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Permanent retention with a nonparallel pin retainer
Permanent retention with a nonparallel pin retainer George
Andreasen,
Wallace Iowa City,
W.
D.D.S.,
Johnson,
M.S.D.,*
D.D.S.,
and
MS.**
Iowa
R
etention in orthodontics is a continued problem. In the majority of patients, retainers are left in the mouth for a reasonable period of time and then are removed. No further retention is needed and the dentition remains in a state of dynamic stability, but in a different tooth relationship from where it was when the bands were removed. Still there is a small percentage of cases in which spaces continue to open between central incisors after the retainers are removed, even though the retention is continued for an extensive period of time. In other words, no matter what the clinician does in terms of removable retention, the space between central incisors recurs. To some patients this diastema makes little or no difference, and to others it means that the orthodontist has fallen short of expectations. Therefore, it is the purpose of this article to describe a method of permanent retention for those cases in which this approach is warranted. Review
of
the
literature
Good reasons are given for the return of orthodontically treated teeth to positions other than those of the finished case. One of the most basic reasons is the genetically determined morphologic pattern.l Put another way, posttreatment change has been termed “the physiologic basis of relapse.“2 Support for this concept of the return of teeth after orthodontic correction to a fundamentally inherited a.rch shape is given by several other orthodontists.3-6 In view of the known inherited pattern, the positive approach is to treat to the known pattern by shaping arch wires throughout treatment to conform to the original arch pattern. *Chairman, Department Iowa. ““Chairman, Department versity of Iowa.
of
Orthodontics, of
Operative
College Dentistry,
of
Dentistry,
College
State of
Dentistry,
University State
of Uni-
Volume Number
57 4
Permanent
retention
with nonparallel
pin retainer
401
Posttreatment return may also be caused by the unbalanced forces remaining in the connective tissue fibers after tooth movement. The transseptal fibers have been shown to have tension in them 232 days after orthodontic tooth movement.7 It is reasonable, therefore, to retain rotations for a minimum period of a year. Canine-to-canine mandibular lingual arches are sometimes left in the mouth until the third molars erupt to minimize mandibular anterior crowding. Tweeds has clinically demonstrated that, according to more facially horizontal growth patterns with crowded arches or bimaxillary protrusions, one has more stability in the dentition if he extracts teeth. Strang supports him in his extraction concepts but goes further and says that the canines should be used as a guide for predicting arch stability. In other words, the more the canines have been expanded, the more probable it is that they will return at least some distance toward the midline after removal of retention.9 A rationale for maintaining teeth in a balanced position and upright over “basal” bone is given by many. This is an excellent generalized concept, but it is difficult to judge clinically exactly where the “balanced position” is located. One possibility is to remove arch wires and observe the changes of tooth position to equilibrium while the bands are still cemented on the teeth. RiedellO has thoroughly reviewed the problem and divided retention requirements into three groups: (1) cases requiring no retention, (2) cases in which it is necessary to continue permanent or semipermanent retention, and (3) cases requiring varying lengths of retention. Among the second group are those “cases which initially had considerable spacing.” Muscle balance and the objectives for maintaining the dentition with appliances in the balanced state are discussed by Graber.ll Suggested devices to allow as much functional tooth repositioning as possible are the tooth positioner, the retention plate, variations of the Hawley retainer, and lingual arches. Englert? suggests no retention at all. Concerning the removal of retainers, Renfroe13 suggests that this be done at varying lengths of time, depending on the original circumstances of the diagnosis. Although one is limited in his treatment to a degree, there are specific caSes that can be treated and held stable by permanent retention.14 The case of a large amount of anterior spacing is one, and the case of a large diastema in an adult, caused by a fibrous labial frenum,15 is another. In the cases of large amounts of anterior spacing, permanent staples I6 have been used to keep spaces closed permanently. Septotomies and frenectomies have been recommended in cases where a fibrous labial frenum is the cause of the &sterna. Whatever the cause for the return, the only way to understand the problem more completely is to take follow-up records and observe the changing position of the teeth. Case
report
of
missing
lateral
incisors
A specific reported case needing permanent retention is that of an adult Class II dentition with 8 mm. of generalized spacing in the maxillary anterior segment and 6 mm. of spacing in the mandibular anterior segment. The patient is in good health. Intradral roentgenograms show a normal bone, periodontal membrane, and soft-tissue relationship. There are only four restorations in the
402
Andreasen
and Johnson
C Fig. 1. A, Class II dental relationships lateral incisors and 8 mm. of anterior “normal” skeletal and Class II dental “Normal” profile photograph.
Amer.
D found in the adult maxillary spacing. relationships. D,
J. Orthodont. April 1970
E dentition. B, Congenitally missing C, Cephalometric film revealing “Normal” frontal photograph. E,
dentition, and they are located in three permanent first molars. Cephalometric films reveal a “normal” skeletal and a Class II molar relation. The facial photographs show “normal” frontal and profile facial features (Fig. 1). The diagnosis is congenital absence of lateral incisors, generalized spacing of the maxillary and mandibular anterior segments, Class II dental relations, normal skeletal pattern, and normal facial profile. The treatment plan was to condense all spaces in the maxillary and mandibuular anterior segments, torque the maxillary anterior roots lingually, leave the molars in a Class II relationship, and use the maxillary canines in place of the missing lateral incisors. No extractions were recommended in this treatment plan, and the objectives of the treatment plan were accomplished. The original condition of a lack of lateral incisors and a large amount of anterior spacing is shown before and after space closure ; however, 3 days after
Volume Number
57 4
Fig. 2. A, Anterior and bite opening. closed again with
Permanent
spacing C, Space immediate
retention
before space closure. beginning to open seating of a Hawley
with nonparallel
6, Anterior spacing in 3 days after band retainer.
pin retainer
403
after space closure removal. D, Spaces
bands were removed and molar-to-molar elastics were being worn, a space began bow retainer with spurs was seated in the mouth the next day to hold the space to open between the central incisors. The space was again condensed and a labialshut (Fig. 2). Prognosis was guarded as it now seemed apparent that the spaces would not remain closed after removal of the retaining appliance. Only by means of some form of permanent retention could the maxillary anterior segment from canine to canine be held in the desired closed position. Since patient motivation, caries index, and occlusal conditions were ideal, a combined approach of orthodontic therapy and operative dentistry was formulated for the design, fabrication, and placement of the permanent retainer. The anterior teeth were in excellent condition. There were no carious lesions or restorations. Because of the low caries index and the patient’s excellent hygiene habits, it was thought that there could be a minimal reduction of tooth structure to accomplish the appliance. Obviously, the connecting bars between the teeth should not serve as food traps that would not be self-cleaning or would be difficult to clean. Indeed, for the longevity of this appliance, it would be most necessary for it to be designed to be as self-cleansing as possible. The tooth attachments for the appliance were designed as intracoronal restorations, occupying the gingival half of the lingual surface of each tooth. They were to be sealed in place by zinc oxyphosphate cement and held securely in place by self-threading pins. The use of threaded pins was also necessitated by the lack
404
Andreasen
and Johnson
Amer.
TOTAL
GINGIVAL
fig.
3. Design
of
the
SELF
TISSUE
CLEANSING
J. Orthodont. April 1970
MARGINS
COVERING
GINGIVAL
MARGINS permanent retainer.
Fig. 4. A, Design of each inlay. 0.024 inch plastic pins inserted porary cement in place, ending
B, Cavity preparations into prepared holes the first appointment.
and and
the
0.024 inch impression
holes for taking.
pins. C, D, Tem-
of parallelism of the four lingual surfaces. The bars connecting the restorations curved lingually and lay close to the gingival or palatal tissue. The design of the retainer is seen in Fig. 3. Permanent
retention
with
a nonparallel
pin
ftxed
retainer
Prepara%n of teeth. Inlays as shown on the waxed model were designed for the lingual surface of each tooth. Corresponding preparations were made in the mouth. Next, 0.024 inch holes were drilled in the corners of each prepara-
Volume Number
Fig.
57 4
5.
Laboratory
replaced C,
Holes
E, 0.032 into
Permanent
place.
with
fabrication 0.024
in
appliance
inch
nickel G,
Pins
inch
of
cut
to
the
nickel
redrilled silver
retainer
silver to
0.032
self-threading surface
retention
of
pin
with nonparallel
and ready
inch.
D,
tapered appliance.
the
second
for
the
Trial pins.
H,
Final
appointment.
wax-up.
seating
A,
B, Casting of
F, Appliance high
pin retainer
polish
appliance and
pins
on
retainer.
405
Plastic of
in the being
pins
retainer. mouth. screwed
tion, great care being taken to avoid the pulp. Plastic pins (0.024 inch) were inserted into the prepared holes, and an impression was made of the preparations with the plastic pins in place. Temporary cement was then placed in the cavity preparations and the patient was dismissed with instructions to wear the labial-bow removable retainer at all times until the next appointment (Fig. 4). Laboratory fabrication of retainer. The impression was poured in dyestone.
406
Andreasen
and Johnson
Amer.
J. Orthodont. April 1970
The plastic pins which remained in the stone model upon removal from the impression were gently removed and replaced in the stone model by means of tapered 0.024 inch nickel silver pins. The inlays and attachments were waxed and cast in one piece. In this case, the nickel silver pins had to be removed before casting because of the fragility of the wax patterns. After casting, the appliance was cleaned and semipolished. The holes in the appliance were redrilled with a 0.032 inch drill. The appliance was now ready to finish in the mouth. Seat&g the retainer. The temporary cement was removed, and the preparations were cleaned. The 0.024 inch holes in the teeth were redrilled with a 0.027 inch bur. The appliance was trial seated, burnished, and finished as deemed necessary. It was then permanently seated with zinc oxyphosphate cement and secured in place by means of 0.032 inch nickel silver self-threading tapered pins screwed through each pinhole in the appliance and into the tooth. The pins were cut and ground smooth with the surface of the appliance and the entire retainer was given a final high polish (Fig. 5). Conclusion
As we become more specialized in the many areas of dentistry, it becomes apparent that consultation, communication, and teamwork with other colleagues in our profession are necessary for better service to our patients. When this approach is taken, the concept of total patient care becomes a reality. REFERENCES
1. Goldstein, A.: The dominance of the morphological pattern, implication for treatment, Angle Orthodontist 23: 187, 1953. 2. Huckaba, G. W.: Physiologic basis of relapse, AM. J. ORTHODONTICS 38: 335, 1952. 3. Hellman, M.: Orthodontic results many years after treatment, Aa6. J. ORTHODONTICS & ORAL SURG.~~: 843,194O. 4. Waldron, R.: Reviewing the problem of retention, AM. J. ORTHOD~NIWS & ORAL SURG. 28: 770, 1942. 5. Grieve, G. W.: The stability of the treated denture, AM. J. ORTHODONTICS & ORAL SURG. 30: 171, 1944. 6. Chapman, H., and Russell, M. L.: Failures in orthodontic practice, D. Record 58: 57, 1938. 7. Reitan, K.: Tissue rearrangement during retention of orthodontically rotated teeth, Angle Orthodontist 19: 105, 1959. 8. Tweed, C. H.: Indications for the extraction of teeth in orthodontic procedures, Abr. J. ORTHODONTICS&ORAL SURG. 30: 405,1944. 9. Fischer, B.: Retention: A discussion of permanency of results in orthodontic practice, AM.J.ORTHODONTICS & ORAL SURG.~~: 5,1943. 10. Riedel, R. A.: A review of the retention problem, Angle Orthodontist 36: 179, 1960. 11. Graber, T. H.: Orthodontics, Philadelphia, 1961, W. B. Saunders Company, p. 496. 12. Englert, G. L.: A clinical ideology and observations on unretained orthodontic corrections, Angle Orthodontist 25: 85, 1955. 13. Renfroe, E. W.: Technique training in orthodontics, Ann Arbor, Mich., 1960, Edwards Brothers, Inc., pp. 207, 220. 14. Skogsborg, C.: The permanent retention of teeth after orthodontic treatment, Dental Cosmos 69: 1117, 1927. 15. Angle, E. H.: Treatment of malocclusion of the teeth, Philadelphia, 1907, S. S. White Dental Mfg. Co., p. 569. 16. Case, C. S.: Dental orthopedia, New York, 1921, reprinted by L. L. Bruder, 1963, p. 401.
Andreasen,
Wallace Iowa City,
W.
D.D.S.,
Johnson,
M.S.D.,*
D.D.S.,
and
MS.**
Iowa
R
etention in orthodontics is a continued problem. In the majority of patients, retainers are left in the mouth for a reasonable period of time and then are removed. No further retention is needed and the dentition remains in a state of dynamic stability, but in a different tooth relationship from where it was when the bands were removed. Still there is a small percentage of cases in which spaces continue to open between central incisors after the retainers are removed, even though the retention is continued for an extensive period of time. In other words, no matter what the clinician does in terms of removable retention, the space between central incisors recurs. To some patients this diastema makes little or no difference, and to others it means that the orthodontist has fallen short of expectations. Therefore, it is the purpose of this article to describe a method of permanent retention for those cases in which this approach is warranted. Review
of
the
literature
Good reasons are given for the return of orthodontically treated teeth to positions other than those of the finished case. One of the most basic reasons is the genetically determined morphologic pattern.l Put another way, posttreatment change has been termed “the physiologic basis of relapse.“2 Support for this concept of the return of teeth after orthodontic correction to a fundamentally inherited a.rch shape is given by several other orthodontists.3-6 In view of the known inherited pattern, the positive approach is to treat to the known pattern by shaping arch wires throughout treatment to conform to the original arch pattern. *Chairman, Department Iowa. ““Chairman, Department versity of Iowa.
of
Orthodontics, of
Operative
College Dentistry,
of
Dentistry,
College
State of
Dentistry,
University State
of Uni-
Volume Number
57 4
Permanent
retention
with nonparallel
pin retainer
401
Posttreatment return may also be caused by the unbalanced forces remaining in the connective tissue fibers after tooth movement. The transseptal fibers have been shown to have tension in them 232 days after orthodontic tooth movement.7 It is reasonable, therefore, to retain rotations for a minimum period of a year. Canine-to-canine mandibular lingual arches are sometimes left in the mouth until the third molars erupt to minimize mandibular anterior crowding. Tweeds has clinically demonstrated that, according to more facially horizontal growth patterns with crowded arches or bimaxillary protrusions, one has more stability in the dentition if he extracts teeth. Strang supports him in his extraction concepts but goes further and says that the canines should be used as a guide for predicting arch stability. In other words, the more the canines have been expanded, the more probable it is that they will return at least some distance toward the midline after removal of retention.9 A rationale for maintaining teeth in a balanced position and upright over “basal” bone is given by many. This is an excellent generalized concept, but it is difficult to judge clinically exactly where the “balanced position” is located. One possibility is to remove arch wires and observe the changes of tooth position to equilibrium while the bands are still cemented on the teeth. RiedellO has thoroughly reviewed the problem and divided retention requirements into three groups: (1) cases requiring no retention, (2) cases in which it is necessary to continue permanent or semipermanent retention, and (3) cases requiring varying lengths of retention. Among the second group are those “cases which initially had considerable spacing.” Muscle balance and the objectives for maintaining the dentition with appliances in the balanced state are discussed by Graber.ll Suggested devices to allow as much functional tooth repositioning as possible are the tooth positioner, the retention plate, variations of the Hawley retainer, and lingual arches. Englert? suggests no retention at all. Concerning the removal of retainers, Renfroe13 suggests that this be done at varying lengths of time, depending on the original circumstances of the diagnosis. Although one is limited in his treatment to a degree, there are specific caSes that can be treated and held stable by permanent retention.14 The case of a large amount of anterior spacing is one, and the case of a large diastema in an adult, caused by a fibrous labial frenum,15 is another. In the cases of large amounts of anterior spacing, permanent staples I6 have been used to keep spaces closed permanently. Septotomies and frenectomies have been recommended in cases where a fibrous labial frenum is the cause of the &sterna. Whatever the cause for the return, the only way to understand the problem more completely is to take follow-up records and observe the changing position of the teeth. Case
report
of
missing
lateral
incisors
A specific reported case needing permanent retention is that of an adult Class II dentition with 8 mm. of generalized spacing in the maxillary anterior segment and 6 mm. of spacing in the mandibular anterior segment. The patient is in good health. Intradral roentgenograms show a normal bone, periodontal membrane, and soft-tissue relationship. There are only four restorations in the
402
Andreasen
and Johnson
C Fig. 1. A, Class II dental relationships lateral incisors and 8 mm. of anterior “normal” skeletal and Class II dental “Normal” profile photograph.
Amer.
D found in the adult maxillary spacing. relationships. D,
J. Orthodont. April 1970
E dentition. B, Congenitally missing C, Cephalometric film revealing “Normal” frontal photograph. E,
dentition, and they are located in three permanent first molars. Cephalometric films reveal a “normal” skeletal and a Class II molar relation. The facial photographs show “normal” frontal and profile facial features (Fig. 1). The diagnosis is congenital absence of lateral incisors, generalized spacing of the maxillary and mandibular anterior segments, Class II dental relations, normal skeletal pattern, and normal facial profile. The treatment plan was to condense all spaces in the maxillary and mandibuular anterior segments, torque the maxillary anterior roots lingually, leave the molars in a Class II relationship, and use the maxillary canines in place of the missing lateral incisors. No extractions were recommended in this treatment plan, and the objectives of the treatment plan were accomplished. The original condition of a lack of lateral incisors and a large amount of anterior spacing is shown before and after space closure ; however, 3 days after
Volume Number
57 4
Fig. 2. A, Anterior and bite opening. closed again with
Permanent
spacing C, Space immediate
retention
before space closure. beginning to open seating of a Hawley
with nonparallel
6, Anterior spacing in 3 days after band retainer.
pin retainer
403
after space closure removal. D, Spaces
bands were removed and molar-to-molar elastics were being worn, a space began bow retainer with spurs was seated in the mouth the next day to hold the space to open between the central incisors. The space was again condensed and a labialshut (Fig. 2). Prognosis was guarded as it now seemed apparent that the spaces would not remain closed after removal of the retaining appliance. Only by means of some form of permanent retention could the maxillary anterior segment from canine to canine be held in the desired closed position. Since patient motivation, caries index, and occlusal conditions were ideal, a combined approach of orthodontic therapy and operative dentistry was formulated for the design, fabrication, and placement of the permanent retainer. The anterior teeth were in excellent condition. There were no carious lesions or restorations. Because of the low caries index and the patient’s excellent hygiene habits, it was thought that there could be a minimal reduction of tooth structure to accomplish the appliance. Obviously, the connecting bars between the teeth should not serve as food traps that would not be self-cleaning or would be difficult to clean. Indeed, for the longevity of this appliance, it would be most necessary for it to be designed to be as self-cleansing as possible. The tooth attachments for the appliance were designed as intracoronal restorations, occupying the gingival half of the lingual surface of each tooth. They were to be sealed in place by zinc oxyphosphate cement and held securely in place by self-threading pins. The use of threaded pins was also necessitated by the lack
404
Andreasen
and Johnson
Amer.
TOTAL
GINGIVAL
fig.
3. Design
of
the
SELF
TISSUE
CLEANSING
J. Orthodont. April 1970
MARGINS
COVERING
GINGIVAL
MARGINS permanent retainer.
Fig. 4. A, Design of each inlay. 0.024 inch plastic pins inserted porary cement in place, ending
B, Cavity preparations into prepared holes the first appointment.
and and
the
0.024 inch impression
holes for taking.
pins. C, D, Tem-
of parallelism of the four lingual surfaces. The bars connecting the restorations curved lingually and lay close to the gingival or palatal tissue. The design of the retainer is seen in Fig. 3. Permanent
retention
with
a nonparallel
pin
ftxed
retainer
Prepara%n of teeth. Inlays as shown on the waxed model were designed for the lingual surface of each tooth. Corresponding preparations were made in the mouth. Next, 0.024 inch holes were drilled in the corners of each prepara-
Volume Number
Fig.
57 4
5.
Laboratory
replaced C,
Holes
E, 0.032 into
Permanent
place.
with
fabrication 0.024
in
appliance
inch
nickel G,
Pins
inch
of
cut
to
the
nickel
redrilled silver
retainer
silver to
0.032
self-threading surface
retention
of
pin
with nonparallel
and ready
inch.
D,
tapered appliance.
the
second
for
the
Trial pins.
H,
Final
appointment.
wax-up.
seating
A,
B, Casting of
F, Appliance high
pin retainer
polish
appliance and
pins
on
retainer.
405
Plastic of
in the being
pins
retainer. mouth. screwed
tion, great care being taken to avoid the pulp. Plastic pins (0.024 inch) were inserted into the prepared holes, and an impression was made of the preparations with the plastic pins in place. Temporary cement was then placed in the cavity preparations and the patient was dismissed with instructions to wear the labial-bow removable retainer at all times until the next appointment (Fig. 4). Laboratory fabrication of retainer. The impression was poured in dyestone.
406
Andreasen
and Johnson
Amer.
J. Orthodont. April 1970
The plastic pins which remained in the stone model upon removal from the impression were gently removed and replaced in the stone model by means of tapered 0.024 inch nickel silver pins. The inlays and attachments were waxed and cast in one piece. In this case, the nickel silver pins had to be removed before casting because of the fragility of the wax patterns. After casting, the appliance was cleaned and semipolished. The holes in the appliance were redrilled with a 0.032 inch drill. The appliance was now ready to finish in the mouth. Seat&g the retainer. The temporary cement was removed, and the preparations were cleaned. The 0.024 inch holes in the teeth were redrilled with a 0.027 inch bur. The appliance was trial seated, burnished, and finished as deemed necessary. It was then permanently seated with zinc oxyphosphate cement and secured in place by means of 0.032 inch nickel silver self-threading tapered pins screwed through each pinhole in the appliance and into the tooth. The pins were cut and ground smooth with the surface of the appliance and the entire retainer was given a final high polish (Fig. 5). Conclusion
As we become more specialized in the many areas of dentistry, it becomes apparent that consultation, communication, and teamwork with other colleagues in our profession are necessary for better service to our patients. When this approach is taken, the concept of total patient care becomes a reality. REFERENCES
1. Goldstein, A.: The dominance of the morphological pattern, implication for treatment, Angle Orthodontist 23: 187, 1953. 2. Huckaba, G. W.: Physiologic basis of relapse, AM. J. ORTHODONTICS 38: 335, 1952. 3. Hellman, M.: Orthodontic results many years after treatment, Aa6. J. ORTHODONTICS & ORAL SURG.~~: 843,194O. 4. Waldron, R.: Reviewing the problem of retention, AM. J. ORTHOD~NIWS & ORAL SURG. 28: 770, 1942. 5. Grieve, G. W.: The stability of the treated denture, AM. J. ORTHODONTICS & ORAL SURG. 30: 171, 1944. 6. Chapman, H., and Russell, M. L.: Failures in orthodontic practice, D. Record 58: 57, 1938. 7. Reitan, K.: Tissue rearrangement during retention of orthodontically rotated teeth, Angle Orthodontist 19: 105, 1959. 8. Tweed, C. H.: Indications for the extraction of teeth in orthodontic procedures, Abr. J. ORTHODONTICS&ORAL SURG. 30: 405,1944. 9. Fischer, B.: Retention: A discussion of permanency of results in orthodontic practice, AM.J.ORTHODONTICS & ORAL SURG.~~: 5,1943. 10. Riedel, R. A.: A review of the retention problem, Angle Orthodontist 36: 179, 1960. 11. Graber, T. H.: Orthodontics, Philadelphia, 1961, W. B. Saunders Company, p. 496. 12. Englert, G. L.: A clinical ideology and observations on unretained orthodontic corrections, Angle Orthodontist 25: 85, 1955. 13. Renfroe, E. W.: Technique training in orthodontics, Ann Arbor, Mich., 1960, Edwards Brothers, Inc., pp. 207, 220. 14. Skogsborg, C.: The permanent retention of teeth after orthodontic treatment, Dental Cosmos 69: 1117, 1927. 15. Angle, E. H.: Treatment of malocclusion of the teeth, Philadelphia, 1907, S. S. White Dental Mfg. Co., p. 569. 16. Case, C. S.: Dental orthopedia, New York, 1921, reprinted by L. L. Bruder, 1963, p. 401.