• After treatments with implant-supported prostheses: The distribution of occlusal forces between teeth or implants, or even in implant-supported and implant-retained prostheses, reduces the rate of complications such as loosening of the prosthetic screws, fracture of the restorative material, or fracture of the implant.

Contraindications of occlusal adjustments

• Disorders of the temporomandibular joints (TMJs): The TMJs should present satisfactory function and be asymptomatic before any irreversible change is performed at the occlusal level. Despite the redistribution of functional forces, occlusal adjustment cannot predictably guarantee symptom relief. Ideally, the health status of the TMJs and masticatory muscles should be restored in the preliminary stages of treatment, conservatively and reversibly, with stabilizing interocclusal splints, together (or not) with physical therapy or medication.
• Muscular dysfunction: Occlusal adjustment should not be indicated in patients with hyperactive masticatory muscles because they do not allow coordinated mandibular movement patterns. Devices aimed at neuromuscular “deprogramming,” such as a jig², leaf gauge³, fronto-plateau⁴, or Kois therapeutic deprogrammer^5,6, can be used for varying periods to decrease the degree of muscle hyperactivity and improve muscle coordination (more details in Chapter 9).
• Search for an “ideal” occlusal model: It is not recommended to perform occlusal adjustment in search of an “ideal” morphologic pattern in patients who do not show signs or symptoms of a stomatognathic system in a pathologic state (more details in Chapter 7). Thus, the indication of an occlusal adjustment is directly related to the individual functional diagnosis, and adjustments are not recommended unless there are clear signs of deterioration and instability of the system. All therapeutic efforts should be carefully analyzed within a cost–benefit ratio, with the dentist proposing the most straightforward and least invasive therapy possible to eliminate or control the identified causal agents.

If the maximal intercuspal position (MIP) and centric relation (CR) are different without causing any symptoms, no adjustment is required^7–9. Ramfjord and Ash⁴ clarified that the term “occlusal interference” refers to an occlusal contact that significantly disturbs the functional or parafunctional movements of the mandible, and that not all contacts on the non-working side are necessarily problematic or undesirable. Such contacts are widespread in the natural dentition, present in 34% to 89% of individuals^10–16. Therefore, following the same reasoning as for the adjustment of the centric contacts, the adjustment of the tooth contacts on the non-working side is not indicated when the patient’s stomatognathic system is in a physiologic state.

• General health problems: Any non-essential dental treatment should be postponed until the patient is healthy enough for it to be performed effectively.
• Occlusal dysesthesia: This is a psychosomatic disorder characterized by a persistent sensation of occlusal discomfort without an apparent or identifiable cause. Patients who have this disorder often have an extensive history of frustrations and concerns related to previously performed occlusal adjustments. Many of them present subjective reports that are difficult to correlate with the actual current clinical findings, claiming that they never “felt” that the previous adjustments were correct or sufficient, even after several clinical appointments^17–21.
• Lack of patient interest or collaboration: Occlusal adjustment should only be performed in patients who are aware of the importance of the procedure for treatment stability and a good prognosis.

Diagnosis

The need for and extent of occlusal adjustment are directly linked to the anamnesis and functional clinical examination, which will determine the diagnosis of a stomatognathic system in either a physiologic or pathologic state. As previously discussed, when the stomatognathic system is in a physiologic state there is a balance, without relevant signs and symptoms and with no indication to change the MIP. Although the patient has a satisfactory adaptive response, it is possible that specific situations of teeth with signs of overload presenting tooth sensitivity or hypermobility may occur, which could require a careful adjustment to distribute the forces more appropriately.

The occlusal adjustment on restorations of one or a few teeth performed in a stomatognathic system in a physiologic state should respect the current occlusal references and fit harmoniously within the existing envelope of function. Premature contacts or interference cannot be introduced in CR, MIP, or lateral and protrusive movements, as they may demand different adaptive responses and influence treatment stability^22,23. This situation is common, being part of most restorative work in daily practice.

The occlusal scheme should be reorganized if extensive restorative treatment is indicated for esthetic, functional, structural, or biologic reasons. The CR, or, depending on the functional diagnosis, the adapted centric position (ACP), will be the maxillomandibular relationship of choice in these situations because it is a reproducible position and is independent of the tooth contacts that will be changed. Therefore, both the existing teeth and restorations as well as any temporary restorations must be meticulously fitted in CR²⁴.

Therapeutic objectives of occlusal adjustment

Occlusal adjustment is performed primarily to obtain the masticatory efficiency, occlusal stability, comfort, and health of the stomatognathic system. The scientific literature^24–29, combined with clinical experience, have made evident the following biomechanical parameters to be instituted at the end of the procedure [Figure 13-01A–H]:

[Figure 13-01A–H] Therapeutic objectives of occlusal adjustment: Occlusal contacts should occur simultaneously in CR and MIP [A]. The resultant forces of the occlusal contacts need to be arranged along the long axis of the tooth [B]. The functional guidance on the canine should provide disclusion of the posterior teeth, on the working and non-working sides, during mandibular lateral movements [C]. Contacts on the working side are permitted with an occlusal scheme in group function, correctly adjusted [D]. The incisal guidance should disclude all posterior teeth during protrusive and incisal mandibular movements. It is usually executed symmetrically by the central incisors, sometimes accompanied by the lateral incisors and less frequently by the canines [E]. Assess the need to provide an anterior area of freedom in centric to accommodate variations in head posture according to the patient’s envelope of function [F]. The occlusal plane should be correctly aligned and leveled [G]. The patient’s VDO should be functionally and esthetically acceptable [H].

1. Occlusal contacts should occur bilaterally and simultaneously in CR and MIP. The intensity of the contacts between the anterior teeth should be of lesser magnitude in the posterior teeth.
2. The resultant forces of the occlusal contacts need to be arranged along the long axis of the tooth.
3. The functional guidance on the canine should provide disclusion of the posterior teeth, on the working and non-working sides, during mandibular lateral movements. Contacts on the working side are permitted with an occlusal scheme in group function.
4. The incisal guidance should disclude all posterior teeth during mandibular protrusive and incisal movements. It is usually exerted symmetrically by the central incisors, sometimes by the lateral incisors, and less frequently by the canines.
5. An anterior area of freedom in centric should be provided, whenever necessary, to accommodate head posture variations according to the patient’s envelope of function.
6. The occlusal plane should be correctly aligned and level.
7. The patient’s vertical dimension of occlusion (VDO) should be functionally and esthetically acceptable.

Articulating TAPES for marking occlusal contacts

Articulating tapes are indispensable for analyzing and adjusting tooth contacts during mastication, swallowing, and parafunction.

The sensitivity and reliability of articulating tapes for marking contacts depend on their material and thickness. Their effectiveness will still be influenced by the conditions of use and the dentist’s subjective interpretation of the morphology of the markings obtained^30–33.

The thicker the articulating tape, the greater the number and extent of marked contacts. Thinner articulating tapes, from 8 to 40 micrometers (μm), are recommended by most authors for finalizing the adjustments, as they provide clear markings and do not interfere with the patient’s proprioceptive system. Thicker tapes can also cause mandibular deflections during adjustments^33,35,36.

It is necessary to clarify that the extent of the markings produced by the articulating tape does not correspond precisely to the intensity of the occlusal contacts. Kerstein³⁶ reported reliability of only 21% between the size of the marks and the forces applied to the teeth. That author also stated that different markings can represent the same force intensity, and that markings of the same sizes can indicate different forces. The extent of the markings is also related to the occlusal surface anatomy, with a broad and flat cusp tending to generate a wide mark^35,37.

The use of articulating tape unilaterally should be reserved for adjusting a few teeth, according to a conformative approach. The presence of the tape in only one hemiarch of the patient can cause minor mandibular deviations triggered by the proprioceptive system or by a difference in muscle tension on that side, with a tendency to make the contacts stronger on the analyzed side³⁸.

As this is a procedure performed very frequently in the dental clinic, it is recommended that the dentist has different articulating tapes, as they have different characteristics for use in very diverse situations. The articulating tape can be made of paper, polyester, or silk. It is suggested that the tapes be stored in a cool or refrigerated environment so that their components do not deteriorate.

Paper articulating tape: These have thicknesses from 40 μm³⁹. They are not very flexible and can generate false positives because they do not adapt to the anatomy of the antagonistic surfaces and are quickly degraded in the presence of excess saliva. Due to their texture, they create greater friction during occlusal contacts and mark polished surfaces in a satisfactory manner³¹.

Two types of paper with different thicknesses and colors can be used in sequence to improve the visualization of these markings. Initially, the patient occludes with a thick paper, from 100 to 200 μm, which produces a broad mark with a central halo without pigment; however, it is covered with a microlayer of the adhesive agent that is capable of optimizing the definition of the mark produced by the following use of a thin paper.

Suggested products (Note: the author has no commercial interest in promoting the products mentioned): Bausch 200 µ Articulating Paper 200 μm (Blue); Bausch Progress 100 100 μm (Red); Bausch 40 µ Micro-Thin Articulating Paper 40 μm (Blue/Red); Bausch Horseshoe-Shape Articulating Paper 40 μm (Blue/Red) (all Jean Bausch, Germany) [Figure 13-02A–G].

[Figure 13-02A–G] Articulating tape made from paper is available in thicknesses from 40 μm and generates greater friction during occlusal contacts, which is effective on polished surfaces.

Polyester articulating tape: These have thicknesses from 8 μm³⁹ and may or may not be impregnated with pigments. They are flexible, resistant to traction, and capable of generating effective markings. They often produce false negatives in the presence of moisture or on highly polished surfaces. It is suggested to apply a thin layer of Vaseline on them to increase the transfer of pigments to the tooth surfaces.

Shimstock (Hanel Coltène/Whaledent, Switzerland) is a metalized polyester tape that is only 8-μm thick, used to verify the presence of simultaneous contacts in CR or MIP⁴⁰. For this, the dentist retains the Shimstock in place with mosquito forceps positioned between the opposing teeth, and asks the patient to occlude [Figure 13-03A,B]. At this point, the dentist makes a slight traction with the forceps to check whether there is an occlusal contact capable of keeping the tape in position. Shimstock is capable of detecting only the presence of a contact, and its location and extent will need to be demarcated with an articulating tape that contains pigments⁴¹.

[Figure 13-03A,B] Shimstock is a metalized polyester tape, 8-μm thick, used to verify the presence of simultaneous contacts in CR or MIP. It should be manipulated with the aid of mosquito forceps when checking for the presence of tooth contacts.

In this author’s experience, a significant number of direct or indirect restorations that appear to be satisfactory according to contact markings remain in supraocclusion, as evidenced by the use of Shimstock on adjacent teeth. In these instances, it will not be retained until the newly restored teeth are fully adjusted. Also, when finalizing an occlusal adjustment in teeth, temporary restorations, or definitive restorations, and within a reorganizing approach, it is suggested to position the Shimstock on both sides simultaneously to attest to the presence of bilateral contacts.

Suggested products (Note: the author has no commercial interest in promoting the products mentioned): Accu-Film II 26 μm (Parkell, USA) (Red/Black); Arti-Fol Metallic 12 μm (Jean Bausch) (Black); TrollFoil Articulating Foil 8 μm (Troll Dental, Sweden) (Blue); Shimstock 8 μm (Hanel Coltène/Whaledent) (no pigment); Shimstock 8 μm (Almore International, USA) (no pigment) [Figure 13-04A–E].

[Figure 13-04A–E] Polyester tapes have thicknesses from 8 μm. They are flexible, resistant to traction, and capable of generating effective markings on different surfaces.

Silk articulating tape: These have thicknesses of around 80 to 90 μm and are flexible and tensile-resistant. The protein fibrils of the natural structure of silk act as a reservoir of an emulsion of pigments based on wax and oils, enabling the effective marking of highly polished surfaces such as ceramics and metals. Although it does not produce false negatives or positives, silk articulating tape generates many markings that are subject to the dentist’s interpretation⁴². Its contact with saliva and soft tissue should be avoided so as not to disperse the pigments.

Suggested products (Note: the author has no commercial interest in promoting the products mentioned): Bausch Articulating Silk 80 μm (Jean Bausch) (Green); Madame Butterfly 90 μm (Almore International) (Green) [Figure 13-05A,B].

[Figure 13-05A,B] Silk tapes have thicknesses around 80 μm and are very effective in transferring the color of their pigments to the occlusal contact areas.

Articulating TAPE forceps

To use most articulating tape, special instruments, called Miller forceps, are required to manipulate the tape safely and accurately. When acquiring these forceps, the dentist should verify whether they can retain even the thinnest articulating tape, because some adjustments are performed with vigorous movements and the tape may become loose during the procedure. Forceps with parallel internal grooves with a precise fit are more effective for this purpose and are recommended by this author [Figure 13-06A–F].

[Figure 13-06A–F] Miller forceps facilitate the manipulation of articulating tape and should easily grip and retain the tape [A–E]. The type with longitudinal grooves is clinically more effective [F].

Electronic tools for the analysis of occlusal contacts

Electronic tools for the qualitative and quantitative analysis of occlusal contacts are available such as T-Scan Novus (Tekscan, USA) or OccluSense (Jean Bausch) [Figure 13-07A,B]. According to the manufacturers, in these systems, electronic sensors of about 60 to 100 μm can record occlusal contacts. These are processed by software that produces didactic graphics containing the location, distribution, magnitude of the force, and exact moment of occlusal contact, in fractions of a second. They can be used for occlusal analysis, occlusal adjustment of single crowns, and complex restorative and orthodontic treatments, and they also differentiate between teeth and implants in terms of pressure.

[Figure 13-07A,B] Electronic tools for the qualitative and quantitative analysis of occlusal contacts, such as the T-Scan Novus (Tekscan) or OccluSense (Jean Bausch), have electronic sensors of about 60 to 100 μm.

Some authors have reported that the thickness and rigidity of the sensors can inhibit proprioception and influence the detection of occlusal contacts^33,40. However, digital devices for evaluating tooth contacts can eliminate the subjectivity of conventional methods³⁶ and provide a refinement of analysis and adjustment. Such equipment requires considerable investment for its acquisition and a learning curve for the operator to use them with maximal efficiency, given the large amount of data generated.

In this author’s opinion, using electronic tools such as T-Scan Novus or OccluSense is valid for the quality and quantity of the information provided. The investment in the equipment will be rewarded with effective occlusal analysis, precise adjustments, and the possibility of monitoring occlusal stability in the long term, resulting in more safety for the dentist.

Occlusal analysis and TRIAL OCCLUSAL ADJUSTMENT on a semi-adjustable articulator (SAA)

Since it is a precise procedure, occlusal adjustment requires a systematic approach in the dental laboratory and clinic. The trial occlusal adjustment with SAA-mounted study models is a valuable tool for evaluating the patient’s occlusion in a three-dimensional (3D) and dynamic way and for anticipating the clinical steps necessary for its adjustment. It helps dentists who have little practical experience to understand mandibular kinematics, and those who are experienced to determine whether the adjustments are clinically advisable, given the magnitude of grinding required to correct the diagnosed functional problems. Solutions to doubts about the possibility of “closing” anterior open bites or resolving significant discrepancies between MIP and CR through occlusal adjustment may also be envisioned.

Analyzing the models mounted in an SAA will allow the identification of the initial points to be adjusted, the prescription of the clinical sequence of adjustments, and how it can be accurately and predictably completed⁴³. It is recommended to note where new interferences are evidenced after each adjustment phase and to pay attention to the extent of selective grinding in order to achieve a satisfactory result. Such an analysis will often anticipate that the adjustment will require many clinical steps and appointments and will also be harmful in terms of wear and tear on the tooth structure. In these situations, the most sensible therapeutic option would be the addition of restorative material, with the possible integration of orthodontic treatment and even orthognathic surgery.

In this author’s opinion, occlusal analysis and a trial occlusal adjustment on the articulator is an excellent strategy for the dentist to improve the science of functional diagnosis and the “art” of occlusal adjustment, recognizing the complexity and irreversibility of the process. According to the planned steps, the dentist should know where to start the adjustments and with what precision and predictability they can be completed.

Sequence of occlusal analysis and SAA TRIAL OCCLUSAL ADJUSTMENT

1. Assemble the study models on the SAA with the aid of a facebow and the registrations in CR. These are limited positions on the articulator from which all mandibular lateral and protrusive movements can be performed [Figure 13-08A–E].

[Figure 13-08A–E] Study models mounted on an SAA with the aid of a facebow and the registrations in CR. It is recommended to perform two to three intermaxillary registrations to enable verification of the accuracy and reproducibility of this procedure in the patient.

2. Lock the condylar components of the SAA in CR (if the articulator used has this feature) to facilitate the manipulation of the articulator. The condylar and Bennett guidance angles should already be calibrated (more details in Chapter 8) [Figure 13-09A,B].

[Figure 13-09A,B] The condylar components of the SAA should be locked in CR (if the articulator used has this feature) to facilitate manipulation of the articulator.

3. Perform the SAA’s short opening and closing movements using a dark articulating tape of 40 to 60 μm, interposed between the maxillary and mandibular models. A horseshoe-shaped tape expedites this process [Figure 13-10].

[Figure 13-10] Perform short opening and closing movements with the SAA, using a dark articulating tape of 40 to 60 μm, interposed between the maxillary and mandibular models.

• Check whether the registration of the models is correct, comparing if the location of the contacts in CR demarcated in the model matches precisely with the contacts in CR highlighted in the mouth [Figure 13-11A,B]. If so, proceed with the analysis and occlusal adjustments. However, suppose the location of the contacts is different. In that case, it is recommended to repeat the intermaxillary registrations and the registration of the mandibular model so that the entire occlusal analysis is not compromised.

[Figure 13-11A,B] Ascertain the accuracy of the registration, comparing whether the location of the contact/s in CR demarcated in the model matches precisely with those in CR highlighted in the mouth. If so, proceed with the analysis and occlusal adjustments.

4. Unlock the condylar components of the SAA in CR.

5. Observe any 3D discrepancy between CR and MIP due to premature contacts interfering with the mandibular closure arch. If so, analyze the magnitude and direction of the displacement of the SAA’s lower frame from these contacts. This information will be helpful, as it predicts the extent of the necessary occlusal changes.

• Observe the dimension of separation of the other teeth when premature contact occurs.
• Loosen the incisal pin fixation screw and adjust the lower frame of the articulator, trying to take the models to the MIP.
• Make the incisal pin rest on the table and re-tighten the fixation screw in the MIP.
• Loosen the incisal pin fixation screw and take the models to CR again, evaluating the degree of opening of the incisal pin in this position. This measurement will correspond to the vertical component of the discrepancy between CR and MIP.

6. Lock the SAA condylar components in CR.

7. Carefully adjust the contacts marked on the model with a Hollenback 3S instrument, a no. 15 scalpel blade, or a rotary cutting instrument. Repeat the marking procedure with articulating tape and adjustments – successively – until bilateral and simultaneous contacts occur and the incisal pin touches the incisal table again in the same VDO of the MIP [Figure 13-12A–P].

[Figure 13-12A–P] The trial occlusal adjustment should be performed on the SAA to assess how much structural addition or removal will be necessary to obtain an adequate distribution of occlusal forces. The contacts marked on the model should be carefully and gradually adjusted with a Hollenback 3S instrument, a no. 15 scalpel blade, or a rotating cutting instrument. In the patient evaluated in this example, after all the adjustments were made on the SAA, it was concluded that adding composite resin in the region of the maxillary canines would increase the effectiveness of the functional guidance.

• Before performing any occlusal adjustment with memorized rules, the dentist should learn to visualize where the lower frame of the articulator moves when premature contact occurs, learning to identify the tooth ridges responsible for the deviations¹. For example, suppose the lower frame – representing the mandible – is anteriorly displaced when hitting the premature contacts. In that case, the distal ridges of the mandibular teeth or the area mesial of the maxillary teeth will be demarcated and should be adjusted [Figure 13-13A–F]. If the lower frame moves to the right, right-facing maxillary tooth ridges or left-facing mandibular tooth ridges should be marked and adjusted. If the shift is to the left, the reverse reasoning should apply [Figure 13-14A-J]. Based on this evaluation, carefully adjust the dental ridges responsible for such mandibular deviations.

  

  [Figure 13-13A–F] The dentist should learn to visualize where the lower frame of the articulator moves when premature contact occurs, learning to identify the aspects of the teeth responsible for the deviations. For example, suppose the lower frame – representing the mandible – is displaced anteriorly. When premature contact occurs, the distal ridges of the mandibular or mesial maxillary teeth will be demarcated and should be adjusted.

  

  [Figure 13-14A–E] If the lower frame shifts to the right [A], the right-facing ridges of the maxillary teeth or left-facing ridges of the mandibular teeth [B,C] should be marked and adjusted [D,E].

  

  [Figure 13-14F–J] If the lower frame shifts to the left, reverse reasoning should be applied.

• Adjustments should be made on the peripheral part of the cusps, bringing the contact marking toward its tip or on the ridges of the opposing fossa or marginal ridges, allowing the contact to approach the fossa or to be over the marginal ridges [Figure 13-15A–D]. Usually, the process of “narrowing” the cusp tip is performed almost simultaneously with the “widening” of the fossa or “flattening” of the opposing marginal ridge, gradually moving the marking to the planned area.

  

  [Figure 13-15A–D] Adjust the peripheral part of the occlusal contacts toward their tip or on the ridges of the opposing fossa or marginal ridges, allowing contact between the fossa or the marginal ridges.

• Cusp tips should not be reduced in height unless they are misaligned with the occlusal plane or interfere with the lateral and protrusive movements [Figure 13-16A–C].

  

  [Figure 13-16A–C] The cusp tips should not be reduced in height unless they are misaligned with the occlusal plane or interfere with lateral and protrusive movements.

• Care should be taken not to damage the anatomy of the cusp, fossa, or marginal ridge. In order to minimize the sacrifice of tooth structure and make the necessary corrections, it is advisable to observe which of the opposing teeth are better aligned to the occlusal plane or which have restorations, adjusting the one that would result in the least structural damage.

8. Unlock the condylar components of the SAA.

9. Evaluate the functional guidance with a red horseshoe-shaped articulating tape of 40 to 60 μm. This will make it easier to analyze the right and left hemiarches simultaneously. The lateral and incisal functional guidance should be smooth and continuous, capable of discluding the posterior teeth during movements of the lower frame of the articulator. When the anatomy of the anterior teeth is satisfactory, interrupted markings or irregular trajectories indicate the presence of posterior interferences [Figure 13-17A–D].

[Figure 13-17A–D] The lateral and incisal functional guidance should be smooth and continuous, capable of discluding the posterior teeth during mandibular movements [A,B]. When the anatomy of the anterior teeth is satisfactory, interrupted markings or irregular trajectories may indicate the presence of posterior interferences [C,D].

• Analyze the magnitude of the necessary adjustments in the posterior teeth for disclusion in lateral and protrusive movements. Often, the anterior teeth show wear and changes in shape or position, rendering them unable to perform such a task. In case of the need for significant adjustments of these posterior contacts, it is essential to consider whether an additive remodeling of the functional guidance with restorative material on the incisors and canines would not be more appropriate for the patient. This test can be performed on the SAA with wax on the teeth in order to plan the quantity and ideal positioning of the restorative material.

10. When deciding on the occlusal adjustment of the posterior teeth, reduce their ridges, preferably the external ones, or widen the fossae that interfere with the lateral and protrusive movements on the non-working and working sides.

• All adjustments of the lateral contacts should be carried out, taking care to preserve the centric contacts marked with a dark articulating tape. It is recommended that the markings of the centric contacts be frequently reinforced, as they guarantee the maintenance of the VDO and tend to fade during manipulation of the articulator.

11. When deciding on the additive remodeling of the functional guidance, minor adjustments to the posterior teeth are usually necessary [Figure 13-18].

[Figure 13-18] When the decision is made to reshape the functional guidance using composite resin or ceramics, fewer occlusal adjustments to the posterior teeth are generally required.

• The functional guidance for lateral movements can be performed by the canines (canine guidance), accompanied or not by the premolars and molars (group function). This author suggests canine guidance for most clinical situations because of its ease of construction, adjustment, and proven effectiveness. Group function cannot be fully adjusted on an SAA due to the limitations of these devices in faithfully reproducing the patient’s lateral and protrusive movements.
• The incisal guidance should be carried out symmetrically by the marginal ridges of the palatal surfaces of the teeth located more anteriorly. In most cases, it is performed by the central incisors, sometimes accompanied by the lateral incisors and, rarely, by the canines⁴⁴ [Figure 13-19A–C].

  

  [Figure 13-19A–C] The incisal guidance should be carried out symmetrically by the lingual marginal ridges of the teeth located more anteriorly, that is, of the central incisors. Sometimes it can be performed in conjunction with the lateral incisors and canines.

• The anterior teeth of the plaster models should be adjusted to the edge-to-edge position, most of the time leaving the incisal edges of the maxillary and mandibular incisors parallel to each other [Figure 13-20A,B].

  

  [Figure 13-20A,B] The anterior teeth should be adjusted to the edge-to-edge position, leaving the incisal edges of the maxillary and mandibular incisors parallel to each other.

Prior patient education

The patient should be made aware that the occlusal adjustment is an essential part of the treatment plan, not a random removal of tooth structure or addition of restorative material. The dentist should invest time in educating and instructing the patient, gaining their confidence by demonstrating the knowledge and expertise necessary for these adjustments. The use of articulator-mounted patient models facilitates understanding and acceptance of the procedure.

It is necessary to explain to the patient that some areas of the teeth that interfere with the correct alignment of the occlusal plane will be adjusted so that function occurs efficiently. During these explanations, it is suggested to avoid the term “grinding” due to its negative connotations of damage or destruction. The patient should know that the adjustments may require a variable time or several appointments until a comfortable and stable result is achieved. It is recommended to avoid long appointments, and it is preferable to make a restricted number of adjustments in appointments of up to 30 minutes. An interval of 7 to 10 days between appointments is recommended to allow a better adaptation of the patient’s stomatognathic system.

The occlusal adjustment in natural teeth is indicated only for areas where the need to remove tooth structure is minimal and in enamel, preferably performed without anesthesia. Depending on the extent of the adjustments or the patient’s sensitivity threshold, the use of an anesthetic may be necessary. The patient needs to be aware that hypersensitivity may follow the adjustments, but that, under normal conditions, this should cease after a few days. When major morphologic modifications are necessary or the adjustment reaches the dentin, a restoration with adhesive material is indicated. Dentin exposure leads to hypersensitivity and increased risk of caries and noncarious lesions through abrasion, attrition, or biocorrosion.

If the dentist or patient is unsure about the effectiveness of the treatment, no irreversible procedure should be performed.

All adjustments should first be performed in a stabilizing interocclusal splint, adjusted according to the goals of the ideal therapeutic reference model. Patients with concerns or symptoms that do not seem related to the existing clinical signs should be treated cautiously, and definitive treatment should not be started. It is also recommended that the patient sign an Informed Consent Form containing the objectives, benefits, risks, and values of the procedure as well as an estimate of the number of sessions required to perform it.

Occlusal adjustment by selective GRINDING in the clinic

In natural teeth, the occlusal adjustment should only be performed after verifying its feasibility and indication from the information obtained through the trial occlusal adjustment using the SAA. In restorative treatments, all the following principles should be used to adjust both the temporary and final restorations.

1. Ask the patient to lie down in a comfortable position, with the head supported and aligned with the body, with no muscle tension [Figure 13-21A–N].

[Figure 13-21A–E] Initial photographs and radiographic examination of a clinical case after orthodontic–surgical treatment.

[Figure 13-21F–H] The esthetic smile project (DSD) is communicated to the dental laboratory technician (DLT) and materialized in the form of temporary restorations.

[Figure 13-21I–N] Composite resin fillings are utilized to restore the tooth substrates. Intraradicular retainers may be indicated when they are deemed necessary [I,J]. Tooth preparations are designed to improve the esthetics and restore the functional parameters [K,L]. Partial and full ceramic veneers are cemented with adhesive resin cement [M,N].

• Evaluate the access of the condyles to the CR position using mandibular manipulation devoid of force, using the technique in which the dentist has the best knowledge and experience^4,24,45. Initially, carefully observe whether there is any deviation when the CR contact occurs. Occlusal deprogramming devices such as a jig², leaf gauge³, or Kois therapeutic deprogrammer^5,6 are recommended in cases where there is a lack of coordination and reproducibility in the patient’s mandibular opening and closing movements. If there is any sign of muscle hyperactivity or discomfort in the TMJs, occlusal adjustment procedures should be postponed until symptoms have ceased and the situation has stabilized.
• The number of occlusal contacts may vary according to the patient’s neuromuscular pattern, their bite force, and the degree of mobility of the teeth^46,47. Therefore, the patient should be asked to perform a repetitive movement of the mandible with similar intensity in order to obtain a consistent pattern of markings.
• Effective humidity control should be ensured by using a high-power suction and successive air spray on the occlusal surfaces. Articulating tapes typically require dry surfaces for maximal effectiveness, as moisture makes it difficult for the marking of the occlusal contacts. Some authors indicate the use of antisialogogues when there is excess salivation, but this does not seem necessary in most cases.
• It is suggested to use a folded gauze to constantly clean the markings from the articulating tape between each step of the adjustments.
• Replace the articulating tape as soon as its shows altered marking ability or is damaged.

2. Mark the CR contacts with a dark tape of 40 to 60 μm [Figure 13-22A–D].

[Figure 13-22A–D] The CR contacts are demarcated and adjusted so that they occur bilaterally and simultaneously, with at least one contact per tooth, as close as possible to the cusp tips or occlusal fossae.

• More important than memorizing rules of occlusal adjustment¹ would be for the dentist to develop a sense of fine 3D perception to observe whether the trajectory of mandibular opening and closing is linear and uniform or where the mandible moves when it touches in premature contact, learning to adjust the aspects responsible for such deviation.
• The CR adjustment procedures should be repeated until bilateral and simultaneous contacts occur in this position. Its precision is of fundamental importance and is directly related to the stability of the treatment.
• Try to position the contacts as close as possible to the cusp tips or occlusal fossae. At least one point of occlusal contact per tooth should occur.

3. Evaluate the functional guidance with a red horseshoe-shaped articulating tape of 40 to 60 μm. This will provide greater ease of analysis of the right and left hemiarches simultaneously. Guidance with interrupted markings or with irregular trajectories indicates the presence of posterior interferences [Figure 13-23A–D].

[Figure 13-23A–D] The functional guidance should be evaluated with a red (or a contrasting color, with centric markings) horseshoe-shaped articulating tape of 40 to 60 μm. This will provide greater ease of analysis of the right and left hemiarches simultaneously.

• When indicated by the diagnostic test, adjust the interfering posterior teeth on the non-working side and the ones on the working side. Do not remove the CR contacts marked with the dark articulating tape.
• It is suggested that the dentist guide the patient’s mandible laterally to restrict laterotrusive movements. The adjustment should be carried out until a uniform and continuous functional guidance is obtained, from centric contact to the canine tips, capable of discluding the posterior teeth during mandibular movements. If the canine is structurally impaired, periodontally compromised, or has been replaced by an implant, the first premolar can be included, and the lateral functional guidance can be turned into a partial group function.
• Adjust the incisal guidance to the edge-to-edge position so that the incisal edges of the mandibular and maxillary incisors are parallel and level, both with each other and with the adopted esthetic references. The distribution of the edge-to-edge contacts between the two central incisors minimizes the stresses on the incisal edges, requiring extra attention in patients with evident wear facets in these areas [Figure 13-24A–F].

  

  [Figure 13-24A–F] The incisal guidance should be adjusted to the edge-to-edge position so that the incisal edges of the mandibular and maxillary incisors are parallel and leveled, both with each other and with the adopted esthetic references. Contacts should be broad and flat in this position.

• Check the presence of posterior interferences with firm mandibular manipulation, pressing the condyle on the working side superiorly to simulate the intense movements present during masticatory function, bruxism, and parafunction. Some interferences will only be evident when manipulating the mandible in this way.

4. Provide an area of freedom in centric, paying particular attention to the anterior teeth, after the centric occlusal contacts and the functional guidance are adjusted [Figure 13-25A–C]. This area will accommodate the minor variations in occlusal contacts resulting from the biologic variability of the TMJs, masticatory muscle activity, head posture, and body position^{1,24,28,48–52}, thus preventing these anterior teeth from having more intense contact than the posterior teeth when the patient is in an upright position or is eating. However, as discussed earlier in this chapter, the interaction between the patient’s head position and occlusal contacts is controversial^53,54, and in this author’s opinion, it is highly recommended that the occlusion be analyzed and appropriately adjusted both with the patient lying down and sitting in the dental chair^51,55.

[Figure 13-25A–C] After the centric occlusal contacts and the functional guidance are adjusted, the need for an anterior area of freedom in centric should be verified by varying the patient’s posture. Thus, in addition to the initial position of the adjustments with the patient lying down, the patient should be asked to sit up and make short and rapid opening and closing movements, tilting the head about 30 degrees forward as if eating a meal.

• For this, the centric contact of the anterior teeth is marked with a dark articulating tape of 12 to 40 μm, with the patient lying down. The dental chair is then placed in an upright position and the patient is asked to sit and make short, rapid opening and closing movements, tilting the head about 30 degrees forward as if eating a meal. At this point, the dentist should touch the anterior teeth with the tips of the index fingers, one by one, trying to ascertain the presence of tooth vibrations, called fremitus, caused by the high intensity of tooth contacts. After tactile analysis, the occlusal contacts should be marked with a thin red articulating tape of 12 to 40 μm. If the previous markings have shifted slightly forward, they should be adjusted to maintain the same horizontal plane and eliminate any fremitus that may be present.

5. Assess the need to adjust the extreme excursive movement (cross-over^56–58). This is a borderline movement⁵⁹, verified by the evaluation of the attrition pattern present in the patient during the functional examination. Since the incisal edges of the mandibular teeth surpass those of the maxillary teeth in this movement, wear or chips in the incisobuccal angles of the maxillary anterior teeth or the incisolingual angles of the mandibular teeth are identified. In these patients, the angles mentioned above should be slightly rounded so as not to restrict such movements⁵⁷ [Figure 13-26A–C].

[Figure 13-26A–C] Adjustment of extreme excursive movement (cross-over) is performed in those patients who have been shown to have a parafunctional pattern of mandibular movement during the functional clinical examination. In these individuals, the incisobuccal angles of the maxillary anterior teeth or the incisolingual angles of the mandibular teeth should be adjusted and slightly rounded so as not to restrict mandibular movements.

6. Perform the functional adjustment of mastication: Up until now, all adjustments have been made with the same excursive movements used on the articulator, from the inside to the outside. For a complete adjustment, it is of fundamental importance that a refinement is made according to the patient’s masticatory cycle^60–64, allowing both excursive and incursive mandibular movements – without restrictions – close to the MIP¹. Although it is not discussed much in the literature, this adjustment increases occlusal stability and patient comfort and minimizes the risk of failure of restorative materials [Figure 13-27A–C].

[Figure 13-27A–C] The occlusal adjustment should be refined according to the incursive mandibular movements that constitute mastication and may also be part of parafunctional activities. For this, ask the patient to simulate the chewing process with an articulating tape, preferably thick and horseshoe-shaped, interposed between the dental arches. The resulting markings will generally be more intense due to the relevant activity of the jaw elevator muscles during these movements.

• With the patient seated, place a red horseshoe-shaped articulating tape of 100 μm over the dental arch and ask the patient to “chew” it on the right side, as if it were chewing gum. This movement simulates the masticatory cycle, which has natural movements of mandibular incursion from the outside to the inside and force amplified by the contraction of the jaw elevator muscles^62,65 (more details in Chapter 9). Furthermore, this simulated chewing process allows the detection of interferences that had not been identified until this time.
• Using the strategy described above, keep the centric contacts demarcated by the dark articulating tape and remove only the unwanted contacts on the posterior teeth highlighted in red, both on the non-working and working sides. Regarding the functional guidance, the smoothed trajectories in the canines should be maintained in the occlusal scheme with canine guidance; alternatively, equalize the forces on the teeth participating in the group function occlusal scheme. Repeat the procedure in the same way again for the left side.
• With the same thick articulating tape positioned between the arches, ask the patient to position the mandible forward and simulate food incision movements. More intense markings can appear on both the anterior and posterior teeth due to the contraction of the elevator muscles resulting from this activity. If necessary, adjust the interferences of the posterior teeth without removing the centric contacts, and refine the adjustment of the lingual surface of the maxillary teeth and incisal edges of the mandibular teeth, maintaining the stabilizing centric contacts.

7. Ensure that all occlusal adjustments are performed as planned at this appointment. The dentist needs to consider that inadequate or incomplete adjustments promote the removal of tooth structure as well as potentially create new interferences, activating occlusal awareness and adaptive responses of the patient such as discomfort, pain, or dysfunction^1,24,28,29.

The following criteria are recommended for gauging the completeness of the occlusal adjustment through the senses of sight, hearing, and touch⁶⁶:

• Sight: Observe whether the patient moves the mandible without hesitation, abrupt movements, or deviations. Also, analyze whether the markings obtained with the articulating tape are regular, uniformly distributed, and well positioned.
• Hearing: Detect whether the sounds coming from the tooth contacts are distinct and clear, or whether they reveal some slipping or “galloping” sounds.
• Touch: Check for fremitus, that is, feel with the tips of the index fingers whether some of the teeth vibrate during occlusal contact. Also, tactilely, test the occurrence of simultaneous bilateral contacts with the use of Shimstock. All posterior teeth and canines should hold Shimstock under a light bite force.
• Individual occlusal sensitivity: Ask whether the patient feels comfortable with their bite, with both light and intense bite forces.

8. Meticulously polish all adjusted areas with sequential abrasive tips and diamond-impregnated pastes to restore the texture and smoothness of the enamel or restorative material and minimize friction between surfaces.

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