Recommended Reading

Examination for Diplomate, American Board of Craniofacial Dental Sleep Medicine

Basic Sleep Medicine

Pathophysiology

  • Dempsey JA, Veasey SC, Morgan BJ, O'Donnell CP. Pathophysiology of sleep apnea. Physiol Rev. Jan;90(1):47-112.

  • Malhotra A, White DP. Obstructive sleep apnea. Lancet. Jul 20 2002;360(9328):237-245.

Mortality

  • Marin JM, Carrizo SJ, Vicente E, Agusti AG. Long-term cardiovascular outcomes in men with obstructive sleep apnoea-hypopnoea with or without treatment with continuous positive airway pressure: an observational study. Lancet. Mar 19-25 2005;365(9464):1046-1053.

Physiology of Pharynx

  • Ayappa I, Rapoport DM. The upper airway in sleep: physiology of the pharynx. Sleep Med Rev. Feb 2003;7(1):9-33.

Insomnia

  • Beneto A, Gomez-Siurana E, Rubio-Sanchez P. Comorbidity between sleep apnea and insomnia. Sleep Med Rev. Aug 2009;13(4):287-293.

Headache

  • Graff-Radford SB, Teruel A. Cluster headache and obstructive sleep apnea: are they related disorders? Curr Pain Headache Rep. Apr 2009;13(2):160-163.

  • Graff-Radford SB, Newman A. Obstructive sleep apnea and cluster headache. Headache. Jun 2004;44(6):607-610.

Bruxism

  • Abe S, Yamaguchi T, Rompre PH, De Grandmont P, Chen YJ, Lavigne GJ. Tooth wear in young subjects: a discriminator between sleep bruxers and controls? Int J Prosthodont. Jul-Aug 2009;22(4):342-350.

  • Lavigne GJ, Khoury S, Abe S, Yamaguchi T, Raphael K. Bruxism physiology and pathology: an overview for clinicians. J Oral Rehabil. Jul 2008;35(7):476-494.

  • Landry ML, Rompre PH, Manzini C, Guitard F, de Grandmont P, Lavigne GJ. Reduction of sleep bruxism using a mandibular advancement device: an experimental controlled study. Int J Prosthodont. Nov-Dec 2006;19(6):549-556.

  • Gagnon Y, Mayer P, Morisson F, Rompre PH, Lavigne GJ. Aggravation of respiratory disturbances by the use of an occlusal splint in apneic patients: a pilot study. Int J Prosthodont. Jul-Aug 2004;17(4):447-453.

  • Ohayon MM, Li KK, Guilleminault C. Risk factors for sleep bruxism in the general population. Chest. Jan 2001;119(1):53-61.

Pain

  • Lavigne, Gilles; Cistulli, Peter; Smith, Michael. Sleep Medicine for Dentists: A Practical Overview. Quintessence Books. 2009

Analysis of Polysomnogram Reports

PSG

  • Kushida CA, Littner MR, Morgenthaler T, et al. Practice parameters for the indications for polysomnography and related procedures: an update for 2005. Sleep. Apr 1 2005;28(4):499-521.

  • Ruehland WR, Rochford PD, O'Donoghue FJ, Pierce RJ, Singh P, Thornton AT. The new AASM criteria for scoring hypopneas: impact on the apnea hypopnea index. Sleep. Feb 1 2009;32(2):150-157.

  • Sleep-related breathing disorders in adults: recommendations for syndrome definition and measurement techniques in clinical research. The Report of an American Academy of Sleep Medicine Task Force. Sleep. Aug 1 1999;22(5):667-689.

Imaging

  • Ahmed MM, Schwab RJ. Upper airway imaging in obstructive sleep apnea. Curr Opin Pulm Med. Nov 2006;12(6):397-401.

Imaging and OAT - Cephalometry

  • Liu Y, Lowe AA, Fleetham JA, Park YC. Cephalometric and physiologic predictors of the efficacy of an adjustable oral appliance for treating obstructive sleep apnea. Am J Orthod Dentofacial Orthop. Dec 2001;120(6):639-647.

  • Enciso R, Nguyen M, Shigeta Y, Ogawa T, Clark GT. Comparison of cone-beam CT parameters and sleep questionnaires in sleep apnea patients and control subjects. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. Feb;109(2):285-293.

  • Ogawa T, Enciso R, Shintaku WH, Clark GT. Evaluation of cross-section airway configuration of obstructive sleep apnea. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. Jan 2007;103(1):102-108.

  • Tsuiki S, Almeida FR, Bhalla PS, AA AL, Fleetham JA. Supine-dependent changes in upper airway size in awake obstructive sleep apnea patients. Sleep Breath. Mar 2003;7(1):43-50.

  • Tsuiki S, Lowe AA, Almeida FR, Fleetham JA. Effects of an anteriorly titrated mandibular position on awake airway and obstructive sleep apnea severity. Am J Orthod Dentofacial Orthop. May 2004;125(5):548-555.

  • Lowe AA, Fleetham JA, Adachi S, Ryan CF. Cephalometric and computed tomographic predictors of obstructive sleep apnea severity. Am J Orthod Dentofacial Orthop. Jun 1995;107(6):589-595.

Medical and Sleep Disorder History

Medical History

  • Lin CM, Davidson TM, Ancoli-Israel S. Gender differences in obstructive sleep apnea and treatment implications. Sleep Med Rev. Dec 2008;12(6):481-496.

  • Lamm J, Poeschel J, Smith S. Obtaining a thorough sleep history and routinely screening for obstructive sleep apnea. J Am Acad Nurse Pract. Apr 2008;20(4):225-229.

Metabolic Syndrome

  • Levy P, Bonsignore MR, Eckel J. Sleep, sleep-disordered breathing and metabolic consequences. Eur Respir J. Jul 2009;34(1):243-260.

Hypertension

  • Parati G, Ongaro G, Bonsignore MR, Glavina F, Di Rienzo M, Mancia G. Sleep apnoea and hypertension. Curr Opin Nephrol Hypertens. Mar 2002;11(2):201-214.

Cardiovascular

  • Calvin AD, Somers VK. Obstructive sleep apnea and cardiovascular disease. Curr Opin Cardiol. Nov 2009;24(6):516-520.

  • Calvin AD, Albuquerque FN, Lopez-Jimenez F, Somers VK. Obstructive sleep apnea, inflammation, and the metabolic syndrome. Metab Syndr Relat Disord. Aug 2009;7(4):271-278.

  • Garvey JF, Taylor CT, McNicholas WT. Cardiovascular disease in obstructive sleep apnoea syndrome: the role of intermittent hypoxia and inflammation. Eur Respir J. May 2009;33(5):1195-1205.

Questionnaires:

  • Epworth
    Johns MW. A new method for measuring daytime sleepiness: the Epworth sleepiness scale. Sleep. Dec 1991;14(6):540-545.

  • Berlin
    Netzer NC, Stoohs RA, Netzer CM, Clark K, Strohl KP. Using the Berlin Questionnaire to identify patients at risk for the sleep apnea syndrome. Ann Intern Med. Oct 5 1999;131(7):485-491.

  • SF36
    McCallum J. The SF-36 in an Australian sample: validating a new, generic health status measure. Aust J Public Health. Apr 1995;19(2):160-166.

  • FOSQ
    Weaver TE, Laizner AM, Evans LK, et al. An instrument to measure functional status outcomes for disorders of excessive sleepiness. Sleep. Oct 1997;20(10):835-843.

  • Quality of Life
    Flemons WW. Measuring health related quality of life in sleep apnea. Sleep. Jun 15 2000;23Suppl 4:S109-114.

Review of Various Treatment Options, Oral Appliances and Surgical Therapy (as well as alternative procedures for initiating CPAP)

CPAP

  • McDaid C, Duree KH, Griffin SC, et al. A systematic review of continuous positive airway pressure for obstructive sleep apnoea-hypopnoea syndrome. Sleep Med Rev. Dec 2009;13(6):427-436.

  • Kushida CA, Littner MR, Hirshkowitz M, et al. Practice parameters for the use of continuous and bilevel positive airway pressure devices to treat adult patients with sleep-related breathing disorders. Sleep. Mar 1 2006;29(3):375-380.

  • Barnes M, Houston D, Worsnop CJ, et al. A randomized controlled trial of continuous positive airway pressure in mild obstructive sleep apnea. Am J Respir Crit Care Med. Mar 15 2002;165(6):773-780.

Weight Loss

  • Barnes M, Goldsworthy UR, Cary BA, Hill CJ. A diet and exercise program to improve clinical outcomes in patients with obstructive sleep apnea—a feasibility study. J Clin Sleep Med. Oct 15 2009;5(5):409-415.

Positional

  • Cartwright R, Ristanovic R, Diaz F, Caldarelli D, Alder G. A comparative study of treatments for positional sleep apnea. Sleep. Dec 1991;14(6):546-552.

Surgery

  • Practice parameters for the treatment of obstructive sleep apnea in adults: the efficacy of surgical modifications of the upper airway. Report of the American Sleep Disorders Association. Sleep 1996;19(2):152-155.

  • Sher AE, Schechtman KB, Piccirillo JF. The efficacy of surgical modifications of the upper airway in adults with obstructive sleep apnea syndrome. Sleep 1996;19(2):156-177. (Lit review)

  • Won CH, Li KK, Guilleminault C. Surgical treatment of obstructive sleep apnea: upper airway and maxillomandibular surgery. Proceedings of the American Thoracic Society 2008;5:193-199.

  • Prinsell JR. Maxillomandibular advancement surgery in a site-specific treatment approach for obstructive sleep apnea in 50 consecutive patients. Chest 1999;116(6):1519-1529.

  • Hendler BH, Costello BJ, Silverstein K, Yen D, Goldberg A. A protocol for uvulopalatopharyngoplsty, mortised genioplasty, and maxillomandibular advancement in patients with obstructive sleep apnea: an analysis of 40 cases. J Oral Maxillofac Surg 2001;59:892-897.

Selection of Oral Appliances for Patients, Oral Appliances vs. CPAP on Various Anatomic, Behavioral and Physiological Parameters
  • Gagnon Y, Mayer P, Morisson F, Rompre PH, Lavigne GJ. Aggravation of respiratory disturbances by the use of an occlusal splint in apneic patients: a pilot study. Int J Prosthodont. Jul-Aug 2004;17(4):447-453.

  • Ohayon MM, Li KK, Guilleminault C. Risk factors for sleep bruxism in the general population. Chest. Jan 2001;119(1):53-61.

  • Hoekema A, Stegenga B, De Bont LG. Efficacy and co-morbidity of oral appliances in the treatment of obstructive sleep apnea-hypopnea: a systematic review. Crit Rev Oral Biol Med. 2004;15(3):137-155.

APPLIANCE SELECTION:

OA Designs

  • Barthlen GM, Brown LK, Wiland MR, Sadeh JS, Patwari J, Zimmerman M. Comparison of three oral appliances for treatment of severe obstructive sleep apnea syndrome. Sleep Med. Oct 1 2000;1(4):299-305.

  • Deane SA, Cistulli PA, Ng AT, Zeng B, Petocz P, Darendeliler MA. Comparison of mandibular advancement splint and tongue stabilizing device in obstructive sleep apnea: a randomized controlled trial. Sleep. May 1 2009;32(5):648-653.

  • Gauthier L, Laberge L, Beaudry M, Laforte M, Rompre PH, Lavigne GJ. Efficacy of two mandibular advancement appliances in the management of snoring and mild-moderate sleep apnea: a cross-over randomized study. Sleep Med. Mar 2009;10(3):329-336.

Differences between Appliances

  • Ghazal A, Sorichter S, Jonas I, Rose EC. A randomized prospective long-term study of two oral appliances for sleep apnoea treatment. J Sleep Res. Sep 2009;18(3):321-328.

  • Hans MG, Nelson S, Luks VG, Lorkovich P, Baek SJ. Comparison of two dental devices for treatment of obstructive sleep apnea syndrome (OSAS). Am J Orthod Dentofacial Orthop. May 1997;111(5):562-570.

Vertical Opening

  • Pitsis AJ, Darendeliler MA, Gotsopoulos H, Petocz P, Cistulli PA. Effect of vertical dimension on efficacy of oral appliance therapy in obstructive sleep apnea. Am J Respir Crit Care Med. Sep 15 2002;166(6):860-864.

Boil and Bite

  • Vanderveken OM, Devolder A, Marklund M, et al. Comparison of a custom-made and a thermoplastic oral appliance for the treatment of mild sleep apnea. Am J Respir Crit Care Med. Jul 15 2008;178(2):197-202.

OAT versus CPAP

  • Barnes M, McEvoy RD, Banks S, et al. Efficacy of positive airway pressure and oral appliance in mild to moderate obstructive sleep apnea. Am J Respir Crit Care Med. Sep 15 2004;170(6):656-664.

  • Clark GT, Blumenfeld I, Yoffe N, Peled E, Lavie P. A crossover study comparing the efficacy of continuous positive airway pressure with anterior mandibular positioning devices on patients with obstructive sleep apnea. Chest. Jun 1996;109(6):1477-1483.

  • Engleman HM, McDonald JP, Graham D, et al. Randomized crossover trial of two treatments for sleep apnea/hypopnea syndrome: continuous positive airway pressure and mandibular repositioning splint. Am J Respir Crit Care Med. Sep 15 2002;166(6):855-859.

  • Ferguson KA, Ono T, Lowe AA, al-Majed S, Love LL, Fleetham JA. A short-term controlled trial of an adjustable oral appliance for the treatment of mild to moderate obstructive sleep apnoea. Thorax. Apr 1997;52(4):362-368.

  • Ferguson KA, Ono T, Lowe AA, Keenan SP, Fleetham JA. A randomized crossover study of an oral appliance vs nasal-continuous positive airway pressure in the treatment of mild-moderate obstructive sleep apnea. Chest. May 1996;109(5):1269-1275.

  • Hoekema A, Stegenga B, Bakker M, et al. Simulated driving in obstructive sleep apnoea-hypopnoea; effects of oral appliances and continuous positive airway pressure. Sleep Breath. Sep 2007;11(3):129-138.

Proper Fitting Techniques for Oral Appliances

Proper Fitting Techniques

  • Almeida FR, Lowe AA. Principles of oral appliance therapy for the management of snoring and sleep disordered breathing. Oral Maxillofac Surg Clin North Am. Nov 2009;21(4):413-420.

  • Kushida CA, Morgenthaler TI, Littner MR, et al. Practice parameters for the treatment of snoring and Obstructive Sleep Apnea with oral appliances: an update for 2005. Sleep. Feb 1 2006;29(2):240-243.

Treatment Plan and Informed Consent for Patients as well as Indications, Contraindications, Possible Complications and Side Effects Associated with Appliance Use

Indications

  • Kushida CA, Morgenthaler TI, Littner MR, et al. Practice parameters for the treatment of snoring and Obstructive Sleep Apnea with oral appliances: an update for 2005. Sleep. Feb 1 2006;29(2):240-243.

Contraindications

  • de Almeida FR, Bittencourt LR, de Almeida CI, Tsuiki S, Lowe AA, Tufik S. Effects of mandibular posture on obstructive sleep apnea severity and the temporomandibular joint in patients fitted with an oral appliance. Sleep. Aug 1 2002;25(5):507-513.

  • Cunali PA, Almeida FR, Santos CD, Nascimento LS, Valgrighi, NY, Tufik, S, Bittencourt, LRA. Influence in quality of life and efficacy of support therapy for TMD as an adjunct therapy for OA treatment. Sleep and Breathing. 2008;12(4):408.

  • Gagnon Y, Mayer P, Morisson F, Rompre PH, Lavigne GJ. Aggravation of respiratory disturbances by the use of an occlusal splint in apneic patients: a pilot study. Int J Prosthodont. Jul-Aug 2004;17(4):447-453.

APPLIANCE SELECTION:

OA Designs

  • Barthlen GM, Brown LK, Wiland MR, Sadeh JS, Patwari J, Zimmerman M. Comparison of three oral appliances for treatment of severe obstructive sleep apnea syndrome. Sleep Med. Oct 1 2000;1(4):299-305.

  • Bloch KE, Iseli A, Zhang JN, et al. A randomized, controlled crossover trial of two oral appliances for sleep apnea treatment. Am J Respir Crit Care Med. Jul 2000;162(1):246-251.

Differences between Appliances

  • Bloch KE, Iseli A, Zhang JN, et al. A randomized, controlled crossover trial of two oral appliances for sleep apnea treatment. Am J Respir Crit Care Med. Jul 2000;162(1):246-251.

  • Gauthier L, Laberge L, Beaudry M, Laforte M, Rompre PH, Lavigne GJ. Efficacy of two mandibular advancement appliances in the management of snoring and mild-moderate sleep apnea: a cross-over randomized study. Sleep Med. Mar 2009;10(3):329-336.

  • Ghazal A, Sorichter S, Jonas I, Rose EC. A randomized prospective long-term study of two oral appliances for sleep apnoea treatment. J Sleep Res. Sep 2009;18(3):321-328.

TMJ and OAT

  • Cunali PA, Almeida FR, Santos CD, et al. Prevalence of temporomandibular disorders in obstructive sleep apnea patients referred for oral appliance therapy. J Orofac Pain. Fall 2009;23(4):339-344.

  • Giannasi LC, Almeida FR, Magini M, et al. Systematic assessment of the impact of oral appliance therapy on the temporomandibular joint during treatment of obstructive sleep apnea: long-term evaluation. Sleep Breath. Nov 2009;13(4):375-381.

  • de Almeida FR, Lowe AA, Tsuiki S, et al. Long-term compliance and side effects of oral appliances used for the treatment of snoring and obstructive sleep apnea syndrome. J Clin Sleep Med. Apr 15 2005;1(2):143-152.

  • Almeida FR, Lowe AA, Sung JO, Tsuiki S, Otsuka R. Long-term sequellae of oral appliance therapy in obstructive sleep apnea patients: Part 1. Cephalometric analysis. Am J Orthod Dentofacial Orthop. Feb 2006;129(2):195-204.

Side Effects

  • de Almeida FR, Bittencourt LR, de Almeida CI, Tsuiki S, Lowe AA, Tufik S. Effects of mandibular posture on obstructive sleep apnea severity and the temporomandibular joint in patients fitted with an oral appliance. Sleep. Aug 1 2002;25(5):507-513.

  • Giannasi LC, Almeida FR, Magini M, et al. Systematic assessment of the impact of oral appliance therapy on the temporomandibular joint during treatment of obstructive sleep apnea: long-term evaluation. Sleep Breath. Nov 2009;13(4):375-381.

  • de Almeida FR, Lowe AA, Tsuiki S, et al. Long-term compliance and side effects of oral appliances used for the treatment of snoring and obstructive sleep apnea syndrome. J Clin Sleep Med. Apr 15 2005;1(2):143-152.

  • Almeida FR, Lowe AA, Otsuka R, Fastlicht S, Farbood M, Tsuiki S. Long-term sequellae of oral appliance therapy in obstructive sleep apnea patients: Part 2. Study-model analysis. Am J Orthod Dentofacial Orthop. Feb 2006;129(2):205-213.

  • Marklund M. Predictors of long-term orthodontic side effects from mandibular advancement devices in patients with snoring and obstructive sleep apnea. Am J Orthod Dentofacial Orthop. Feb 2006;129(2):214-221.

Long-term Follow-Up Care Including Compliance, Appliance Stability and Care, Effectiveness of Therapy and Side Effects
  • Cartwright RD. Effect of sleep position on sleep apnea severity. Sleep. 1984;7(2):110-114.

  • Meoli AL, Rosen CL, Kristo D, et al. Nonprescription treatments of snoring or obstructive sleep apnea: an evaluation of products with limited scientific evidence. Sleep. Aug 1 2003;26(5):619-624.

  • Chan AS, Lee RW, Cistulli PA. Dental appliance treatment for obstructive sleep apnea. Chest. Aug 2007;132(2):693-699.

  • Hoekema A, Stegenga B, De Bont LG. Efficacy and co-morbidity of oral appliances in the treatment of obstructive sleep apnea-hypopnea: a systematic review. Crit Rev Oral Biol Med. 2004;15(3):137-155.

Portable Monitoring Devices in Oral Appliance Therapy

Portable Monitors

  • Levendowski DJ, Morgan TD, Patrickus JE, et al. In-home evaluation of efficacy and titration of a mandibular advancement device for obstructive sleep apnea. Sleep Breath. Sep 2007;11(3):139-147.

  • Chesson AL, Jr., Berry RB, Pack A. Practice parameters for the use of portable monitoring devices in the investigation of suspected obstructive sleep apnea in adults. Sleep. Nov 1 2003;26(7):907-913.

  • Collop NA, Anderson WM, Boehlecke B, et al. Clinical guidelines for the use of unattended portable monitors in the diagnosis of obstructive sleep apnea in adult patients. Portable Monitoring Task Force of the American Academy of Sleep Medicine. J Clin Sleep Med. Dec 15 2007;3(7):737-747.

Oral Appliance Titration

Clinical

  • Ferguson KA, Cartwright R, Rogers R, Schmidt-Nowara W. Oral appliances for snoring and obstructive sleep apnea: a review. Sleep. Feb 1 2006;29(2):244-262.

  • Almeida FR, Lowe AA. Principles of oral appliance therapy for the management of snoring and sleep disordered breathing. Oral Maxillofac Surg Clin North Am. Nov 2009;21(4):413-420.

Overnight

  • de Almeida FR, Bittencourt LR, de Almeida CI, Tsuiki S, Lowe AA, Tufik S. Effects of mandibular posture on obstructive sleep apnea severity and the temporomandibular joint in patients fitted with an oral appliance. Sleep. Aug 1 2002;25(5):507-513.

  • Petelle B, Vincent G, Gagnadoux F, Rakotonanahary D, Meyer B, Fleury B. One-night mandibular advancement titration for obstructive sleep apnea syndrome: a pilot study. Am J Respir Crit Care Med. Apr 15 2002;165(8):1150-1153.

Children

Diagnosis

  • Schechter MS. Technical report: diagnosis and management of childhood obstructive sleep apnea syndrome. Pediatrics. Apr 2002;109(4):e69.

  • Urschitz MS, Guenther A, Eggebrecht E, et al. Snoring, intermittent hypoxia and academic performance in primary school children. Am J Respir Crit Care Med. Aug 15 2003;168(4):464-468.

Craniofacial

  • Rosen CL, D'Andrea L, Haddad GG. Adult criteria for obstructive sleep apnea do not identify children with serious obstruction. Am Rev Respir Dis. Nov 1992;146(5 Pt 1):1231-1234.

  • Ozdemir H, Altin R, Sogut A, et al. Craniofacial differences according to AHI scores of children with obstructive sleep apnoea syndrome: cephalometric study in 39 patients. Pediatr Radiol. May 2004;34(5):393-399.

  • Schiffman PH, Rubin NK, Dominguez T, et al. Mandibular dimensions in children with obstructive sleep apnea syndrome. Sleep. Aug 1 2004;27(5):959-965.

Treatments

  • Schechter MS. Technical report: diagnosis and management of childhood obstructive sleep apnea syndrome. Pediatrics. Apr 2002;109(4):e69.

  • Marcus CL, Ward SL, Mallory GB, et al. Use of nasal continuous positive airway pressure as treatment of childhood obstructive sleep apnea. J Pediatr. Jul 1995;127(1):88-94.

  • Hultcrantz E, Larson M, Hellquist R, Ahlquist-Rastad J, Svanholm H, Jakobsson OP. The influence of tonsillar obstruction and tonsillectomy on facial growth and dental arch morphology. Int J Pediatr Otorhinolaryngol. Sep 1991;22(2):125-134.

  • Linder-Aronson S. Effects of adenoidectomy on dentition and nasopharynx. Trans Eur Orthod Soc. 1972:177-186.

Orthodontics/OAT

  • Cozza P, Ballanti F, Prete L. A modified monobloc for treatment of young children with obstructive sleep apnea. J Clin Orthod. Apr 2004;38(4):241-247.

  • Villa MP, Malagola C, Pagani J, et al. Rapid maxillary expansion in children with obstructive sleep apnea syndrome: 12-month follow-up. Sleep Med. Mar 2007;8(2):128-134.

  • Pirelli P, Saponara M, Guilleminault C. Rapid maxillary expansion in children with obstructive sleep apnea syndrome. Sleep. Jun 15 2004;27(4):761-766.

Recommended Textbooks:
  1. Craniofacial Pain: A Handbook for Assessment, Diagnosis & Management, American Academy of Craniofacial Pain
  2. Sleep Medicine for Dentists, Lavigne, Cistulli & Smith
  3. Dental Clinics of North America 2012, Vol 56, Sleep Medicine & Dentistry
  4. Role of Dentistry in Sleep Apnea by Dr. Garry

All Textbooks are available at TM Data Resources: 505-332-1400