Lingual orthodontics explained

The Occlusal Plane in Orthodontics: A Comprehensive Analysis of its Diagnostic, Functional, and Therapeutic Significance

Introduction: The Centrality of the Occlusal Plane

The occlusal plane (OP) represents a foundational, yet profoundly complex, reference structure within the fields of orthodontics and craniofacial biology. It is far more than a simple line on a cephalogram; it is the critical interface linking the maxillary and mandibular dentitions, the craniofacial skeleton, the functional matrix of the masticatory system, and the aesthetic framework of the lower face.1 Historically, the orientation of the occlusal plane has been the subject of considerable controversy and evolving understanding, reflecting its pivotal role in function, aesthetics, and speech.4 A nuanced comprehension of the OP's inclination is therefore indispensable for accurate diagnosis, effective treatment planning, and the achievement of stable, functional, and aesthetically pleasing outcomes. This report provides a comprehensive analysis of the occlusal plane, examining its anatomical definition, its role as a diagnostic indicator of craniofacial form, its profound clinical significance, the methods for its therapeutic alteration, and its conceptualization within major orthodontic philosophies.

Section 1: Anatomical Definition and Cephalometric Analysis

To appreciate the clinical relevance of the occlusal plane, one must first deconstruct its definition, recognizing it as a clinical and radiographic abstraction of a complex, three-dimensional anatomical reality. The methodologies used for its measurement are critical, as the choice of definition and reference structure directly influences diagnostic interpretation.

1.1 Deconstructing the Occlusal Plane: From Idealization to Clinical Reality

The occlusal plane is fundamentally defined as an imaginary surface established by the incisal and occlusal surfaces of the teeth.6 It is not a true geometric plane but rather a representation of the average curvature of these surfaces, playing a critical role in the proper distribution of forces during mastication.6 This three-dimensional curvature is a composite of two distinct curves:

• The Curve of Spee: Viewed in the sagittal plane, this is the anteroposterior curve extending from the tip of the mandibular canine, following the buccal cusp tips of the premolars and molars.8
• The Curve of Wilson: Viewed in the frontal plane, this is the mediolateral curve formed by the buccal and lingual cusp tips of the posterior teeth. It is typically concave in the mandibular arch and convex in the maxillary arch.8

These curves are functionally significant, allowing for the disclusion of posterior teeth during protrusive and lateral movements of the mandible, a concept central to the philosophy of mutually protected occlusion.8 For two-dimensional cephalometric analysis, this curved reality must be simplified into a straight line. However, there is no universal consensus on how this line should be drawn, leading to several distinct definitions with different clinical implications 2:

• Bisected Occlusal Plane (BOP): First described by Downs, the BOP is a line connecting a point that bisects the cusp height of the first molars with a point that bisects the incisal overbite.9 It provides a general representation of the entire dental arch.
• Functional Occlusal Plane (FOP): Also referred to as the Posterior Occlusal Plane (POP), the FOP is defined by the intercuspation of the premolars and first molars.2 Proponents, notably Dr. Sadao Sato, consider this plane to be more intimately related to mandibular function and position, as it represents the primary area of mastication.2
• Other Definitions: Various other definitions exist, such as the Upper Occlusal Plane (connecting maxillary incisor edges to maxillary first molar cusps) and the Lower Occlusal Plane, further illustrating the variability in its clinical application.2

The variance between these definitions is not merely academic. The FOP has been shown to be more sensitive to underlying skeletal discrepancies, while the BOP is more reflective of dentoalveolar compensations.2 This can create a diagnostic paradox. For instance, in a skeletal Class II patient, the incisors may have flared forward and extruded as a natural compensation to reduce the overjet. When drawing the BOP, this anterior dental compensation can artificially flatten the plane, potentially masking the severity of the underlying skeletal jaw discrepancy when measured with an indicator like the Wits appraisal. The FOP, by ignoring the compensated anterior teeth, provides a more accurate representation of the posterior dental unit's relationship to the jaws. Therefore, a significant divergence between the BOP and FOP is itself a powerful diagnostic sign, indicating that substantial dental compensation has occurred to camouflage a skeletal problem.2

1.2 Cranial Reference Planes for Measurement

To quantify the inclination of the variable occlusal plane, it must be measured against stable, reproducible cranial reference planes. The most commonly used planes in cephalometrics include:

• The Frankfort Horizontal (FH) Plane: Drawn from Porion (the superior point of the external auditory meatus) to Orbitale (the lowest point on the infraorbital margin), the FH plane is intended to represent the natural horizontal orientation of the head in space.4
• The Sella-Nasion (S-N) Plane: Connecting the center of the sella turcica (S) to Nasion (N), this plane represents the anterior cranial base and is a cornerstone of many cephalometric analyses, including Steiner's.10
• The Palatal Plane (PP): Extending from the Anterior Nasal Spine (ANS) to the Posterior Nasal Spine (PNS), it defines the orientation of the maxilla relative to the cranium.4
• The Mandibular Plane (MP): Typically drawn as a tangent to the lower border of the mandible from Gonion (Go) to Menton (Me) or Gnathion (Gn), it represents the orientation of the mandible.4
• Camper's Plane: A clinical soft-tissue reference from the ala of the nose to the tragus of the ear, often used in prosthodontics as an external guide for establishing the occlusal plane.4

The historical context of these reference planes reveals a critical issue in modern digital orthodontics. For many years, physical diagnostic study models were meticulously trimmed so that their bases were parallel to the Frankfort Horizontal plane.16 This practice provided clinicians with a true, tangible representation of the patient's actual occlusal plane angle and its relationship to the cranium, intuitively informing decisions about incisor torque and smile arc aesthetics.16 The contemporary standard, adopted for the pragmatic reason of preventing model breakage, is to trim the models with the occlusal plane parallel to the floor.16 This procedural shift, while seemingly minor, has had a profound and detrimental downstream effect. Most modern virtual treatment planning platforms (e.g., Invisalign ClinCheck, OrthoCAD) have inherited this "flat" orientation as a default, divorcing the digital model from its true craniofacial context.16 This creates a fundamental flaw: an orthodontist planning treatment on a virtually flattened model is prescribing tooth movements relative to an artificial horizontal plane. The prescribed incisor torque might be numerically correct within the software but clinically incorrect for the patient. For an individual with a steep 16° occlusal plane, the "ideal" torque prescribed on a flat virtual model will result in excessively uprighted incisors in reality, leading to aesthetic compromises like a flattened smile arc and potential treatment relapse.10 This highlights a critical need to integrate cephalometric or 3D facial data to correctly orient virtual models as a standard of care.

1.3 Key Angular Measurements and Their Interpretation

The relationship between the occlusal plane and the cranial reference planes is quantified through several key angular measurements:

• OP-FH Angle (Cant of the Occlusal Plane): Measures the slope of the OP relative to the Frankfort Horizontal. In the Downs analysis, the mean value is approximately 9.3°.5 A normal value is often cited as $8° \pm 4°$.17
• OP-SN Angle: Measures the slope of the OP relative to the S-N line. According to Steiner, the mean value for this angle is 14°.10
• Occluso-Mandibular (OM) Angle: The angle between the OP and the Mandibular Plane. Unlike the OP-FH or OP-SN angles, which are relatively constant across different facial types, the OM angle is highly variable.5 It is a sensitive indicator of the vertical relationship between the posterior dentition and the mandible, reflecting the relative vertical heights of the anterior and posterior dental segments.5
• OP-Palatal Plane Angle: This angle indicates the relationship between the maxillary dentition and its own skeletal base, the maxilla. The mean value is approximately 6-7°.4

Section 2: The Occlusal Plane as a Diagnostic Indicator of Craniofacial Form

The inclination of the occlusal plane is not an isolated variable. It is a dependent characteristic that reflects and is intrinsically linked to an individual's innate skeletal and soft tissue morphology. Its angle serves as a powerful diagnostic indicator of underlying vertical and sagittal growth patterns.

2.1 Relationship with Vertical Skeletal Patterns (The Vertical Dimension)

There is a strong and consistent correlation between the inclination of the occlusal plane and the vertical dimension of the face.1 This relationship is a cornerstone of cephalometric diagnosis.

• Hyperdivergent Pattern (Dolichofacial/Long-Face): Characterized by a downward and backward rotation of the mandible and a high Frankfort-Mandibular Plane Angle (FMA > 28°), this pattern is strongly associated with a steeper-than-normal occlusal plane.1
• Hypodivergent Pattern (Brachyfacial/Short-Face): Characterized by a forward and upward (counter-clockwise) rotation of the mandible and a low FMA (< 21°), this pattern is consistently associated with a flatter-than-normal occlusal plane.1
• Normodivergent Pattern (Mesofacial): Representing a balanced vertical growth pattern, these individuals typically exhibit an occlusal plane inclination within the normal range.18

2.2 Relationship with Sagittal Skeletal Patterns (Malocclusion Class)

The OP inclination also correlates with anteroposterior skeletal discrepancies, often acting as a form of natural dentoalveolar compensation.2

• Skeletal Class II: Patients with a Class II skeletal pattern, particularly those with mandibular retrusion and a hyperdivergent tendency, exhibit a statistically significant trend towards a steeper occlusal plane.1
• Skeletal Class III: Conversely, patients with a Class III skeletal pattern, especially those with mandibular prognathism and a hypodivergent tendency, often present with a flatter occlusal plane.1

While the conventional view holds that the underlying skeletal growth pattern causes the corresponding occlusal plane inclination, a more dynamic interpretation, championed by researchers like Dr. Sadao Sato, posits a functional feedback loop.2 This perspective suggests the OP is not merely a passive result but an active participant in the development of the craniofacial form. For example, a premature posterior occlusal contact during growth may cause the mandible to functionally rotate downward and backward to achieve a more comfortable intercuspation.12 When this adaptive posture is repeated over thousands of masticatory cycles, it can guide and exacerbate a hyperdivergent skeletal growth pattern, with the steepening OP acting as a "ramp" that directs mandibular growth posteriorly.9 This reframes the OP from a simple diagnostic marker to a potential etiological factor and, consequently, a primary therapeutic target.

Table 1: Cephalometric Norms and Observed Tendencies of Occlusal Plane Inclination

The following table synthesizes normative data and observed clinical tendencies to provide a diagnostic reference for evaluating a patient's occlusal plane inclination in the context of their craniofacial pattern. Numerical values represent mean ± standard deviation where available; descriptive terms are used where a strong correlation is established in the literature.

Cephalometric Measurement Normodivergent / Class I Hyperdivergent / Class II Tendency Hypodivergent / Class III Tendency Data Sources OP-FH Angle $8.6^\circ – 9.3^\circ$ Steeper (> $12^\circ$) Flatter (< $4^\circ$) 4 OP-SN Angle $14^\circ \pm \sim4^\circ$ Steeper Flatter 10 OP-Mandibular Plane Angle $12.6^\circ – 16.8^\circ$ Increased (> $20^\circ$) Decreased (< $11^\circ$) 4 Frankfort-Mandibular Plane Angle (FMA) $21^\circ – 28^\circ$ High (> $28^\circ$) Low (< $21^\circ$) 10 ANB Angle $2^\circ \pm 2^\circ$ Increased (> $4^\circ$) Decreased (< $0^\circ$) 10 Qualitative OP Description Normal Steep Flat 1

Section 3: The Clinical Significance of Occlusal Plane Inclination

The measurement and diagnosis of the occlusal plane's inclination are critical because of its profound impact on the function of the masticatory system, the health of the temporomandibular joints, and the aesthetics of the smile and lower face.

3.1 Functional Biomechanics and Temporomandibular Health

The occlusal plane is a key determinant of functional harmony within the stomatognathic system.9

• Guidance and Force Distribution: The OP works in concert with posterior condylar guidance and anterior incisal guidance to direct mandibular movements. The Curves of Spee and Wilson are essential for achieving posterior disclusion during excursions, which protects the posterior teeth from damaging non-axial forces.8 A well-organized OP also facilitates simultaneous, bilateral posterior contacts in the maximal intercuspal position, which is fundamental for the even distribution and dissipation of occlusal forces through the teeth, periodontium, and alveolar bone.8
• Temporomandibular Joint (TMJ) Loading: The inclination of the OP directly influences the biomechanics and stress distribution within the TMJ.24 Finite element analysis has demonstrated that altering the OP changes the direction of occlusal forces transmitted to the joint structures. Specifically, a clockwise rotation (steepening) of the OP leads to an increase in compressive stress on the mandibular condyle. Both clockwise and counter-clockwise rotations cause a shift in the stress patterns on the articular disc.25 This provides a clear biomechanical link between iatrogenic or pathological changes in OP inclination and the potential for developing temporomandibular disorders (TMDs).

3.2 The Aesthetics of the Smile and Face

The orientation of the occlusal plane is a pivotal factor in defining the aesthetics of the lower third of the face and, most importantly, the smile.3

• The Smile Arc: The smile arc is the relationship between the curvature of the maxillary incisal edges and the curvature of the lower lip during a social smile.27 An aesthetically ideal, or "consonant," smile arc is one where the maxillary incisal curve is parallel to the curve of the lower lip.9 The OP inclination directly governs this relationship. A steep OP can result in an overly accentuated or "gummy" smile arc, whereas a flat OP can lead to a non-consonant, flattened, or even reversed smile arc, which is perceived as less attractive.16
• Incisor and Gingival Display: The vertical position of the anterior portion of the OP determines the amount of tooth and gum tissue visible. An acceptable aesthetic standard is generally considered to be 2-4 mm of maxillary incisor display when the lips are at rest, and 0-2 mm of gingival display during a full smile.23 A steep OP is often associated with excessive gingival display.29
• Occlusal Plane Cant: In the frontal dimension, a mediolateral tilt of the occlusal plane is known as a "cant." An occlusal cant is a significant aesthetic deformity that disrupts facial symmetry and is frequently associated with mandibular deviation.23 The threshold for perception of an occlusal cant varies. Orthodontists are highly sensitive, able to detect cants as small as 4°, while laypeople and general dentists typically perceive them when they approach 6°.31 For individuals with mesofacial or dolichofacial patterns, even a 2° cant is rated as significantly less aesthetic than a level 0° plane by orthodontic specialists.32

The management of the smile arc reveals an inherent tension between aesthetic ideals and functional realities. A popular clinical strategy to enhance the smile arc involves placing maxillary anterior brackets more gingivally to extrude the incisors and accentuate their curvature.27 However, this approach cannot be applied universally. The patient's native occlusal plane inclination provides the fundamental context for any such aesthetic manipulation. For a patient who already possesses a steep OP (e.g., 10° or greater), further incisor extrusion will likely create an unattractive, excessively curved smile arc. In contrast, for a patient with a flat OP (e.g., 5°), a modest amount of incisor extrusion can be aesthetically beneficial.27 Therefore, the ideal smile arc is not an absolute but is relative to the patient's underlying craniofacial structure. Treatment planning must first assess the skeletal OP angle and then determine the appropriate incisor position to create a consonant smile arc within that specific anatomical framework.

Section 4: Therapeutic Alteration of the Occlusal Plane

Given its diagnostic and clinical importance, the ability to purposefully alter the occlusal plane is a cornerstone of advanced orthodontic and surgical treatment. The methods range from subtle dental movements to profound skeletal repositioning.

4.1 Non-Surgical Orthodontic Modification

Orthodontic mechanics can influence the OP, though often with limitations and potential side effects.

• Extraction vs. Non-Extraction Mechanics: In the camouflage treatment of skeletal Class II malocclusions, the choice of extraction can significantly impact the OP. Treatment involving the extraction of maxillary premolars, a common approach to reduce overjet, has been shown to cause an increase, or steepening, of the occlusal plane inclination.11 This iatrogenic steepening is a critical side effect to anticipate and manage, as it is often associated with treatment relapse.10
• Vertical Control with Molar Intrusion: The most effective non-surgical method for controlling and correcting a steep occlusal plane is the intrusion of posterior teeth. While historically attempted with high-pull headgear, the contemporary standard for achieving true molar intrusion is the use of Temporary Anchorage Devices (TADs), or mini-screws.34 By providing absolute skeletal anchorage, TADs allow for the intrusion of maxillary molars, which in turn facilitates a counter-clockwise (flattening) rotation of the occlusal plane and subsequent autorotation of the mandible. In some high-angle cases, this can be a powerful enough tool to achieve a surgical-like result and avoid the need for a LeFort I osteotomy.12
• Multiloop Edgewise Archwire (MEAW) Therapy: This specialized wire-bending technique is designed specifically for the treatment of severe malocclusions like open bites. By incorporating multiple loops, the archwire provides low, continuous forces that allow for differential vertical control of dental segments. MEAW therapy can effectively level disparate occlusal planes (e.g., a steep posterior plane and a flat anterior plane), resulting in a flattening of the overall OP and closure of the bite, with studies demonstrating good long-term stability.35

4.2 Growth Modification with Functional Appliances

In growing patients with Class II malocclusions, functional appliances are used to modify growth patterns and correct the jaw discrepancy.

• Twin Block Appliance: This removable appliance consists of interlocking acrylic bite blocks with inclined planes that posture the mandible forward.36 Its primary effects are dentoalveolar, including proclination of the lower incisors and retroclination of the uppers.38 While it can increase lower anterior facial height via extrusion of the lower molars, its effect on the overall occlusal plane inclination is variable and is not its primary mechanism of correction.37
• Herbst Appliance: This is a fixed, tube-and-rod telescopic appliance that continuously holds the mandible in a protruded position.40 Studies have shown that the Herbst appliance can cause a clockwise rotation (steepening) of the occlusal plane, which contributes to the correction of the Class II molar relationship and overjet.40 This effect is often accompanied by a significant and sometimes undesirable proclination of the mandibular incisors.42

4.3 Orthognathic Surgical Correction

For adult patients with significant skeletal discrepancies, orthognathic surgery is the most definitive method for altering the occlusal plane.

• The LeFort I Osteotomy: This versatile procedure involves surgically separating the maxilla from the rest of the midface, allowing it to be repositioned in all three dimensions.44 This provides direct and predictable control over the occlusal plane's final position.
• Counter-Clockwise (CCW) Rotation: This maneuver, which flattens the occlusal plane, is a cornerstone of treating hyperdivergent (long-face) patients. It is typically achieved through posterior maxillary impaction, which allows the mandible to autorotate upward and forward. This single movement simultaneously reduces the anterior facial height, improves chin projection, and flattens the steep OP.17 Each millimeter of posterior maxillary impaction results in approximately $2.25^\circ$ of OP flattening.46
• Clockwise (CW) Rotation: This maneuver, which steepens the occlusal plane, is used to treat hypodivergent (short-face) patients, often with a Class III malocclusion. It is achieved by impacting the anterior maxilla or down-grafting the posterior maxilla, which increases the anterior facial height and rotates the mandible downward and backward.17
• Stability of Surgical Changes: The long-term stability of surgical OP rotation is a critical consideration. There is a notable contradiction within the literature on this topic. One body of research suggests that surgically induced clockwise rotation is highly stable, while counter-clockwise rotation is less stable and demonstrates a significant tendency to relapse toward its original steep inclination.49 However, other studies assert that CCW rotations are stable when executed with proper treatment planning, precise surgical technique, and in the presence of healthy TMJs.45 This discrepancy suggests that the stability of CCW rotation is not absolute but is likely multifactorial and conditional. It may depend on the degree of rotation, the rigidity of surgical fixation, the management of the condyle during surgery, and the precision of the postoperative orthodontic finishing. The successful and stable flattening of the occlusal plane in high-angle patients likely requires not just skeletal movement but a complete adaptation of the neuromuscular system to the new, less-strained vertical dimension.

Section 5: Foundational Philosophies in Occlusal Plane Management

The clinical management of the occlusal plane is not monolithic; it is deeply influenced by the core principles of different orthodontic philosophies. How an orthodontist views and treats the OP is often a direct reflection of their fundamental treatment priorities, whether they be dental stability, facial growth, or gnathological function.

5.1 The Tweed-Merrifield Philosophy: Vertical Control and Incisor Stability

The Tweed-Merrifield philosophy is predicated on achieving facial harmony and long-term stability by positioning the mandibular incisors upright over basal bone, a goal that frequently necessitates the extraction of teeth.50 Within this framework, the occlusal plane is a key variable that must be rigorously controlled. The "Differential Diagnostic Analysis System" identifies control of the vertical dimension—assessed via the FMA and the occlusal plane angle—as essential for successful treatment.52 A specific treatment goal is to achieve an occlusal plane angle of 7° or less relative to the mandibular plane.52 The philosophy emphasizes the use of meticulous directional force mechanics to prevent unwanted molar extrusion and the consequent steepening of the occlusal plane, which is viewed as a primary cause of instability and poor aesthetics.54

5.2 The Ricketts Bioprogressive Philosophy: The Total Face and Growth Forecasting

The Bioprogressive philosophy, developed by Dr. Robert Ricketts, expanded the focus of orthodontics from the teeth and occlusion to the "total face".56 A central tool of this philosophy is the Visualized Treatment Objective (VTO), a method of forecasting craniofacial growth and the effects of treatment.58 Ricketts placed significant emphasis on the OP's relationship to the geometric center of the mandibular ramus, a point he designated "Xi." He theorized that a steep occlusal plane, positioned above Xi point, acted as a functional impediment to the forward growth of the mandible.59 Consequently, a key therapeutic goal in Bioprogressive therapy is to level a steep OP, often through molar intrusion with appliances like the utility arch, to position it at or below Xi point. This was believed to "unlock" the mandible, allowing for a more favorable forward expression of growth.59 Ricketts also recognized the complexity of the OP, differentiating a "True Buccal Occlusal Plane" for more precise diagnosis in cases with anterior dental aberrations.58

5.3 The Roth Gnathological Philosophy: Condylar Position and Functional Harmony

The philosophy of Dr. Ronald Roth is rooted in the principles of gnathology, which prioritize the health and function of the entire masticatory system, including the TMJs.61 The primary goal of Roth's approach is to achieve a mutually protected occlusion where the teeth function in harmony with the mandibular condyles seated in their most stable, musculoskeletally-derived position, known as Centric Relation.61 In this philosophy, the final inclination of the occlusal plane is not a primary therapeutic target in itself, but rather the result of achieving the primary gnathological goals.63 The teeth are positioned to provide proper anterior guidance and posterior disclusion relative to the seated condylar position. The occlusal plane that results from this functional arrangement is, by definition, the correct and most stable one for that individual patient. The OP is therefore subservient to the health of the TMJs and the overall functional harmony of the system. These differing philosophies can be viewed along a "cause and effect" spectrum. For Tweed, the OP is a variable to be actively controlled to achieve a desired dental position (the effect). For Ricketts, the OP is a key factor to be manipulated to influence a desired growth response (the cause of a new effect). For Roth, the OP is the passive outcome of establishing a healthy gnathological foundation (accepting the effect of a proper cause). This synthesis reveals that the "ideal" occlusal plane is not a universal constant but is philosophy-dependent, reflecting a clinician's fundamental treatment priorities.

Conclusion: Integrating the Occlusal Plane into Modern Clinical Practice

The inclination of the occlusal plane is a dynamic, multi-faceted entity that stands as a crucial parameter in orthodontic diagnosis and treatment. A comprehensive evaluation must consider it from skeletal, functional, and aesthetic perspectives. Its angle is a powerful indicator of a patient's underlying craniofacial growth pattern, a key determinant of masticatory function and TMJ health, and a fundamental component of smile aesthetics.1 The evidence strongly suggests that the final position of the occlusal plane should not be dictated by a single normative value but must be customized to the individual patient. The treatment plan must be tailored to the patient's unique craniofacial morphology, functional requirements, and aesthetic goals, with a clear understanding of the stability and relapse potential associated with the planned changes.2 Furthermore, in the modern era of digital orthodontics, the critical importance of correct three-dimensional orientation in virtual treatment planning cannot be overstated. The common practice of analyzing and planning treatment on virtually flattened models introduces a fundamental diagnostic and therapeutic error that can compromise clinical outcomes.16 The integration of cephalometric or CBCT data to establish the true craniofacial orientation of digital models should be considered a standard of care. Ultimately, a holistic understanding and meticulous management of the occlusal plane are paramount for achieving more effective, efficient, and stable results in orthodontic therapy. Nguồn trích dẫn 1. The occlusal plane inclination relative to craniofacial form: A cephalometric investigation – The Research Repository @ WVU – West Virginia University, truy cập vào tháng 10 19, 2025, https://researchrepository.wvu.edu/etd/572/ 2. Variance in occlusal plane identification in different literature – AnalyzeCeph, truy cập vào tháng 10 19, 2025, https://www.analyzeceph.com/variance-in-occlusal-plane-identification-in-different-literature/ 3. Factors associated with occlusal plane inclination – European Journal of Oral and Maxillofacial Surgery 2024 December;8(3):47-51, truy cập vào tháng 10 19, 2025, https://www.minervamedica.it/en/journals/maxillofacial-surgery/article.php?cod=R53Y2024N03A0047 4. Reliability of Anatomic Reference Planes in Establishing the …, truy cập vào tháng 10 19, 2025, https://pmc.ncbi.nlm.nih.gov/articles/PMC3792304/ 5. Cant Of The Occlusal – Inclinations Of Teeth – Allen Press, truy cập vào tháng 10 19, 2025, https://meridian.allenpress.com/angle-orthodontist/article-pdf/33/2/69/1367600/0003-3219(1963)033_0069_cotopa_2_0_co_2.pdf 6. pocketdentistry.com, truy cập vào tháng 10 19, 2025, https://pocketdentistry.com/occlusal-plane/#:~:text=The%20occlusal%20plane%20is%20defined,%5BFigure%2012%2D01%5D. 7. Occlusal Plane: Definition & Importance – StudySmarter, truy cập vào tháng 10 19, 2025, https://www.studysmarter.co.uk/explanations/medicine/dentistry/occlusal-plane/ 8. Occlusal plane | Pocket Dentistry, truy cập vào tháng 10 19, 2025, https://pocketdentistry.com/occlusal-plane/ 9. Changes of occlusal plane inclination after orthodontic treatment in different dentoskeletal frames – PMC – PubMed Central, truy cập vào tháng 10 19, 2025, https://pmc.ncbi.nlm.nih.gov/articles/PMC4884032/ 10. © 2022 Kois Center, LLC, truy cập vào tháng 10 19, 2025, https://www.koiscenter.com/wp-content/uploads/2022/08/Cephalometric-Data.pdf 11. Changes of occlusal plane inclination after orthodontic treatment with and without extraction in Class II patients – Caspian Journal of Dental Research, truy cập vào tháng 10 19, 2025, https://cjdr.ir/article-1-279-en.pdf 12. Occlusal Plane, Mandibular Position and Dentoalveolar Changes during the Orthodontic Treatment with the Use of Mini-Screws – MDPI, truy cập vào tháng 10 19, 2025, https://www.mdpi.com/2304-6767/12/9/278 13. CEPHALOMETRICS – 2 – Terna Dental College, truy cập vào tháng 10 19, 2025, https://ternadental.com/wp-content/uploads/14.Cephalometrics-2.pdf 14. Cephalometric evaluation of incisor position – University of Michigan, truy cập vào tháng 10 19, 2025, https://media.dent.umich.edu/labs/mcnamara/files/Cephalometric%20evaluation%20of%20incisor%20position.pdf 15. A Cephalometric Analysis Assessing the Validity of Camper's Plane to Establishing the Occlusal Plane in Edentulous Patients – MDPI, truy cập vào tháng 10 19, 2025, https://www.mdpi.com/2304-6767/11/3/81 16. Pitfalls in 2011 Virtual Models: Occlusal Plane Limitations, truy cập vào tháng 10 19, 2025, https://www.jco-online.com/archive/2011/04/217-importance-of-the-occlusal-plane-in-virtual-treatment-planning/ 17. Changes in occlusal plane through orthognathic … – SciELO Brasil, truy cập vào tháng 10 19, 2025, https://www.scielo.br/j/dpjo/a/DYPbmGTf4vwCsZVMSfr4fBN/ 18. 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