tooth movement was measured and periodontal structures were histologically examined. The Ti-Nb-Al alloy wire was effective for palatal tooth movement without any adverse reaction in rats. There was no significant difference in the amount of tooth movement between the Ti-Nb-Al group and the Ni-Ti group. Histological observation of the periodontal tissues revealed no differences between the two groups. These results indicate that Ti-Nb-Al alloy wire has excellent mechanical properties suitable for orthodontic tooth movement, suggesting that Ti-Nb-Al wire may be used as a practical nickel-free shape memory and superelastic alloy wire for orthodontic treatment as a substitute for Ni-Ti alloy wire. [doi:10.2320/matertrans.48.367]

Tempospatial Linkage of soft palate and jaw movements in feeding

Tempospatial Linkage of soft palate and jaw movements in feeding

Palatopharyngeal sling: A new technique in treatment of velopharyngeal insufficiency

(a) Pharyngeal flap and sphincter pharyngoplasty are the procedures most frequently chosen by craniofacial surgeons for surgical management of velopharyngeal insufficiency. Both operations may be complicated by obstructive breathing and even sleep apnea. (b) The purpose of this study is to evaluate the efficacy of a palatopharyngeal sling in the treatment of velopharyngeal insufficiency in cases with weak palatal mobility and its effect on breathing. Seventeen cases of post-palatoplasty velopharyngeal insufficiency were subjected to treatment by palatopharyngeal sling. This sling, created by elevation of bilateral myomucosal flaps formed of palatopharyngeus and superior constrictor muscles, passed through palatal split, sutured together and to a raw area on the oral surface of the soft palate. Pre- and post-operative evaluation was carried out by perceptual speech analysis and flexible nasopharyngoscopy. Polysomnography was used to assess the effect of the operation on breathing. Complete closure was achieved in 13 cases (76.5%) while 4 cases showed incomplete closure (2 of them showed improvement when compared with the pre-operative video). The overall improvement of speech and velopharyngeal closure was 88.2%. Polysomnography showed no obstructive breathing. Palatopharyngeal sling is a useful technique for correction of velopharyngeal insufficiency in cases with little palatal motion and it carries no risk of obstructive sleep apnea.

Three-dimensional changes in the position of unopposed molars in adults

The aim of this study was to longitudinally examine, in adults, changes of position in the three dimensions of maxillary molars unopposed for more than 10 years. Twelve healthy mature adults (six males, six females; mean age 45 years 11 months) with unopposed molars were followed-up for a mean period of 10 years 7 months. Plaster casts were made at the first and last examination. The patients presented 22 unopposed maxillary molars at both recordings and 14 posterior teeth with antagonists, at least one in each subject, without significant modifications during the study period. On three-dimensional scanned plaster casts, changes in the centroid of the occlusal surface were measured in the three dimensions. The changes observed on both occasions were compared with a t-test. Vertical displacement of unopposed molars [0.8 mm, standard deviation (SD) 0.65 mm] and controls (0.4 mm, SD 0.2 mm) was noted. The unopposed teeth overerupted more than the controls (P <or= 0.06); periodontally affected molars erupted more than periodontally healthy molars (P <or= 0.01). There was significant mesial displacement of unopposed molars without mesially adjacent teeth when compared with their respective controls (P <or= 0.04). Palatal movement was observed in the unopposed teeth (0.9 mm, SD 0.6 mm) and was significantly greater than that in the controls (0.5 mm, SD 0.3 mm; P <or= 0.02). There is displacement of unopposed teeth in the three dimensions in the long term, although this is clinically insignificant in periodontally healthy adults. The observed changes are either the result of late growth remodelling or a consequence of altered dental equilibrium following antagonist tooth loss.

Numerical simulation of soft palate movement and airflow in human upper airway by fluid-structure interaction method

In this paper, the authors present airflow field characteristics of human upper airway and soft palate movement attitude during breathing. On the basis of the data taken from the spiral computerized tomography images of a healthy person and a patient with Obstructive Sleep Apnea-Hypopnea Syndrome (OSAHS), three-dimensional models of upper airway cavity and soft palate are reconstructed by the method of surface rendering. Numerical simulation is performed for airflow in the upper airway and displacement of soft palate by fluid-structure interaction analysis. The reconstructed three-dimensional models precisely preserve the original configuration of upper airways and soft palate. The results of the pressure and velocity distributions in the airflow field are quantitatively determined, and the displacement of soft palate is presented. Pressure gradients of airway are lower for the healthy person and the airflow distribution is quite uniform in the case of free breathing. However, the OSAHS patient remarkably escalates both the pressure and velocity in the upper airway, and causes higher displacement of the soft palate. The present study is useful in revealing pathogenesis and quantitative mutual relationship between configuration and function of the upper airway as well as in diagnosing diseases related to anatomical structure and function of the upper airway.

Changes in interdental papillae heights following alignment of anterior teeth

Abstract Background Orthodontic alignment of overlapped incisors can reduce the apparent heights of the interdental papillae leading to unsightly dark triangles or open gingival embrasures. Aim To determine if certain pretreatment contact point relationships between the maxillary anterior teeth were accompanied by changes in the heights of the interdental papillae after orthodontic alignment. Methods Pre- and post-treatment intra-oral 35 mm slides, lateral cephalometric radiographs and study casts of 143 patients (60 males, 83 females) between 13 and 16 years of age were used. The patients had diastamata closed, imbricated teeth aligned and palatally or labially placed teeth repositioned. A sample of 25 patients (12 males, 13 females) between 13 and 16 years of age who had well-aligned anterior teeth at the start of treatment acted as a control group. All patients were treated for approximately 18 months. The clinical crowns of the maxillary incisors and the heights of the interdental papilla between the incisors were measured on projected images of the slides. The percentage increases or reductions in the heights of the interdental papillae were compared. Results The heights of the interdental papillae increased following palatal movement of labially placed (p &lt; 0.05) or imbricated (p &lt; 0.05) incisors and the intrusion of one incisor relative to an adjacent incisor (p &lt; 0.01). The heights of the interdental papillae reduced following labial movement of an imbricated (p &lt; 0.05) or palatally placed (p &lt; 0.05) incisor or closure of a diastema (p &lt; 0.01). Before treatment the midline papillae in the diastema subgroup were of similar length to the midline papillae in the control group, but after treatment they were markedly shorter. The interdental papillae associated with crowded or imbricated incisors were shorter than the interdental papillae in the control group before and after treatment. Conclusions Dark triangles are less likely to develop following palatal movement of labially placed or imbricated teeth and the intrusion of one tooth relative to another. On the other hand, dark triangles are more likely to develop following labial movement of imbricated or palatally placed incisors and closure of a diastema. Clinicians should be alert to the possibility of dark triangles developing in the latter group, particularly in older patients.