Global Diagnosis E-Book

J. William Robbins

• Herausgeber: Quintessence Publishing Co, Inc
• Kategorie: Fachliteratur
• Sprache: Englisch

Seitenzahl: 250

Veröffentlichungsjahr: 2019

Beschreibung

Incisal edge position is often considered the most important factor when treating complex restorative patients, yet the incisal edges can be in a perfect position and the final result can still fail due to unacceptable gingival levels. The emphasis in the Global Diagnosis system is to determine the etiology of the aberrant gingival positions prior to treatment. The power of the system is that the diagnosis leads to the treatment plan. This book explains the Global Diagnosis system and shows how to diagnose and treat patients based on five CORE questions. Subsequent chapters outline treatment options. The final chapter challenges the reader to treatment plan cases based on the five questions and other diagnostic information. Included is a CD with the CORE template, which allows readers to input diagnostic photographs and information to facilitate record keeping.

Leseprobe

Global DiagnosisA New Vision of Dental Diagnosis and Treatment Planning

GLOBALDIAGNOSIS

A New Vision of Dental Diagnosisand Treatment Planning

J. William Robbins, DDS, MA

Adjunct ProfessorDepartment of Comprehensive DentistryThe University of Texas Health Science Centerat San Antonio Dental School

Private PracticeSan Antonio, Texas

Jeffrey S. Rouse, DDS

Clinical Adjunct Associate ProfessorDepartment of ProsthodonticsThe University of Texas Health Science Centerat San Antonio Dental School

Private Practice Limited to ProsthodonticsSan Antonio, Texas

Library of Congress Cataloging-in-Publication Data

Names: Robbins, J. William, author. | Rouse, Jeffrey S., author.

Title: Global diagnosis : a new vision of dental diagnosis and treatment

  planning / J. William Robbins, Jeffrey S. Rouse.

Other titles: New vision of dental diagnosis and treatment planning

Description: Hanover Park, IL : Quintessence Publishing Co, Inc., [2016]

|

  Includes bibliographical references.

Identifiers: LCCN 2015041375 | ISBN 9780867155235 | eISBN 9780867158595

Subjects: | MESH: Dental Restoration, Permanent--methods. | Patient Care

  Planning. | Oral Surgical Procedures. | Periodontal

Diseases--diagnosis. |

  Tooth Diseases--diagnosis.

Classification: LCC RK501 | NLM WU 300 | DDC 617.6/9--dc23

LC record available at http://lccn.loc.gov/2015041375

© 2016 Quintessence Publishing Co, Inc

Quintessence Publishing Co, Inc4350 Chandler DriveHanover Park, IL 60133www.quintpub.com

All rights reserved. This book or any part thereof may not be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, or otherwise, without prior written permission of the publisher.

Editor: Leah HuffmanDesign: Ted PeredaProduction: Kaye Clemens

Contents

Dedication

Preface

About the Authors

Contributors

1

Global Diagnosis: The Art and Science of Interdisciplinary Treatment Planning

2

Global Analysis Diagnosis Form

3

The Five CORE Questions

4

Esthetic Crown Lengthening Surgery

5

Tissue Grafting

6

Dentoalveolar Intrusion of the Adult Dentition

7

Forced Eruption

8

Orthognathic Surgery

9

Dental Facial Plastics

10

Dentoalveolar Extrusion: The Most Difficult Global Diagnosis

11

Sequencing the Treatment Plan

12

The CORE Template

13

Case Studies

Index

Dedication

To my favorite kids—Alyssa, Sarah, Andrew, and PatrickandTo the love of my life for more than 35 years, my wife and best friend, Brenda

–JWR

To my wife, Lisa, who provides serenity to our family through her wisdom and love, thank you for relinquishing your dreams for mine and ours.

To my kids—Sydney, Zachary, and Jake. Few children in the world can identify the proper “Global” diagnosis for the gummy smile of waiters by the age of 10. I hope that skill serves you well in life! Love y’all.

And, finally, to Bill Robbins. I hope this book confers a legacy to the greatest teacher and person I have ever known. No moment impacted my life morethan when you agreed to mentor me and bring me into your world.

–JSR

Preface

Global Diagnosis is a story of mentorship and friendship. We first met when Jeff was a dental student and Bill was a full-time faculty member, so our relationship started as a student/mentor relationship. Jeff completed a 2-year general practice residency and returned to full-time private practice in San Antonio. After a few years in practice, Jeff urged Bill to leave academics and to join Jeff’s practice. That is when our friendship began.

We practiced together for several years, and professionally it was a very rich time for both of us. We grew a lot as individuals and as colleagues. We also began teaching and lecturing together. This was the genesis of our teaching partnership, CORE Dentistry, which is still alive and well today. After a few years, we separated our practices as Jeff pursued graduate training in prosthodontics and Bill started his solo private practice. However, we continued to learn and teach together. We shared the goal of providing high-level interdisciplinary dentistry to our patients. To that end, we attended a lot of continuing education. Our dentistry and our teaching were impacted significantly by a group of teachers who were groundbreakers in the areas of esthetic and interdisciplinary dentistry. These included John Kois, Frank Spear, Vince Kokich, Pat Allen, Gerry Chiche, Bob Cronin, Jim Summitt, Burt Melton, and Jim Kessler. We both feel blessed that these iconic teachers have become our friends. Those of you who are familiar with their work will see their fingerprints throughout our book. Once again, what started as a student/mentor relationship has ended in lifelong friendships.

Through our years of treating complex restorative patients, we have come to believe that the parameter that makes these cases interdisciplinary is the patient’s aberrant gingival levels. In our early years of treatment planning these patients, the emphasis was on the incisal edge position of the maxillary central incisors. We still put a great deal of emphasis on the incisal edge position, yet the incisal edges can be in a perfect position and the final treatment result a failure due to unacceptable gingival levels. Therefore, the emphasis in our Global Diagnosis system is to determine the etiology of the aberrant gingival positions. Once the etiology is determined, there are only a limited number of treatment options to correct the discrepancy. That is the power of the system: The diagnosis leads to the treatment plan.

Our Global Diagnosis system is based on five CORE questions:

1. What are the facial proportions and skeletal relationships?

2. What are the length and mobility of the upper lip?

3. What is the relationship between the gingival line and the horizon?

4. What is the length of the maxillary central incisor?

5. Is the CEJ palpable in the gingival sulcus?

This book outlines how to use these questions to determine a diagnosis and includes chapters on the treatment options available for various diagnoses, including crown lengthening, tissue grafting, intrusion, forced eruption, orthognathic surgery, facial plastics, and extrusion. Chapter 12 describes our CORE template, which is included on the attached CD, and how to use thirteen photographs to complete the template. This template can be used for presentations for dental study clubs as well as to keep track of pertinent information. In the final chapter, we invite readers to plan the treatment for five case studies based on the CORE questions and other diagnostic information.

The Global Diagnosis system, which we share with you, would not have been possible without those who came before us. To our teachers, to the teachers who taught them, to all of the links in the chain, we raise our glasses.

Acknowledgments

We would like to thank the following people for their contributions:

John Bonfardeci

Bloyce Britton, DDS

Danny Diebel, CDT

Jay Gibson, DDS

Dickie Jowdy

Kenneth Krueger, DDS

Dene Lebeau, CDT, & Lebeau Dental Lab

Steve McGowan, CDT, & Arcus Laboratory

Robert Norris, DDS

Eric Rindler, DDS

Sabina Sanders, CDT

Richard Schwartz, DDS

James Startzell, DMD

B. D. Tiner, DDS, MD

Gilbert Young, CDT

About the Authors

J. William Robbins, DDS, MA, maintains a full-time private practice in San Antonio, Texas, and is an adjunct professor in the Department of Comprehensive Dentistry at the University of Texas Health Science Center at San Antonio Dental School. He has published over 80 articles, abstracts, and chapters on a wide range of dental subjects and has lectured worldwide. He coedited a textbook, Fundamentals of Operative Dentistry: A Contemporary Approach, which is now in its fourth edition (Quintessence, 2013). He has won several awards, including the Presidential Teaching Award at the University of Texas Health Science Center and the 2002 Texas Dentist of the Year Award. Dr Robbins is a diplomate of the American Board of General Dentistry and past president of the American Board of General Dentistry, the Academy of Operative Dentistry, the Southwest Academy of Restorative Dentistry, and the American Academy of Restorative Dentistry.

Jeffrey S. Rouse, DDS, maintains a full-time private practice in San Antonio, Texas, and is a clinical adjunct associate professor in the Department of Prosthodontics at the University of Texas Health Science Center at San Antonio Dental School. He is a member of the American Academy of Restorative Dentistry and the American College of Prosthodontists and past president of the Southwest Academy of Restorative Dentistry. Dr Rouse has written numerous journal articles, including a portion of the “Annual Review of Selected Dental Literature” published each summer in the Journal of Prosthetic Dentistry. In addition, he has contributed chapters on porcelain veneers and anterior ceramic crowns to three editions of a dental textbook. Dr Rouse lectures nationally and internationally on a wide variety of topics ranging from dental esthetics to sleep prosthodontics.

Contributors

Edward P. Allen,DDS, PhD

Director

Center for Advanced Dental Education

Dallas, Texas

Marco A. Brindis,DDS

Assistant Professor of Clinical Prosthodontics

Interim Chair, Department of Prosthodontics

Louisiana State University School of Dentistry

New Orleans, Louisiana

Bloyce H. Britton III,DDS

Clinical Instructor in Orthodontics

The University of Texas Health Science Center at San Antonio Dental School

Private Practice Limited to Orthodontics

San Antonio, Texas

Jay Gibson,DDS

Associate Professor

Department of Developmental Dentistry

Division of Orthodontics

The University of Texas Health Science Center at San Antonio Dental School

Private Practice Limited to Orthodontics and Dentofacial Orthopedics

San Antonio, Texas

J. William Robbins,DDS, MA

Adjunct Professor

Department of Comprehensive Dentistry

The University of Texas Health Science Center at San Antonio Dental School

Private Practice

San Antonio, Texas

Jeffrey S. Rouse,DDS

Clinical Adjunct Associate Professor

Department of Prosthodontics

The University of Texas Health Science Center at San Antonio Dental School

Private Practice Limited to Prosthodontics

San Antonio, Texas

Lisa D. Rouse,DDS

Private Practice

San Antonio, Texas

Joseph E. Van Sickels,DDS

Assistant Dean of Hospital Dentistry

Professor of Oral and Maxillofacial Surgery

College of Dentistry

University of Kentucky

Lexington, Kentucky

1

Global Diagnosis: The Art and Science of Interdisciplinary Treatment Planning

This chapter compares the traditional and contemporary approaches to diagnosis and treatment planning and offers an alternative, global approach.

Traditional Approach to Diagnosis and Treatment Planning: Occlusal Relationships

With an increased emphasis on interdisciplinary treatment planning in recent years, the deficiencies associated with traditional methods of diagnosis and treatment planning have become more evident and problematic. Historically, sophisticated, comprehensive diagnosis and treatment planning was based on an occlusally driven philosophy. The traditional data-collection process included, but was not limited to, a social history, a medical history, a determination of the patient’s chief complaint, a past dental history, charting of missing teeth, charting of existing restorations, charting of defective restorations and caries, periodontal charting, vitality testing, cancer screening examination, occlusal examination, temporomandibular joint and muscle examination, a complete series of radiographs, diagnostic photographs, and study casts mounted on an articulator in a predetermined position.

Once this enormous amount of data was gathered, the dentist would then complete a risk assessment associated with each of the areas of collected data. The dentist then made a diagnosis of each tooth based on the data. This diagnosis may have been related to the pulpal health, the periodontal health, and/or the restorability of the tooth. Additionally, the mounted casts were used to evaluate tooth-to-tooth and arch-to-arch relationships. If required, a diagnostic wax-up was accomplished, based on the occlusal evaluation. The treatment plan was simply based on restorative space, anterior guidance, and resistance and retention form of the final preparations, with no focus on placing the teeth in the correct position in the face.

Once this process was completed, the next step was to create a sequenced treatment plan. However, because of the sheer amount of data, the dentist was often overwhelmed and therefore unable to develop a sequenced treatment plan. The dentist literally did not know where to start. The problem with this traditional approach is that there are many “regional” diagnoses made (ie, pulpal status of the maxillary first premolar) but no “global” diagnosis (ie, where the teeth fit into the patient’s mouth and face). The dentist gets lost in all of the details.

In medicine, the approach is different. When a patient presents with a chief complaint, a history is taken to determine the nature and duration of the complaint. Any systemic conditions such as hypertension are also noted in the history. Specific diagnostic tests are ordered and evaluated based on the chief complaint. Based on the collected data, the next step is to make a diagnosis. If the diagnosis is cancer, for example, then the treatment plan is based on the type and stage of the malignancy. The patient will receive either chemotherapy, radiation therapy, surgery, or a combination approach. However, if the diagnosis is a localized condition, the treatment plan will be completely different. The treatment plan is based on the global diagnosis, not the initial symptoms. If the patient has any systemic conditions such as hypertension, they are considered regional diagnoses. They may be important and may impact the final treatment plan, but they do not dictate the plan.

In medicine, therefore, the sequence is (1) data collection, (2) global diagnosis (perhaps modified by regional diagnoses), (3) treatment plan, whereas in dentistry the sequence is (1) data collection, (2) regional diagnoses, (3) treatment plan. In dentistry, a global diagnosis would determine where the teeth and gingiva should be placed in the patient’s mouth and face, but it is impossible to make this determination using regional diagnoses alone. The dentist is expected to make a global treatment plan based on a lot of regional diagnoses.

Decades ago, the traditional style of regional treatment planning was effective because treatment options were very limited; the restorative dentist had few treatment modalities in addition to tooth preparation. At that time in history, the primary tools available for treating the complex restorative patient were functional crown lengthening surgery and increasing the vertical dimension of occlusion. Practitioners did not have access to advanced periodontal therapies. Predictable root coverage with grafting procedures had not been discovered. Additionally, esthetic crown lengthening surgery had not been described and was not used routinely to treat altered passive eruption.

Orthodontic treatment was primarily for the adolescent patient and was used infrequently with the adult patient. It was seldom a part of a comprehensive treatment plan in an adult patient because there was no emphasis on orthodontic intrusion and extrusion of teeth to enhance the restorative treatment plan. Oral surgery had nothing to offer the restorative dentist other than tooth extraction. More sophisticated maxillofacial surgical procedures were used primarily to treat the trauma patient. Finally, the use of plastic surgery procedures to enhance a comprehensive dental treatment plan had not even been conceived.

Contemporary Approach to Diagnosis and Treatment Planning: Tooth Position

This all changed in the early 1980s. Two young prosthodontists, John Kois and Frank Spear, challenged the traditional approach to prosthodontic treatment planning. With the advanced treatment modalities offered by orthodontics, periodontics, and oral and maxillofacial surgery, along with an increased emphasis on esthetics, they offered a new treatment-planning paradigm based on the belief that if the teeth were placed in the correct position in the patient’s face, effective function would follow. In other words, they began their treatment planning with tooth position rather than condylar position, hence their term facially generated diagnosis.

Along with many others in our profession, the authors embraced this new logical vision of treatment planning. Over the years, we developed a set of guidelines to help us determine the new incisal edge position of the maxillary anterior teeth as the starting point in treatment planning the interdisciplinary patient.

Establishing incisal edge position

Descriptive guidelines

• The incisal edges of the maxillary anterior teeth should be cradled by the lower lip in full smile.

• There should be a smooth continuation between the incisal edges of the maxillary anterior teeth and the buccal cusp tips of the maxillary posterior teeth with no step-up or step-down from front teeth to back teeth.

Confirmation guidelines

• The average incisal display of the maxillary central incisors in repose is 3 to 4 mm in the young female and 1 to 2 mm in the young male.1

• The average length of the maxillary central incisor is 10 to 11 mm.2

Using these guidelines, a new incisal edge position can be established by the dentist, although this is just a “best guess” based on the four guidelines. A diagnostic wax-up is then completed on the mounted study casts, and stents are fabricated for provisional restorations. After the teeth are prepared, the provisional restorations are placed according to the new proposed incisal edge position. Over the next several days, the patient can dynamically determine if the new position is acceptable in terms of function, phonetics, and esthetics. The provisional restorations can be adjusted until both the patient and the dentist are satisfied. This information is then transferred to the laboratory, and the definitive restorations are fabricated.

The authors utilized this approach to treatment plan complex patients and continue to use it today. However, with time, we realized that this approach also had shortcomings. The incisal edges of the maxillary anterior teeth could be in a perfect position, and yet the definitive restorative result could be a failure because the gingival tissues and/or smile frame were unesthetic (Fig 1-1).

Fig 1-1 Incisal edges in the correct positions but with unesthetic gingival levels. (a) Uneven gingival levels (note the right lateral incisor and canine). (b) Excessive gingival display. (c) Uneven gingival levels (note the central incisors) and excessive gingival display. (d) Uneven gingival levels (note the right lateral incisor and left canine).

Global Approach to Diagnosis and Treatment Planning

This was the genesis of the “global diagnosis” concept, a systematic approach to evaluate, diagnose, and treat aberrations in the gingival positions and the smile frame. In dentistry, there are four primary global diagnoses related to (1) the facial and skeletal proportions, (2) the length and mobility of the maxillary lip, (3) the relationship of the gingival line to horizon, and (4) the length of the clinical crowns of the relevant teeth. In order to determine the global diagnosis, the clinician must first collect a set of data that is not commonly gathered in a traditional dental examination. Chapter 2 defines each of the parameters required to make the global diagnosis along with their normative values. In addition, a form is provided to aid in the collection of the relevant data. In chapter 3, a set of five questions will allow the clinician to determine the global diagnosis. In chapters 4 through 9, the six tools available to treat the global diagnosis are discussed in detail. In chapter 10, special emphasis is given to the global diagnosis that most commonly impacts the treatment plan in the interdisciplinary patient: dentoalveolar extrusion. Once the global diagnosis has been established, it is time to sequence the treatment plan, which is the topic of chapter 11. Chapter 12 features a global diagnosis treatment-planning template that is used for organizing a diagnosis and treatment plan presentation for a patient or a study club. Finally, case studies using the global diagnosis system are presented in chapter 13.

References

1. Vig RG, Brundo GC. The kinetics of anterior tooth display. J Prosthet Dent 1978;39:502–504.

2. Gillen RJ, Schwartz, RS, Hilton TJ, Evans DB. An analysis of selected normative tooth proportions. Int J Prosthodont 1994;7:410–417.

2

Global Analysis Diagnosis Form

The Global Analysis Diagnosis form is the vehicle that leads the dentist through the Global Diagnosis system. This chapter provides instructions for completing the form as well as a set of normative numbers to be used in evaluating the interdisciplinary patient.

As with any dental examination, a reliable, expedient process of recording information is key. The “Global” Analysis Diagnosis (GAD) form (Fig 2-1) allows practitioners to record key esthetic and functional information in a small amount of time. With proper training, any staff member can accomplish the measurements. This allows it to be incorporated into almost any type of new patient experience, hygiene recall, or reevaluation. It generally requires no more than 5 minutes to complete the examination.

Fig 2-1 GAD form. CEJ, cementoenamel junction.

This chapter focuses on making proper measurements and demonstrates annotations used to record ideal and abnormal findings. The GAD form is organized from outside in, starting with the face and ending with the teeth, so as to reduce redundancy.

Face Height

Face height is a measurement used to evaluate facial proportions. The “rule of thirds” separates the ideal facial proportions into thirds in the horizontal plane1 (Fig 2-2). We are only concerned with the middle and lower thirds of the face. The middle third is measured from soft tissue glabella (the most prominent point between the eyebrows) to under the nose (subnasale) (Fig 2-3a). The lower third is measured from under the nose to under the chin (soft tissue menton) (Fig 2-3b). These measurements must be made in a repose position of the lips and jaw. Repose is defined as physiologic rest with lips and teeth slightly apart. The measurements are written on the GAD form as a ratio of the middle third to the lower third, and the first piece of the diagnostic puzzle is solved (Fig 2-4).

Fig 2-2 Rule of thirds. (A) Midface measurement is from soft tissue glabella, the most prominent point between the eyebrows, to under the nose. (B) The lower third is measured from the base of the nose to the base of the chin.

Fig 2-3(a) Middle third measurement from the soft tissue glabella to the base of the nose. (b) Lower third measurement from under the nose to under the chin. Note that the measurement is made with the lips and teeth apart in a repose position.

Fig 2-4 The face height measurements are recorded on the GAD form.

The face height measurement is critical to any esthetic evaluation because one of the four etiologies for a malpositioning of the teeth in the face is a skeletal discrepancy. The skeletal discrepancy that most commonly affects facial esthetics is vertical maxillary excess, an excessive downgrowth of the maxilla. If the lower third of the face is significantly longer than the middle third, an additional measurement may assist in determining if the problem is located in the maxilla or the mandible. The lower third proportion is ideally composed of one-third maxilla and two-thirds mandible. With the lips in repose, the maxilla measurement is from the base of the nose to the mid-commissure line, and the mandible measurement is from the mid-commissure line to the inferior border of the chin. However, the determination as to whether the problem is in the maxilla or mandible should be evaluated in the context of the patient’s emotional smile. If the smile does not appear to be gummy, the patient does not have a “problem.”

Lip Length

The upper and lower lips frame the smile. They are extremely important in displaying the beauty of the teeth. However, they are commonly ignored in the comprehensive dental examination. The upper lip length is measured from the base of the nose to the inferior border of the lip (Fig 2-5). The average length of an upper lip for a 30-year-old woman is between 20 and 22 mm. Upper lips of men are routinely 1 to 2 mm longer.2 Mandibular incisor display will increase throughout life as the lips lose tone. Lower lips that are asymmetric, cover the maxillary incisal edges, or display too much negative space will alter the framing of the smile (Fig 2-6). Tooth position as it relates to lip dynamics may need to be modified during the course of treatment.

Fig 2-5(a) Upper lip measurement from the base of the nose to the wet-dry border of the lip. (b) The upper lip must be measured in repose and at the midline.

Fig 2-6 The asymmetric lower lip in full smile impacts the esthetics.

Lip Mobility

The mobility of the upper lip is determined in one of two ways: direct measurement or mathematically. Measuring mobility begins with determining the amount of the central incisor displayed in repose. The patient relaxes the lip, and the distance from the incisal edge to the inferior border of the lip is determined (Fig 2-7a). The patient is then coached into a dynamic full smile. When the lip is at its highest position, the distance from incisal edge to the inferior border of the upper lip is measured (Fig 2-7b). Multiple locations of movement may be measured given that the lip may change in dynamics across the anterior teeth (Fig 2-8).

Fig 2-7(a) Lip mobility measurement begins from repose. (b) In full smile, measure from the same incisal edge position to the upper lip. The difference between the two measurements is the upper lip mobility. In this case, 9 mm in repose and 14 mm in full smile demonstrates a lip mobility of 5 mm.

Fig 2-8 The arch of the upper lip in an expressive smile routinely demonstrates additional gingival display over the lateral incisors and first premolars.

The mathematic method can be done directly from the GAD form. The amount of central incisor exposed in repose is subtracted from the total length of the central incisor. This equals the amount of tooth structure hidden by the lip in repose. If the lip moves to an ideal position at the free gingival margin (FGM) of the tooth, the amount of lip movement is equal to the amount hidden in repose. Finally, the number of millimeters of gingival display in full smile is added. The gingival display is the amount the upper lip moves past the FGM. Normal lip mobility is 6 to 8 mm.3

Interestingly, most patients have difficulty smiling on demand. They will either grimace or not smile to their normal full smile position. Because the position of their teeth in relation to their social smile is key to the authors’ global system, we utilize two different approaches to obtain a measurable smile. First, we ask the patient to laugh instead of smile. The command “smile” is many times met with a tooth-together grimace (Fig 2-9) rather than a relaxed smile with teeth apart. When patients are asked to laugh out loud, it demands that the teeth are not together and eliminates the grimace. With some effort, the patient can be coached into a smile that demonstrates a natural look. In patients who cannot be coached into a natural full smile, the “high E” rule is used. The patient is asked to say a long “E” out loud. The dentist then lightly touches the area beneath the patient’s eyes and asks the patient to flex these muscles and to move the upper lip as high as possible (Fig 2-10). If done correctly, the “high E” rule demonstrates the maximum mobility of the upper lip when evaluating the amount of gingival display.

Fig 2-9 A clenched-teeth grimace is typical of many patients asked to smile.

Fig 2-10(a) Smile lacks animation and does not demonstrate the full extent of upper lip activity. (b) “High E” smile demonstrates the maximum limits of the patient’s upper lip movement.

Dental-Facial Midline

The dental-facial midline measurement is used to determine the position of the maxillary dental midline in relation to the facial midline (Fig 2-11). Ideally, the maxillary dental midline should be perpendicular to the horizon (see Fig 2-11b) and coincident with the facial midline (Fig 2-12). The facial midline can be difficult to determine with the patient in a supine position. Many times the patient must be asked to stand in order for the dentist to evaluate. Three issues make the facial midline difficult to evaluate: (1) Most people have asymmetric faces, (2) the majority of noses deviate to one side, and (3) many people compensate for the asymmetry by canting their head (Fig 2-13). Two methods may assist with this measurement. First, the tip of the “Cupid’s bow” of the upper lip is generally coincident with the facial midline (Fig 2-14). Second, the patient can be asked to stand, and the head can be adjusted to be level with the horizon. It is then much easier to evaluate the midline relationships. The threshold for noticing facial tilt for both dentists and laypersons is less than 1%. The GAD charting will indicate whether the dental midline is in alignment with the facial midline or how many millimeters off it is and in which direction (eg, 2 mm right). Finally, the midline should be perpendicular to the horizon (see Fig 2-11b). If it is canted, this note is recorded as well as the direction of the cant. Alternatively, a line can be drawn on the teeth portion of the form indicating position and cant of the midline.

Fig 2-11(a and b) The maxillary central incisor midline is viewed as it relates to the facial midline.

Fig 2-12(a) Facial and dental midlines not coincident in repose. (b) Facial and dental midlines not coincident in full smile.

Fig 2-13(a) Patients routinely alter their head position to correct for a dental asymmetry. (b) When the patient’s head is straightened, the dental midline cant becomes apparent.

Fig 2-14 Contours of the face can make evaluation of the midlines difficult. The tip of the Cupid’s bow of the upper lip usually represents the midline of the face.

A number of studies have investigated the esthetic importance of the dental-facial midline.4,5 The results indicate that perfect midline harmony is of little importance. The majority of studies have found that if the maxillary dental midline is within 2 mm of the facial midline, it is deemed acceptable. However, one important study went so far as to suggest that 4 mm may be acceptable to general dentists and the lay public and 3 mm to orthodontists.6 Methodologic problems prevent acceptance of those results given the preponderance of evidence to suggest otherwise (Fig 2-15). The authors believe that a discrepancy of less than 2 mm is acceptable. If the observer is given a reference of the lips and face, a 3- to 4-mm deviation creates a visual tension that is unacceptable.

Fig 2-15