Prosthodontic anterior William Wilford
treatment
of traumatic
overlap
of the
teeth B. Akerly, Hall
USAF
D.D.S., M.S.* Medical
Center,
San Antonio,
Texas
lh e treatment of patients with excessive overlap of anterior teeth has always been a challenge to the dentist. Some patients are fortunate to have received early preventive care, while others function adequately with no disturbing symptoms. A third group, however, develops signs and symptoms of trauma from occlusion. This latter group tests our skills in delivery of definitive treatment. Frequently, the only treatment is to relieve subjective symptoms. Many such patients develop psychological defenses against dentistry and their appearance as a result of palliative treatments, progressive dental disease, and undesirable esthetics. To facilitate diagnosis and treatment planning, patients with traumatic overlap of the anterior teeth can be divided into four types (Figs. 1 to 4). Although most problems are interrelated, each type has distinct characteristics and requires different treatment approaches.
TRAUMATIC OVERLAP OF THE ANTERIOR TEETH Terminology. Overlap is the extension of the upper teeth over the lower teeth in a vertical or horizontal direction when the teeth are in centric occlusion.1 The position and morphology of the lingual surfaces of the maxillary anterior teeth in most instances dictate the path of the mandibular incisors during eccentric movements of the mandible. This influence is referred to as incisal guidance. Variations in overlap. Average vertical overlap is defined anatomically as coverage of one third of the mandibular incisors by the maxillary incisors when the teeth are in occlusion.2 An infinite number of variations can occur in horizontal and vertical overlap of the anterior teeth. Variations most often result from disproportionate growth of the bones of the upper face, the mandible, or the alveolar processes.3 An excessive amount of horizontal overlap may result from maxillary prognathism or from a retrognathic mandible. The amount of horizontal overlap also varies with differences in alveolar prognathism or as a result of differences in inclination of either the maxillary or the mandibular incisors. The amount of vertical overlap has an in*Colonel,
26
USAF
(DC)
; Department
of Prosthodontics.
Prosthodontic
treatment
of traumatic
overlap
of
teeth
27
Fig. 1. Type I traumatic overlap. The mandibular incisors extrude and impinge into the palate. Fig. 2. Type II traumatic overlap. The mandibular incisors impinge into the gingival sulcus of the maxillary incisors.
Fig. 3. Type III
traumatic
overlap. Both
with
on tissues
of each arch.
impingement
Fig. 4. Type IV traumatic overlap. The lingual surfaces of the maxillary teeth. fluence on the amount tions can change with teeth.
maxillary mandibular
and teeth
mandibular move
incisors or extrude
incline into
and degree of horizontal overlap. Finally, overlap alterations in occlusion caused by wear, movement,
lingually the abraded
configuraor loss of
Defining traumatic overlap. Horizontal or vertical overlap of the anterior teeth is not, in itself, a reliable indicator as to whether a dentition will be healthy or pathologic. Excessive overlap of the anterior teeth can exist in all of Angle’s three classes of malocclusion.4 The degree of incisal guidance, as derived from the character of horizontal and vertical overlap of the anterior teeth, is not important for a harmonious neuromuscular relationship.6 Thus, extreme variations in horizontal and vertical overlap can be present in clinically healthy dentitions.
28
Akerly
J, Prosthet. Dent. July, 1977
The term, “trauma,” refers to actual alterations of tissue produced by dental disharmony.G The tissue changes most likely to result from traumatic overlap of the anterior teeth are resorption of alveolar bone, abnormal wear of the teeth, and mucosal or gingival abrasion. Periodontitis often coexists with trauma from severe overlap, and traumatic forces may accelerate the progress of periodontal disease. Clinical signs and symptoms. The most frequent clinical signs of traumatic overlap are abrasion, mobility, and displacement or migration of the teeth. There also may be inflammation, swelling, and ulceration of the gingival and palatal mucosae. The patient frequently complains that spaces have recently developed between two or more anterior teeth or that teeth have been displaced labially. Subjective symptoms may include intermittent episodes of pain related to gingival or mucosal irritation or pain from acute periodontal abscesses. Rapid abrasion or erosion of tooth structure may result in pain from thermal or frictional stimuli.
ETIOLOGY OF TRAUMATIC ANTERIOR OCCLUSION Malocclusion. The Angle Class II, division 1 or 2, malocclusion most often predisposes to traumatic overlap of the anterior teeth. However, traumatic overlap can develop with any type of malocclusion, especially when the posterior occlusion is deficient as a result of missing or malpositioned teeth. Extrusion. Teeth which lack functional antagonists have the potential to extrude. Extruded teeth contribute to impaction of food and can cause irritation of the mucosa and ocdusal disharmony. Bilateral functional movements of the mandible may be impaired as a result of protective neuromuscular reflexes. This inhibition of functional movement contributes to progressive malposition of the teeth or uneven wear patterns. Periodontitis. Periodontitis may account for the loss of posterior teeth and thus can generate traumatic forces anteriorly. Bone loss from periodontitis of the maxillary anterior teeth leads to mucosal changes and permits extrusion of the mandibular teeth. Loss of teeth. Loss of teeth as a result of periodontal disease and caries, or loss of tooth structure as a result of abrasion and erosion, contributes to the generation of traumatic forces anteriorly, The loss of posterior teeth predisposes to intrusion or tipping of the remaining teeth. Deflective occlusion. The deflective occlusal contacts so often demonstrated in clinically healthy dentitions are potentially traumatic to the anterior teeth. These contacts most frequently occur on the mesial inclines of the maxillary cusps and the distal inclines of the mandibular cusps. An increase in the magnitude of deflection resulting from changes in posterior occlusion can cause traumatic forces anteriorly. On the other hand, a change in overlap as a result of extrusion of the anterior teeth can cause a small amount of deflection to become traumatic. Decreased vertical dimension of occlusion. A decrease in the vertical dimension of occlusion can result from the loss of posterior teeth or from the wear of teeth without compensatory eruption. When the mandible overcloses, the mandibular incisors move anteriorly as well as superiorly.7 This anterior advance of the incisors can cause the signs and symptoms of traumatic overlap. Since the maxillary incisors incline opposite to the mandibular incisors, the slightest overclosure may result in traumatic contact.
Prosthodontic
Fig. 5A. Displeasing esthetics resulting I traumatic overlap.
treatment
in psychological
01 traumatic
overlap
of teeth
29
defense is a common finding in Type
Fig. 5B. In Type I traumatic overlap, incisor occlusion is restored with a metallic connector of a removable partial denture.
SEQUENCE OF TRAUMATIC EVENTS The event.s leading to traumatic overlap do not occur overnight, but rather over many years. In most instances, the events are cyclical and c:ompounding. Malocclusion, caries, and periodontal disease contribute to loss of teeth and subsequent loss of posterior occlusal support. A more severe malocclusion develops as a result of extrusion of teeth. Deflective occlusion becomes a, significant factor in delivering forces of a traumatic magnitude. Further bone loss, wear, and displacement of teeth lead to collapse of the OCC~Usion. The loss of vertical dimension causes the mandible to overclose, and the remaining teeth move forward as well as upward during this rnovement of mandibular advance. All these factors contribute to further malocclusion, periodontal pathology, and traumatic overlap of the anterior teeth.
TREATMENT CONSIDERATIONS Since the etiology of traumatic overlap often clusion, orthodontic and/or surgical management
includes a developmental malocis the treatment of choice. Many
30
J. Prosthet. Dent. July, 1977
Akerly
Fig. 6. lap. (B) interfere
(A) Traumatic Treatment with anterior
forces can cause marked separation of teeth in Type II traumatic overof Type II traumatic overlap should not change vertical dimension or guidance in protrusive or lateral excursions.
severe overlap problems could be prevented by early orthodontic diagnosis and treatment. The possibility of orthognathic surgery should also be considered in planning treatment. By the time patients are referred for prosthodontic treatment of traumatic overlap of the anterior teeth, the clinical symptoms are usually well advanced. These symptoms often include occlusal collapse and hopeless teeth which are indicated for extraction. The prosthodontist is often challenged to formulate intelligent compromises, since there are no simple solutions to treatment. Definitive, transitional, or palliative treatment. Patients with traumatic overlap often have a past history of neglect and poor dental health. Definitive treatment of a reconstructive or elaborate nature is not indicated until after thorough study, analysis, and observation of the patient’s health and behavior. Transitional treatment can be for either a short or an indefinite period of time; and it should be based on a knowledge that eventual deterioration and future loss of teeth will lead to changes in or replacement of the prostheses. Palliative treatment results only in the relief of symptoms, a fact which should be understood by the patient.
TYPES OF TRAUMATIC OVERLAP Type I traumatic overlap. Malocclusion and impingement of the mandibular incisors into the palate are characteristic of the Type I overlap problem (Fig. 1). A long-standing dissatisfaction with esthetics on the part of the patient is a common finding, and psychological defenses which affect his personality and behavior may have developed (Fig. 5A). Patients often develop an indifferent attitude toward oral hygiene and dental treatment. In many instances, this attitude is reversible with counseling. Factors such as rampant caries, periodontitis, number of teeth present, and the patient’s attitude and desires will influence the planning of treatment. When a complete denture is indicated, a combination of alveolectomy and collapse of the maxillary labial plate of bone may be necessary to change the position of the maxillary anterior teeth. For optimum esthetics and physiologic function, more than the average amount of overlap should be maintained, since the basic jaw discrepancy has not been corrected. There is often a marked improvement in the patient’s attitude following initial
Prosthodontic
Fig. 7. fAi be provided tation.
t
rlap
Severe extrusion with resistance to periodontitis on the restorations, and the mandibular incisors
Fig. 8. (A) The possible to create may be necessary
extreme vertical overlap of Type III stops in crowns. CB) A slight increase in this type of overlap situation.
of
teeth
31
and displacement. fB1 Stops must are adjusted at the time of cemen-
traumatic overlap makes in the vertical dimension
it almost imof occmsion
prosthodontic treatment. For this reason, only the hopeless teeth should be extracted during the early phases of treatment. When multiple maxillary and mandibular teeth are retainable, the major connector of an upper removable partial denture can provide occlusion with the mandibular incisors (Fig. 5B). The major connector should be thin and designed with no change in the vertical dimension of occlusion. The extruded mandibular incisors should be modified to accommodate the thickness of the metal in the pal.ate. When components of the prosthesis are used for occlusal guidance or when I:he interocclusal space is restricted, the occlusal surfaces should be protected with metal. Type ZZ traumatic overlap. The incisal edges of the mandibular incisors impinge into the gingival sulcus of the maxillary incisors (Fig. 2). The plunger action of the mandibular incisors aggravates the signs and symptoms of traumatic overlap, as well as the progress of periodontitis. Traumatic forces associated with extrusion, impingement, and bruxism can cause marked separation of teeth (Fig. 6, A). If prosthodontic treatment of a traumatic overlap problem is to be definitive, the denture must be strong and durable. A removable partial denture should not yield or wear under occlusal function. Several advantages result from using metal back-
32
J. Yrosthet. Dent. July, 1977
Akerly
Fig. 9A. The mandibular opposing teeth.
incisors move or extrude
into the abraded lingual
surfaces of the
Fig. 9B. Deflective occlusion and possible loss of vertical dimension of occlusion contribute Type IV traumatic overlap.
to
ings to replace anterior teeth. Metal backings provide a planned guidance, protect the artificial teeth, and prevent extrusion of opposing teeth (Fig. 6, B) . Patients prefer metal backings because they are less bulky and have better thermal conductivity in the region adjacent to the facings. The selected teeth must be arranged and tried in the mouth, and sufficient space for an adequate thickness of metal must be provided. Occasionally, a patient with a Type II overlap problem demonstrates a resistance to periodontitis and still has the signs and symptoms of traumatic overlap (Fig. 7, A). Usually, there is a history of repeated replacement of individual defective restorations and palliative treatment to relieve pain from impingement of the mandibular incisors. A chronic hyperplastic gingivitis may have developed in response to years of irritation. Periodontal treatment should be completed prior to restorative treatment. If restorative treatment is to be definitive, the mandibular incisors must be prevented from extruding. Extrusion can be prevented by designing definite occlusal seats on opposing restorations. A lingual plate connector on a mandibular removable prosthesis will also prevent eruption of the mandibular incisors, if it fits precisely. The technical phases of construction of all restorations for overlap problems must
Prosthodontic
treatment
of traumatic
Fig. 9C. Favorable guidance and contours can be established centric relation at the proper vertical dimension.
overlap
by restoring
of teeth
the mandible
33
to
be closely coordinated with the laboratory. After mounting the casts in centric relation, the mandibular incisors are adjusted to provide space for odd 1edgrz.s on the opposing castings (Fig. 7, B) . Excessive vertical overlap is often a limiting factor in achieving an optimum incisal guidance. When gingival seats are created for definite occlusion, a degree of freedom should be included in the restorations. The steepness of the incisal guidance should be reduced by increasilng the horizontal overlap, as allowed by esthetic requirements. The gingival one third of the restorations should not be overcontoured any more than necessary to provide definite seats. After inserting the restorations, the incisal edges of the mandibular teeth are adjusted to the level that was programmed in the laboratory. It may be necessary to anesthetize the teeth for this adjustment, but continued sensitivity is rarely a problem. Type III traumatic overlap. The third type of traumatic overlap develops as a result of an Angle Class II, division 2, malocclusion. Both maxillary and mandibular incisors are usually inclined lingually (Fig. 3) Fortunately, this type of patient has a large interocclusal distance. If treatment is by means of removable prosthodontics, there is often no choice but to increase the vertical dimension of occlusion (Fig. 8, A and B). Periodontal pathosis and abrasion often accompany the severe extrusion. Posterior occlusion is usually deficient as a result of the malocclusion. If the trauma is limited to the anterior teeth and there is no indication to restore posterior occlusion, the mandibular incisors can be reduced anId the maxillary incisors can be restored with lingual ledges. With more advanced trauma and loss of posterior occlusion, a removable prosthesis is usually required. A lingual plate connector on a mandibular partial denture will deter extrusion of the mandibular incisors. Since the large interocclusal distance developed with the malocclusion is used to eat, breathe, and speak and since a prosthesis does not treat the basic malocclusion, any increase in the vertical dimension of occlusion should be minimized. Type IV traumatic ouerlap. The fourth type of traumatic roverlap is characterized by the movement or extrusion of the mandibular teeth into the abraded lingual surface of the maxillary teeth (Fig. 4). This is the most confusing of the four types of as a result of changes in the posterior occlusion, traumatic overlap. It usually ckvelops rather than from the deterioration of an abnormality in growth and development. Abrasion, erosion, and loss of vertical dimension of occlusion are characteristic of this type of traumatic overlap (Fig. 9A).
34
J. Prosthet.
Akerly
Dent.
July, 1977
There may be a loss of occlusal vertical dimension as a result of wear, erosion, or loss of teeth if there is no compensatory eruption. The goal of treatment is to restore lost vertical dimension of occlusion. In restoring the mandible to the proper vertical dimension in centric relation, the excessive overlap problem is usually eliminated (Figs. 9B and 9C). The restoration of occlusal vertical dimension and the elimination of deflective occlusal contacts are the keys to treating the fourth type of traumatic overlap problem.
SUMMARY AND CONCLUSIONS It is helpful to categorize patients with traumatic overlap of the anterior teeth into four types. The numerous etiologic factors must be analyzed to arrive at a logical treatment plan and a definitive prognosis. 1. The tendency for extrusion is common to all types of traumatic overlap. 2. Psychological problems as a result of esthetic and phonetic dissatisfaction are most characteristic of the Type I traumatic overlap problem. 3. The traumatic forces from the overlap relationships of Types I and II may accelerate the progress of periodontitis. 4. An increase in the vertical dimension of occlusion, solely for the purpose of accommodating a prosthesis, should be limited to the third type of traumatic overlap. 5. If the vertical dimension of occlusion must be increased, the increase should not exceed that necessary to accommodate a prosthesis. Prosthodontic treatment does not treat the basic malocclusion of the patient. 6. When diagnostic findings indicate that the vertical dimension of occlusion has decreased, then the vertical dimension of occlusion should be restored prior to or concurrent with the restoration of the anterior teeth. 7. The removal of deflective occlusal contacts and the restoration of occlusion in centric relation should be routine treatment for patients with traumatic overlap of the anterior teeth. 8. Prosthodontic restorations should be designed to deter extrusion and movement of the teeth- and also restore function in a definitive manner.
References 1. 2. 3. 4. 5. 6. 7.
Boucher, Mosby Sicher, Company, Sicher, Sicher, Ramfjord, Company, Boucher, Mosby Goodkind,
C. 0.: Current Clinical Company, p. 282. H., and DuBrul, E. L.: p. 262. H.: Oral Anatomy, ed. H.: Oral Anatomy, ed. S. P., and Ash, M. p. 2 11. C. 0.: Current Clinical Company, p. 415. R. J.: Mandibular
PROSTHET. DENT. 18: 438-447, 12814 KINGS FORREST SAN ANTONIO, TEXAS 78230
Dental Oral
Terminology,
Anatomy,
ed. 2, St. Louis,
ed. 5, St. Louis,
3, St. Louis, 1960, The C. V. Mosby 3, St. Louis, 1960, The C. V. Mosby M.: Occlusion, ed. 2, Philadelphia, Dental Movement 1967.
Terminology, With
Changes
1970,
the
The
Vertical
The
C. V.
Company, Company, 1971, W.
ed. 2, St. Louis, in
1974,
1974,
C.
V.
Mosby
p. 132. p. 133. B. Saunders The
Dimension,
C. V. J.
treatment
of traumatic
overlap
of the
teeth B. Akerly, Hall
USAF
D.D.S., M.S.* Medical
Center,
San Antonio,
Texas
lh e treatment of patients with excessive overlap of anterior teeth has always been a challenge to the dentist. Some patients are fortunate to have received early preventive care, while others function adequately with no disturbing symptoms. A third group, however, develops signs and symptoms of trauma from occlusion. This latter group tests our skills in delivery of definitive treatment. Frequently, the only treatment is to relieve subjective symptoms. Many such patients develop psychological defenses against dentistry and their appearance as a result of palliative treatments, progressive dental disease, and undesirable esthetics. To facilitate diagnosis and treatment planning, patients with traumatic overlap of the anterior teeth can be divided into four types (Figs. 1 to 4). Although most problems are interrelated, each type has distinct characteristics and requires different treatment approaches.
TRAUMATIC OVERLAP OF THE ANTERIOR TEETH Terminology. Overlap is the extension of the upper teeth over the lower teeth in a vertical or horizontal direction when the teeth are in centric occlusion.1 The position and morphology of the lingual surfaces of the maxillary anterior teeth in most instances dictate the path of the mandibular incisors during eccentric movements of the mandible. This influence is referred to as incisal guidance. Variations in overlap. Average vertical overlap is defined anatomically as coverage of one third of the mandibular incisors by the maxillary incisors when the teeth are in occlusion.2 An infinite number of variations can occur in horizontal and vertical overlap of the anterior teeth. Variations most often result from disproportionate growth of the bones of the upper face, the mandible, or the alveolar processes.3 An excessive amount of horizontal overlap may result from maxillary prognathism or from a retrognathic mandible. The amount of horizontal overlap also varies with differences in alveolar prognathism or as a result of differences in inclination of either the maxillary or the mandibular incisors. The amount of vertical overlap has an in*Colonel,
26
USAF
(DC)
; Department
of Prosthodontics.
Prosthodontic
treatment
of traumatic
overlap
of
teeth
27
Fig. 1. Type I traumatic overlap. The mandibular incisors extrude and impinge into the palate. Fig. 2. Type II traumatic overlap. The mandibular incisors impinge into the gingival sulcus of the maxillary incisors.
Fig. 3. Type III
traumatic
overlap. Both
with
on tissues
of each arch.
impingement
Fig. 4. Type IV traumatic overlap. The lingual surfaces of the maxillary teeth. fluence on the amount tions can change with teeth.
maxillary mandibular
and teeth
mandibular move
incisors or extrude
incline into
and degree of horizontal overlap. Finally, overlap alterations in occlusion caused by wear, movement,
lingually the abraded
configuraor loss of
Defining traumatic overlap. Horizontal or vertical overlap of the anterior teeth is not, in itself, a reliable indicator as to whether a dentition will be healthy or pathologic. Excessive overlap of the anterior teeth can exist in all of Angle’s three classes of malocclusion.4 The degree of incisal guidance, as derived from the character of horizontal and vertical overlap of the anterior teeth, is not important for a harmonious neuromuscular relationship.6 Thus, extreme variations in horizontal and vertical overlap can be present in clinically healthy dentitions.
28
Akerly
J, Prosthet. Dent. July, 1977
The term, “trauma,” refers to actual alterations of tissue produced by dental disharmony.G The tissue changes most likely to result from traumatic overlap of the anterior teeth are resorption of alveolar bone, abnormal wear of the teeth, and mucosal or gingival abrasion. Periodontitis often coexists with trauma from severe overlap, and traumatic forces may accelerate the progress of periodontal disease. Clinical signs and symptoms. The most frequent clinical signs of traumatic overlap are abrasion, mobility, and displacement or migration of the teeth. There also may be inflammation, swelling, and ulceration of the gingival and palatal mucosae. The patient frequently complains that spaces have recently developed between two or more anterior teeth or that teeth have been displaced labially. Subjective symptoms may include intermittent episodes of pain related to gingival or mucosal irritation or pain from acute periodontal abscesses. Rapid abrasion or erosion of tooth structure may result in pain from thermal or frictional stimuli.
ETIOLOGY OF TRAUMATIC ANTERIOR OCCLUSION Malocclusion. The Angle Class II, division 1 or 2, malocclusion most often predisposes to traumatic overlap of the anterior teeth. However, traumatic overlap can develop with any type of malocclusion, especially when the posterior occlusion is deficient as a result of missing or malpositioned teeth. Extrusion. Teeth which lack functional antagonists have the potential to extrude. Extruded teeth contribute to impaction of food and can cause irritation of the mucosa and ocdusal disharmony. Bilateral functional movements of the mandible may be impaired as a result of protective neuromuscular reflexes. This inhibition of functional movement contributes to progressive malposition of the teeth or uneven wear patterns. Periodontitis. Periodontitis may account for the loss of posterior teeth and thus can generate traumatic forces anteriorly. Bone loss from periodontitis of the maxillary anterior teeth leads to mucosal changes and permits extrusion of the mandibular teeth. Loss of teeth. Loss of teeth as a result of periodontal disease and caries, or loss of tooth structure as a result of abrasion and erosion, contributes to the generation of traumatic forces anteriorly, The loss of posterior teeth predisposes to intrusion or tipping of the remaining teeth. Deflective occlusion. The deflective occlusal contacts so often demonstrated in clinically healthy dentitions are potentially traumatic to the anterior teeth. These contacts most frequently occur on the mesial inclines of the maxillary cusps and the distal inclines of the mandibular cusps. An increase in the magnitude of deflection resulting from changes in posterior occlusion can cause traumatic forces anteriorly. On the other hand, a change in overlap as a result of extrusion of the anterior teeth can cause a small amount of deflection to become traumatic. Decreased vertical dimension of occlusion. A decrease in the vertical dimension of occlusion can result from the loss of posterior teeth or from the wear of teeth without compensatory eruption. When the mandible overcloses, the mandibular incisors move anteriorly as well as superiorly.7 This anterior advance of the incisors can cause the signs and symptoms of traumatic overlap. Since the maxillary incisors incline opposite to the mandibular incisors, the slightest overclosure may result in traumatic contact.
Prosthodontic
Fig. 5A. Displeasing esthetics resulting I traumatic overlap.
treatment
in psychological
01 traumatic
overlap
of teeth
29
defense is a common finding in Type
Fig. 5B. In Type I traumatic overlap, incisor occlusion is restored with a metallic connector of a removable partial denture.
SEQUENCE OF TRAUMATIC EVENTS The event.s leading to traumatic overlap do not occur overnight, but rather over many years. In most instances, the events are cyclical and c:ompounding. Malocclusion, caries, and periodontal disease contribute to loss of teeth and subsequent loss of posterior occlusal support. A more severe malocclusion develops as a result of extrusion of teeth. Deflective occlusion becomes a, significant factor in delivering forces of a traumatic magnitude. Further bone loss, wear, and displacement of teeth lead to collapse of the OCC~Usion. The loss of vertical dimension causes the mandible to overclose, and the remaining teeth move forward as well as upward during this rnovement of mandibular advance. All these factors contribute to further malocclusion, periodontal pathology, and traumatic overlap of the anterior teeth.
TREATMENT CONSIDERATIONS Since the etiology of traumatic overlap often clusion, orthodontic and/or surgical management
includes a developmental malocis the treatment of choice. Many
30
J. Prosthet. Dent. July, 1977
Akerly
Fig. 6. lap. (B) interfere
(A) Traumatic Treatment with anterior
forces can cause marked separation of teeth in Type II traumatic overof Type II traumatic overlap should not change vertical dimension or guidance in protrusive or lateral excursions.
severe overlap problems could be prevented by early orthodontic diagnosis and treatment. The possibility of orthognathic surgery should also be considered in planning treatment. By the time patients are referred for prosthodontic treatment of traumatic overlap of the anterior teeth, the clinical symptoms are usually well advanced. These symptoms often include occlusal collapse and hopeless teeth which are indicated for extraction. The prosthodontist is often challenged to formulate intelligent compromises, since there are no simple solutions to treatment. Definitive, transitional, or palliative treatment. Patients with traumatic overlap often have a past history of neglect and poor dental health. Definitive treatment of a reconstructive or elaborate nature is not indicated until after thorough study, analysis, and observation of the patient’s health and behavior. Transitional treatment can be for either a short or an indefinite period of time; and it should be based on a knowledge that eventual deterioration and future loss of teeth will lead to changes in or replacement of the prostheses. Palliative treatment results only in the relief of symptoms, a fact which should be understood by the patient.
TYPES OF TRAUMATIC OVERLAP Type I traumatic overlap. Malocclusion and impingement of the mandibular incisors into the palate are characteristic of the Type I overlap problem (Fig. 1). A long-standing dissatisfaction with esthetics on the part of the patient is a common finding, and psychological defenses which affect his personality and behavior may have developed (Fig. 5A). Patients often develop an indifferent attitude toward oral hygiene and dental treatment. In many instances, this attitude is reversible with counseling. Factors such as rampant caries, periodontitis, number of teeth present, and the patient’s attitude and desires will influence the planning of treatment. When a complete denture is indicated, a combination of alveolectomy and collapse of the maxillary labial plate of bone may be necessary to change the position of the maxillary anterior teeth. For optimum esthetics and physiologic function, more than the average amount of overlap should be maintained, since the basic jaw discrepancy has not been corrected. There is often a marked improvement in the patient’s attitude following initial
Prosthodontic
Fig. 7. fAi be provided tation.
t
rlap
Severe extrusion with resistance to periodontitis on the restorations, and the mandibular incisors
Fig. 8. (A) The possible to create may be necessary
extreme vertical overlap of Type III stops in crowns. CB) A slight increase in this type of overlap situation.
of
teeth
31
and displacement. fB1 Stops must are adjusted at the time of cemen-
traumatic overlap makes in the vertical dimension
it almost imof occmsion
prosthodontic treatment. For this reason, only the hopeless teeth should be extracted during the early phases of treatment. When multiple maxillary and mandibular teeth are retainable, the major connector of an upper removable partial denture can provide occlusion with the mandibular incisors (Fig. 5B). The major connector should be thin and designed with no change in the vertical dimension of occlusion. The extruded mandibular incisors should be modified to accommodate the thickness of the metal in the pal.ate. When components of the prosthesis are used for occlusal guidance or when I:he interocclusal space is restricted, the occlusal surfaces should be protected with metal. Type ZZ traumatic overlap. The incisal edges of the mandibular incisors impinge into the gingival sulcus of the maxillary incisors (Fig. 2). The plunger action of the mandibular incisors aggravates the signs and symptoms of traumatic overlap, as well as the progress of periodontitis. Traumatic forces associated with extrusion, impingement, and bruxism can cause marked separation of teeth (Fig. 6, A). If prosthodontic treatment of a traumatic overlap problem is to be definitive, the denture must be strong and durable. A removable partial denture should not yield or wear under occlusal function. Several advantages result from using metal back-
32
J. Yrosthet. Dent. July, 1977
Akerly
Fig. 9A. The mandibular opposing teeth.
incisors move or extrude
into the abraded lingual
surfaces of the
Fig. 9B. Deflective occlusion and possible loss of vertical dimension of occlusion contribute Type IV traumatic overlap.
to
ings to replace anterior teeth. Metal backings provide a planned guidance, protect the artificial teeth, and prevent extrusion of opposing teeth (Fig. 6, B) . Patients prefer metal backings because they are less bulky and have better thermal conductivity in the region adjacent to the facings. The selected teeth must be arranged and tried in the mouth, and sufficient space for an adequate thickness of metal must be provided. Occasionally, a patient with a Type II overlap problem demonstrates a resistance to periodontitis and still has the signs and symptoms of traumatic overlap (Fig. 7, A). Usually, there is a history of repeated replacement of individual defective restorations and palliative treatment to relieve pain from impingement of the mandibular incisors. A chronic hyperplastic gingivitis may have developed in response to years of irritation. Periodontal treatment should be completed prior to restorative treatment. If restorative treatment is to be definitive, the mandibular incisors must be prevented from extruding. Extrusion can be prevented by designing definite occlusal seats on opposing restorations. A lingual plate connector on a mandibular removable prosthesis will also prevent eruption of the mandibular incisors, if it fits precisely. The technical phases of construction of all restorations for overlap problems must
Prosthodontic
treatment
of traumatic
Fig. 9C. Favorable guidance and contours can be established centric relation at the proper vertical dimension.
overlap
by restoring
of teeth
the mandible
33
to
be closely coordinated with the laboratory. After mounting the casts in centric relation, the mandibular incisors are adjusted to provide space for odd 1edgrz.s on the opposing castings (Fig. 7, B) . Excessive vertical overlap is often a limiting factor in achieving an optimum incisal guidance. When gingival seats are created for definite occlusion, a degree of freedom should be included in the restorations. The steepness of the incisal guidance should be reduced by increasilng the horizontal overlap, as allowed by esthetic requirements. The gingival one third of the restorations should not be overcontoured any more than necessary to provide definite seats. After inserting the restorations, the incisal edges of the mandibular teeth are adjusted to the level that was programmed in the laboratory. It may be necessary to anesthetize the teeth for this adjustment, but continued sensitivity is rarely a problem. Type III traumatic overlap. The third type of traumatic overlap develops as a result of an Angle Class II, division 2, malocclusion. Both maxillary and mandibular incisors are usually inclined lingually (Fig. 3) Fortunately, this type of patient has a large interocclusal distance. If treatment is by means of removable prosthodontics, there is often no choice but to increase the vertical dimension of occlusion (Fig. 8, A and B). Periodontal pathosis and abrasion often accompany the severe extrusion. Posterior occlusion is usually deficient as a result of the malocclusion. If the trauma is limited to the anterior teeth and there is no indication to restore posterior occlusion, the mandibular incisors can be reduced anId the maxillary incisors can be restored with lingual ledges. With more advanced trauma and loss of posterior occlusion, a removable prosthesis is usually required. A lingual plate connector on a mandibular partial denture will deter extrusion of the mandibular incisors. Since the large interocclusal distance developed with the malocclusion is used to eat, breathe, and speak and since a prosthesis does not treat the basic malocclusion, any increase in the vertical dimension of occlusion should be minimized. Type IV traumatic ouerlap. The fourth type of traumatic roverlap is characterized by the movement or extrusion of the mandibular teeth into the abraded lingual surface of the maxillary teeth (Fig. 4). This is the most confusing of the four types of as a result of changes in the posterior occlusion, traumatic overlap. It usually ckvelops rather than from the deterioration of an abnormality in growth and development. Abrasion, erosion, and loss of vertical dimension of occlusion are characteristic of this type of traumatic overlap (Fig. 9A).
34
J. Prosthet.
Akerly
Dent.
July, 1977
There may be a loss of occlusal vertical dimension as a result of wear, erosion, or loss of teeth if there is no compensatory eruption. The goal of treatment is to restore lost vertical dimension of occlusion. In restoring the mandible to the proper vertical dimension in centric relation, the excessive overlap problem is usually eliminated (Figs. 9B and 9C). The restoration of occlusal vertical dimension and the elimination of deflective occlusal contacts are the keys to treating the fourth type of traumatic overlap problem.
SUMMARY AND CONCLUSIONS It is helpful to categorize patients with traumatic overlap of the anterior teeth into four types. The numerous etiologic factors must be analyzed to arrive at a logical treatment plan and a definitive prognosis. 1. The tendency for extrusion is common to all types of traumatic overlap. 2. Psychological problems as a result of esthetic and phonetic dissatisfaction are most characteristic of the Type I traumatic overlap problem. 3. The traumatic forces from the overlap relationships of Types I and II may accelerate the progress of periodontitis. 4. An increase in the vertical dimension of occlusion, solely for the purpose of accommodating a prosthesis, should be limited to the third type of traumatic overlap. 5. If the vertical dimension of occlusion must be increased, the increase should not exceed that necessary to accommodate a prosthesis. Prosthodontic treatment does not treat the basic malocclusion of the patient. 6. When diagnostic findings indicate that the vertical dimension of occlusion has decreased, then the vertical dimension of occlusion should be restored prior to or concurrent with the restoration of the anterior teeth. 7. The removal of deflective occlusal contacts and the restoration of occlusion in centric relation should be routine treatment for patients with traumatic overlap of the anterior teeth. 8. Prosthodontic restorations should be designed to deter extrusion and movement of the teeth- and also restore function in a definitive manner.
References 1. 2. 3. 4. 5. 6. 7.
Boucher, Mosby Sicher, Company, Sicher, Sicher, Ramfjord, Company, Boucher, Mosby Goodkind,
C. 0.: Current Clinical Company, p. 282. H., and DuBrul, E. L.: p. 262. H.: Oral Anatomy, ed. H.: Oral Anatomy, ed. S. P., and Ash, M. p. 2 11. C. 0.: Current Clinical Company, p. 415. R. J.: Mandibular
PROSTHET. DENT. 18: 438-447, 12814 KINGS FORREST SAN ANTONIO, TEXAS 78230
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Terminology, With
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the
The
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The
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1974,
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