A study by Drs. Nancy Proano Wise, Donald Rinchuse, and Daniel Rinchuse
The aim of this study was to survey ortho-dontic clinicians on the topic of centric bite registrations. Specifically, this study surveyed 1) who is/are the person(s) taking the bite registrations in United States orthodontic practices, 2) the methods being used to record the bite, 3) whether or not the same method is being used for facial photographs and lateral cephalograms, and 4) whether or not the person taking the bite registration is the same person taking the facial photos and lateral cepahologram.
An email invitation from the American Association of Orthodontists (AAO) Partners in Education was sent to a random sample of the members of the AAO (n = 2,300), requesting participation in a 10-question online survey (SurveyMonkey®) regarding centric bite registrations. A total of 166 orthodontists participated in the survey.
According to the survey, the majority of the orthodontists (92%) said they do take a bite registration as part of their ortho-dontic records. However, there seems to be little consistency among orthodontists in regards to the method used or who actually takes the bite registration. Most of the respondents (39%) said when they take a bite registration, they simply tell the patient to bite down on their back teeth, and the orthodontic assistant is usually the person in charge of recording the bite. The majority of the respondents (about 64%) said that the same bite method that is used for the bite registration is also used for the facial photographs and the cephalogram. When asked if the same person that records the bite is also the same person who takes the rest of the records, 45% said that only sometimes the same person takes all the records, and 42% said that they always have the same person taking all the records.
Uses and methodologies for bite registrations vary among orthodontic practitioners. Persons taking the bite registration differ (orthodontist versus assistant versus other) as well as whether or not the same bite registration is used for photos and lateral cephalograms. Inconsistencies were also found as to who takes all records.
Over the past century, the definition of centric relation (CR) has changed multiple times, and several philosophies have developed regarding the “proper” definition and “correct” recording technique. The inconsistency among the different schools of thought seems to make the topic of CR a continuous debate. The American Board of Orthodontics is equivocal and does not currently provide any guidelines regarding what is the correct method to take a bite registration, who should be taking it, and whether or not that same bite relationship should be used for patient photos and lateral cephalogram.
Orthodontic records are taken for the purpose of diagnosis and treatment planning orthodontic patients. Most commonly these records include a clinical exam, diagnostic study models, intraoral and extraoral photographs, a panoramic radiograph, and a lateral cephalogram.1 Another diagnostic tool, not mentioned in the list above, is the bite registration. The bite registration is an optional orthodontic record. Some practitioners do not use the bite registration because they do not feel it provides unique information for diagnosis and treatment planning. Some practitioners view the bite registrations to be one of the most important tools in ortho-dontic diagnosis.
There are at least six occlusal philosophies in dentistry: 1) classic gnathology, 2) bioesthetic dentistry, 3) Dawson/Pankey, 4) the neuromuscular school (LVI), 5) the Roth orthodontic gnathologic view, and 6) the nongnathologic view. The main difference among the above schools of thought is how CR is recorded. There are also various philosophies concerning manipulation techniques to record CR, deprogramming, and whether to use a facebow or an earbow transfer.
Most CR records are dentist-manipulated, and there are differences in findings from manipulated an unmanipulated CR recordings. Dentist-manipulated CR records are considered to be more reliable but less valid and physiological than patient-manipulated records.2-11 A contemporary thought is that recording a retruded CR would make sense for only denture fabrication when no inter-occlusal reference is possible.
Contemporary gnathologic orthodontists recommend articulator-mounted dental casts mounted in anterior-superior CR in order to establish coincidence of MI (maximum intercuspation)-CR.3-4 They believe that the only way to recognize MI-CR discrepancies is via articulator-mounted casts, not via hand-held casts.5 Orthodontic gnathologists believe it is possible to assess a three-dimensional condylar position through the use of the Roth power centric bite registration with articulator-mounted dental casts.6-15,18,20-21 The belief is that it is possible to locate a particular position of the condyle precisely in the glenoid fossa via CR recordings and that the power centric will seat the condyles in the optimal, anterior-superior CR position. This approach also advocates using the terminal hinge axis position, the need for pretreatment MI-CR converted lateral cephalograms, and placing a gnathologic positioner immediately after orthodontic appliances are removed.6
On the other hand, nongnathologic orthodontists tend to use hand-held dental casts and non-instrument-oriented techniques. Their focus is on achieving the best occlusal relationship within the framework of optimal dentofacial esthetics, function, and stability. They also believe that MI-CR does not have to be coincident, and that there is a tolerance for slides up to 2 mm-4 mm in the horizontal plane with little or no attention given to the relevance of the vertical and transverse planes.7,8 Parenthetically, the gnathologists believe that the tolerance for MI-CR discrepancies is 1.5 mm in the horizontal and vertical planes and 0.5 mm in the transverse plane.
The purpose of this study is to survey orthodontists throughout the United States to assess 1) who is the person taking the bite registrations in their practices, 2) the exact method being used to record the bite, 3) whether or not the same method is being used for facial photographs and lateral cephalogram, and 4) whether or not the person taking the bite registration is also the same person taking the facial photos and lateral cepahologram.
Materials and methods
A 10-question survey was sent to a randomized sample of orthodontists across the United States via three email blasts through the AAO. Orthodontic residents and faculty at a university program worked concomitantly to develop this 10-question survey. The survey consisted of seven questions pertaining to orthodontic records and bite registrations and three demographic questions.
A finalized copy of the 10-question survey was generated using SurveyMonkey. The survey was then forwarded to the AAO for approval. A finalized survey tool was created using SurveyMonkey. The AAO then sent out an email, including a link to the survey, to a random sample of 2,300 of its members. A letter was distributed with the survey asking for participation as well as an agreement to participate.
The survey link was first sent out on January 12, 2015. Then to increase participation, a second and third email was sent on February 23, 2015, and April 22, 2015, to the surveyed population. After data collection, the survey instrument was utilized to compile responses into useful figures and charts.
Of the 2,300 emails sent out to a random sample of orthodontists who are members of the AAO, 166 participated in the survey, amounting to a response rate of approximately 7.2%. The survey was completely anonymous. The important findings from the survey are shown in Table 1.
As far as the different philosophies on occlusion, there was little consistency among the respondents as to which philosophy they believe in. Most respondents (44%) said they follow classic gnathology; 31% said they follow the nongnathologic philosophy; 14% said they follow the Dawson/Pankey philosophy; 9% said they follow the Roth gnathologic view; 6% said they follow bio-esthetic dentistry, and 6% said they follow the neuromuscular school of thought.
The majority of the respondents (92%) said they do take a bite registration as part of their orthodontic records. There was a small number (8%) of orthodontists who said they do not take a bite registration as part of their orthodontic records. However, there seems to be little consistency among orthodontists in regard to the method used or to who actually takes the bite registration. The majority of the respondents (39%) said, when taking a bite registration, they simply tell the patients to bite down on their back teeth. About 28% said they tell the patients to touch the roof of their mouth with the tip of their tongue and bite down; 23% said they use the bimanual manipulation technique; 5% said they use the Roth power bite technique; 7% said they use some other technique that was not listed in the answer choices, and 8% said that do not take a bite registration as part of their orthodontic records.
The majority of the respondents (52%) said their assistant(s) is/are the person(s) responsible for recording the bite registration, whereas 36% said they themselves (the orthodontists) record the bite. However, when asked if the same person that records the bite is also the same person who takes the rest of the records, 45% said that only sometimes the same person takes all the records, and 42% said that they always have the same person taking all the records. That being said, the majority of the respondents (63%-65%) said that the same bite that is used for the bite registration is also used for the facial photographs and the cephalogram.
The results of this survey demonstrate that the majority of orthodontists are using bite registrations as part of their orthodontic records. However, as has been in the past, there remain inconsistencies in agreement among one occlusal philosophy and on the methodologies used by orthodontists to determine a patient’s “true” bite. The topic of centric relation, therefore, will continue to be debatable.
The majority of the respondents (51.81%) said their assistant(s) is/are the person(s) responsible for recording the bite registration, whereas 35.54% said they themselves (the orthodontists) record the bite. However, when asked if the same person that records the bite is also the same person who takes the rest of the records, 45.18% said that only sometimes the same person takes all the records, and 41.57 % said that they always have the same person taking all the records. This could be misleading to an orthodontist who is looking at a set of records in which, for example, one assistant took a bite registration a certain way but another assistant took the cephalometric radiograph with the patient biting differently. That being said, the majority of the respondents (63%-65%) said that the same bite that is used for the bite registration is also used for the facial photographs and the cephalogram. To assure that the same bite is being used across the board, when multiple people are responsible for the records, it seems there would need to be a calibrated standard method for capturing the bite for any person in the office who is responsible for taking orthodontic records.
Does it matter if a bite registration is taken for initial records? Does it matter how it’s taken or who takes it? Does the information gained by taking a bite registration make any clinically significant impact on the final results of orthodontic treatment? Maybe, maybe not. One would think that since the majority of orthodontists are taking bite registrations as part of their orthodontic records, it must be a necessary diagnostic tool to plan a certain outcome. With all the debate still surrounding the topic of CR, no wonder the AAO is equivocal and does not currently provide any guidelines in regard to what is the “correct” method to take a bite registration, who should be taking it, and whether or not the bite relationship should be used for the patient photos and lateral or PA cephalogram.
Assuming that the small percentage of orthodontists who do not take bite registrations are getting acceptable orthodontic results, then maybe taking a bite registration is not a necessary step in orthodontic record taking. It would be interesting to know how many orthodontists actually look at and study their bite registrations when treatment planning a case versus how many just take them as a routine measure and never go back and look at them. In the latter of these two circumstances, it seems as though orthodontists could be spending excess money on overhead material and chairtime.
This survey has limitations. In the hierarchy of evidence, a survey typically falls on the lower end of the spectrum. Although a randomized clinical trial (RCT) appears to be the gold standard for obtaining information, the construction of an RCT may not always be feasible or appropriate for the type of research at hand. The information we are seeking in this particular study was best obtained via a survey. Another limiting factor of this survey is the low response rate. However, by surveying all orthodontic practitioners who are members of the AAO in the U.S., we were able to gain more information than if we had surveyed only a small sample of local/regional clinicians.
Based on a survey of 166 AAO member orthodontists on the topic of centric bite registration, the following conclusions have been reached.
- The major school of thought being followed by orthodontists is classic gnathology.
- Generally, the orthodontic assistant is the person taking the bite registration.
- The most common method for recording a bite registration was to tell the patient to bite down on their back teeth.
- Generally, the same bite that is used for the bite registration is also being used when taking the patient’s facial photographs and cephalogram.
- Of the orthodontists surveyed, 42% of them have the same person take all of the orthodontic records, and 45% of them said that only sometimes does the same person take all the records.
The authors of this article extend a special thank you to the surveyed members of the AAO who participated in this research topic.
- Dykhouse VJ, Moffitt AH, Grubb JE, Greco PM, English JD, Briss BS, Jamieson SA, Kastrop MC, Owens SE Jr. A revision of the adult intraoral radiograph protocol for ABO clinical examinations. Am J Orthod Dentofacial Orthop. 2007; 131(3):303-304.
- Helkimo M, Ingervall B, Carlsson GE. Comparison of different methods in active and passive recording of the retruded position of the mandible. Scand J Dent Res. 1973;81(4):265-271.
- Helkimo M, Ingervall B, Carlsson GE. Variation of retruded and muscular position of mandible under different recording conditions. Acta Odontol Scand. 1971;29(4):423-437.
- Helkimo M, Ingervall B, Carlsson GE. Recording of the retruded position of the mandible with application of varying external pressure to the lower jaw in man. Arch Oral Biol. 1971;16(10):1165-1171.
- Kantor ME, Silverman SI, Garfinkel L. Centric-relation recording techniques — a comparative investigation. J Prosthet Dent. 1972;28(6):593-600.
- Smith HF Jr. A comparison of empirical centric relation records with location of terminal hinge axis and apex of the gothic arch tracing. J Prosthet Dent. 1975;33(5):511-520.
- Shafagh I, Yoder JL, Thayer KE. Diurnal variance of centric relation position. J Prosthet Dent. 1975;34(5):574-582.
- Strohaver RA. A comparison of articulator mountings made with centric relation and myocentric position records. J Prosthet Dent. 1972;28(4):379-390.
- Long JH Jr. Location of the terminal hinge axis by intraoral means. J Prosthet Dent. 1970;23(1):11-24.
- Lundeen HC. Centric relation records: the effect of muscular action. J Prosthet Dent. 1974;31(3):244-253.
- Celenza FV. The centric position: replacement and character. J Prosthet Dent. 1973;30(4 Pt 2):591-598.
- Kulbersh R, Kaczynski R, Freeland T. Orthodontics and gnathology: introduction. Semin Orthod. 2003;9(2):93-95.
- Cordray FE. Centric relation treatment and articulator mountings in orthodontics. Angle Orthod. 1996;66(2):153-158.
- Klar NA, Kulbersh R, Freeland T, Kaczynski R. Maximum intercuspation-centric relation disharmony in 200 consecutively finished cases in a gnathologically oriented practice. Semin Orthod. 2003;9(2):109-116.
- Roth RH. Temporomandibular pain-dysfunction and occlusal relationships. Angle Orthod. 1973;43(2):136-153.
- Roth RH. The maintenance system and occlusal dynamics. Dent Clin North Am. 1976;20(4):761-788.
- Roth RH. Functional occlusion for the orthodontist. J Clin Orthod. 1981;15(1):32-51.
- Roth RH. Treatment mechanics for the straight-wire appliance. In: Graber TM, Swain BF, eds. Orthodontics, current principles and techniques. St. Louis: Mosby; 1985;665-716.
- Roth RH. Functional occlusion for the orthodontist. Part III. J Clin Orthod. 1981;15(3):174-9, 182-198.
- Hoffman PJ, Silverman SI, Garfinkel L. Comparison of condylar position in centric relation and in centric occlusion in dentulous subjects. J Prosthet Dent. 1973;30(4 Pt 2):582-588.
- Kulbersh R, Dhuta M, Navarro M, Kaczynski R. Condylar distraction effects of standard edgewise therapy versus gnathologically based edgewise therapy. Semin Orthod. 2003;9(2):117-127.
- Crawford SD. Condylar axis position, as determined by the occlusion and measured by the CPI instrument, and signs and symptoms of temporomandibular dysfunction. Angle Orthod. 1999;69(2):103-115.
- Utt TW, Meyers CE Jr, Wierzba TF, Hondrum SO. A three dimensional comparison of condylar position changes between centric relation and centric occlusion using the mandibular position indicator. Am J Orthod Dentofacial Orthop. 1995;107(3):298-308.
- Schmitt ME, Kulbersh R, Freeland T, Bever K, Pink FE. Reproducibility of the Roth power centric in determining centric relation. Semin Orthod. 2003;9(2):102-108.
- Lavine D, Kulbersh R, Bonner P, Pink FE. Reproducibility of the condylar position indicator. Semin Orthod. 2003;9(2):96-101.
- Rinchuse DJ. A three-dimensional comparison of condylar change between centric relation and centric occlusion using the mandibular position indicator. Am J Orthod Dentofacial Orthop. 1995;107(3):319-328
- Johnston LE Jr. Fear and loathing in orthodontics: notes on the death of theory. In: Carlson DS, Ferrara AM, eds. Craniofacial growth theory and orthodontic treatment. Ann Arbor, Mich.: Center for Human Growth and Development, University of Michigan; 1990:75-91.