BOND
STRENGTH
OF REPAIRED
AMALGAM
3. Brown KB, Molvar MP, Demarest VA, Hasegawa TK, Heinecke PN. Flexural strength of repaired high-copper amalgam. Oper Dent 1986; 11:131-5. 4. Berge M. Flexural strength of joined and intact amalgam. Acta Odontal Stand 1982;40:313-7. 5. Gordon M, Ben-Amar A, Librus S, Liberman R. Bond strength of mechanically condensed repaired high-copper amalgam. Quintessence Int 1987;18:471-4. 6. Scott GL, Grisius RJ. Bond strength at the interface of new and old spherical amalgam. US Navy Med News Lett 1969;54:34. 7. Jorgensen KD, Saito T. Bond strength of repaired amalgam. Acta Odontal Stand 1968;26:605-15. 8. Kirk EEJ. Amalgam to amalgam bond: a preliminary report. Dent Practioner 1962;12:371-2. 9. Consani S, Ruhnke LA, Stolf WL. Infiltration of a radioactive solution into jointed silver-amalgam. J PROSTHET DENT 1977;37:158-63. 10. Cowan RD. Amalgam repair-a clinical technique. J PROSTHET DENT 1983;49:49-51. 11. Rodriguez MS, Dickson G. Some tensile properties
of amalgam. J Dent
Res 1962;41:840-52.
Tooth contacts morphology Bengt
Ingervall,
Bruno
Stettler,
University
of Bern,
in eccentric DDS,
Odont
DDS, Bern,
Dr
Med
Dr,8
Daniel
12. Jorgensen KD. Amalgame in der Zahnheilkunde. Munchen-Wien: Hanser-Verlag, 1977. 13. Mahler DB. An analysis of stresses in a dental amalgam restoration. J Dent Res 1958;37:516-26. 14. Asgar K, Sutfin L. Brittle fracture of dental amalgam. J Dent Res 1965;44:977-88. 15. Jorgensen KD. Recent developments in alloys for dental amalgams: their properties and proper use. Int Dent J 1976;26:369-77. 16. Vrijhoef MMA, Vermeersch AG, Spanauf AJ. Diametral tensile strength of twenty-three hardened commercial amalgams. J Oral Rehabil 1979;6:153-7. 17. Asgar K, Arfaei AH, Mahler DB. Evaluation of amalgam tensile test methods [Abstract]. J Dent Res 1977;56:77. Reprint
requests to:
DR. FARHAD HADAVI COLLEGE OF DENTISTRY UNIVERSITY OF SASKATCHEWAN SASKATOON S7N OWO CANADA
mandibular Meyer,
DDS,
positions Dr
Med
Dent,b
and facial
and
Dentb
Switzerland
Correlations between facial morphology and tooth contacts in excursive mandibular positions were studied in ‘75 men aged 20 to 33 years. The morphology of the dentition was verified on dental casts and the face was measured by use of roentgen cephalometry. No correlation was observed between facial morphology and the number of tooth contacts in the retruded position; however, wide dental arches and jaws displayed many contacts on protrusion. Numerous contacts on the functional side in group function were noted in individuals with a facial morphology associated with distal occlusion, such as Angle class II, division 1. Wide dental arches were associated with multiple functional-side contacts whereas tooth contacts on the nonfunctional side were related to the inclination of the mandible. A “long-face” morphology was related to contacts on the nonfunctional side. There was a negative correlation between the extent of the overbite (vertical overlap) and the number of tooth contacts on the nonfunctional side. (J PROSTHET DENT 1992;07:317-22.)
D
uring lateral excursions of the mandible or laterotrusion, two types of tooth contact are evident on the functional or working side: group function and canine protection. Group function is defined as contacts between two or more pairs of opposing teeth on the working side,le3 whereas a canine-protected occlusion implies contact only between the canines on the working side.*T5 During laterotrusion, some individuals have contacts between opposing aProfessor and Chairman, bPrivate practice. 1011132710
THE
JOURNAL
Department
OF PROSTHETIC
of Orthodontics.
DENTISTRY
teeth on the nonfunctional or balancing side. However, the tooth contacts during retrusion and protrusion of the mandible vary widely between young adults.6 Information is sparse on associations between patterns of tooth contact and facial morphology. Madone and Ingerval17 reported a negative correlation between group function and the width of the maxillary dental arch but a positive correlation with the sagittal jaw relation in young adults after orthodontic treatment. Canine protection was positively correlated with the width of the maxillae and molar relation but negatively with the sagittal jaw relation and with the inclination of the mandibular incisors. Group
317
INGERVALL,
Fig.
AND
STETTLER
1. Measurement of molar relation.
function tends to occur predominately in patients with narrow maxillae and a large sagittal jaw relation, whereas canine protection is predominant in individuals with wide maxillae and a mandible that developed in an anterior direction. Conversely, DiPietros discoveredthat tooth contacts on the functional side were related to the inclination of the mandible. In a study of young adults, he reported an association betweenthe Frankfort-mandibular plane angleand working-side tooth contacts. Canineprotection occurred in individuals with a low Frankfort-mandibular plane angle, but group function wasidentified with a high angle. There are no reported studiesdescribingthe relationship betweennoninterfering (normal) contacts on the nonworking side and facial morphology. However, investigations of nonworking-side interferences or contacts on the nonfunctional side precluding contacts on the functional side are available. In these studies,interfering contacts were prevalent in individuals with an anterior open bite and with crossbitesor distal occlusion.g-13 During orthodontic treatment, occlusionsare developed with variable patterns of tooth contact on mandibular laterotrusion. Therefore, it would be helpful to know the type of contact pattern that is normal for personswith a specific facial morphology. The information is critical in predicting the development of unfavorable tooth contacts or occlusal interferences. In a previous investigation, tooth contacts in static excursive mandibular positions in young adults were studied. The morphology of the dentitions and the faceswere alsorecorded, and this study documented the associations between facial shape and excursive tooth contacts. METHOD The subjects selected for this study were 75 males, mostly dental students, included in the previous investigation by Ingervall et al6 Their agesvaried between 20 and 33 years, with a median ageof 24 years. The subjectshad 318
MEYER,
Fig. 2. Reference points for analysis of profile cephalogram.
well-preserved dentitions with minimal teeth missing or sparserestorations, and they were selectedrandomly irrespective of the type of occlusion. Normal occlusionsand various types of malocclusionswith diverse facial morphology were identified. Approximately half of the men had been treated orthodontically by a variety of methods, including the removal of permanent teeth in 18of the subjects. The number of opposingtooth contacts wasdetermined by use of alginate irreversible hydrocolloid indices. The contacts were recorded in the retruded mandibular position, two protruded positions,and in two laterotrusive positions with indices recorded on the working and the nonworking sides. The number of tooth contacts in the retruded position varied between 1 and 10, with a median of 3. On 1.5 mm protrusion of the mandible from the intercuspal position and on protrusion to the edge-to-edgeposition of the incisors,the median tooth contacts were 3, with a range of 1 through 7. In the two protrusive positions, most subjects had contacts on the incisorsonly; namely, 66% in 1.5 mm protrusion and in 73% in edge-to-edgeposition, whereas contacts on the premolarsand molarsexclusively wererare. Static laterotrusive tooth contacts were studied 1.5 mm and 3 mm from the centered mandibular midline position. For both positions,the mediannumber of tooth contacts on the functional side was 2, with a range 0 through 6 on 1.5 mm laterotrusion and 0 through 8 on 3 mm laterotrusion. Group function on the functional side or more than one opposingtooth contact wasevident in approximately 70% and 60% of the subjectsor11.5 mm and 3 mm laterotrusion, respectively. In the remaining 30% and 40% of the subjects, canine-protected occlusionwas observed.
MARCH
1992
VOLUME
67
NUMBER
3
TOOTH
CONTACTS
AND
FACIAL
MORPHOLOGY
ILi Fig. 3. Reference lines for analysis of profile cephalogram.
On the nonfunctional side, tooth contacts varied from 0 to 2 on 1.5 mm laterotrusion and from 0 to 3 on 3 mm laterotrusion. The median values were 1 and 0 on 1.5 mm and 3 mm laterotrusion. Tooth contact on the nonfunctional side combined with contact on the functional side, or balanced occlusion, was discovered in approximately half of the subjects on 1.5 mm laterotrusion and in approximately a third on 3 mm laterotrusion. A nonfunctional side interference or tooth contact only on the nonfunctional side was rare. The details of the dentitions and the patterns of tooth contacts were documented in Ingervall et a1.6
Analysis
of dental
casts
Dental stone casts were made from irreversible hydrocolloid impressions. The width of the dental arches between the canines and the first molars was measured with sliding calipers and read to the nearest 0.1 mm. The reference points for maxillary molars were the central fossae. The mandibular molars were measured at the tips of the distobuccal cusps and the incisal tips were recorded for the canines. When the cusp tip was abraded, the approximate center of the abraded surface was designated. The vertical and horizontal overlaps including the mesiodistal relations of the first molars were measured with the casts secured in the intercuspal position. Vertical and horizontal overlap were measured to the nearest 0.5 mm on both central incisors by use of the method of Lundstroem,14 The mesiodistal molar relation was determined by superimposing the mesial surface of one molar on the other, and the distance between the maxillary and mandibular mesial surfaces was measured to the nearest 0.1 mm with sliding calipers (Fig. 1).
THE
JOURNAL
OF PROSTHETIC
DENTISTRY
Fig. 4. Reference points for analysis of frontal cephalogram.
Radiographic
cephalometry
Profile and frontal or posteroanterior cephalograms were obtained with the mandible at the intercuspal position with the Frankfort plane horizontal. In the profile cephalogram, the linear enlargement was 3.3% and in the frontal cephalogram 5% for structures in the frontal plane through the porion. The reference points and lines used in the analysis of the profile cephalogram are shown in Figs. 2 and 3, and the reference points in the analysis of the frontal cephalogram in Fig. 4.
RESULTS The results of the analysis of the dental casts (Table I) and those of the cephalometric analysis (Table II) revealed a wide variation in the morphology of both the dentition and the face.
Correlation between number contacts and facial morphology
of tooth
The relationship between the tooth contacts in the different mandibular positions and the morphologic variables was computed by use of a Spearman rank correlation.
Retruded
position
The tooth contacts in the retruded position were significantly correlated with two morphologic variables, the mesiodistal molar relation on the left side (rho -0.23, 0.01
STRENGTH
OF REPAIRED
AMALGAM
3. Brown KB, Molvar MP, Demarest VA, Hasegawa TK, Heinecke PN. Flexural strength of repaired high-copper amalgam. Oper Dent 1986; 11:131-5. 4. Berge M. Flexural strength of joined and intact amalgam. Acta Odontal Stand 1982;40:313-7. 5. Gordon M, Ben-Amar A, Librus S, Liberman R. Bond strength of mechanically condensed repaired high-copper amalgam. Quintessence Int 1987;18:471-4. 6. Scott GL, Grisius RJ. Bond strength at the interface of new and old spherical amalgam. US Navy Med News Lett 1969;54:34. 7. Jorgensen KD, Saito T. Bond strength of repaired amalgam. Acta Odontal Stand 1968;26:605-15. 8. Kirk EEJ. Amalgam to amalgam bond: a preliminary report. Dent Practioner 1962;12:371-2. 9. Consani S, Ruhnke LA, Stolf WL. Infiltration of a radioactive solution into jointed silver-amalgam. J PROSTHET DENT 1977;37:158-63. 10. Cowan RD. Amalgam repair-a clinical technique. J PROSTHET DENT 1983;49:49-51. 11. Rodriguez MS, Dickson G. Some tensile properties
of amalgam. J Dent
Res 1962;41:840-52.
Tooth contacts morphology Bengt
Ingervall,
Bruno
Stettler,
University
of Bern,
in eccentric DDS,
Odont
DDS, Bern,
Dr
Med
Dr,8
Daniel
12. Jorgensen KD. Amalgame in der Zahnheilkunde. Munchen-Wien: Hanser-Verlag, 1977. 13. Mahler DB. An analysis of stresses in a dental amalgam restoration. J Dent Res 1958;37:516-26. 14. Asgar K, Sutfin L. Brittle fracture of dental amalgam. J Dent Res 1965;44:977-88. 15. Jorgensen KD. Recent developments in alloys for dental amalgams: their properties and proper use. Int Dent J 1976;26:369-77. 16. Vrijhoef MMA, Vermeersch AG, Spanauf AJ. Diametral tensile strength of twenty-three hardened commercial amalgams. J Oral Rehabil 1979;6:153-7. 17. Asgar K, Arfaei AH, Mahler DB. Evaluation of amalgam tensile test methods [Abstract]. J Dent Res 1977;56:77. Reprint
requests to:
DR. FARHAD HADAVI COLLEGE OF DENTISTRY UNIVERSITY OF SASKATCHEWAN SASKATOON S7N OWO CANADA
mandibular Meyer,
DDS,
positions Dr
Med
Dent,b
and facial
and
Dentb
Switzerland
Correlations between facial morphology and tooth contacts in excursive mandibular positions were studied in ‘75 men aged 20 to 33 years. The morphology of the dentition was verified on dental casts and the face was measured by use of roentgen cephalometry. No correlation was observed between facial morphology and the number of tooth contacts in the retruded position; however, wide dental arches and jaws displayed many contacts on protrusion. Numerous contacts on the functional side in group function were noted in individuals with a facial morphology associated with distal occlusion, such as Angle class II, division 1. Wide dental arches were associated with multiple functional-side contacts whereas tooth contacts on the nonfunctional side were related to the inclination of the mandible. A “long-face” morphology was related to contacts on the nonfunctional side. There was a negative correlation between the extent of the overbite (vertical overlap) and the number of tooth contacts on the nonfunctional side. (J PROSTHET DENT 1992;07:317-22.)
D
uring lateral excursions of the mandible or laterotrusion, two types of tooth contact are evident on the functional or working side: group function and canine protection. Group function is defined as contacts between two or more pairs of opposing teeth on the working side,le3 whereas a canine-protected occlusion implies contact only between the canines on the working side.*T5 During laterotrusion, some individuals have contacts between opposing aProfessor and Chairman, bPrivate practice. 1011132710
THE
JOURNAL
Department
OF PROSTHETIC
of Orthodontics.
DENTISTRY
teeth on the nonfunctional or balancing side. However, the tooth contacts during retrusion and protrusion of the mandible vary widely between young adults.6 Information is sparse on associations between patterns of tooth contact and facial morphology. Madone and Ingerval17 reported a negative correlation between group function and the width of the maxillary dental arch but a positive correlation with the sagittal jaw relation in young adults after orthodontic treatment. Canine protection was positively correlated with the width of the maxillae and molar relation but negatively with the sagittal jaw relation and with the inclination of the mandibular incisors. Group
317
INGERVALL,
Fig.
AND
STETTLER
1. Measurement of molar relation.
function tends to occur predominately in patients with narrow maxillae and a large sagittal jaw relation, whereas canine protection is predominant in individuals with wide maxillae and a mandible that developed in an anterior direction. Conversely, DiPietros discoveredthat tooth contacts on the functional side were related to the inclination of the mandible. In a study of young adults, he reported an association betweenthe Frankfort-mandibular plane angleand working-side tooth contacts. Canineprotection occurred in individuals with a low Frankfort-mandibular plane angle, but group function wasidentified with a high angle. There are no reported studiesdescribingthe relationship betweennoninterfering (normal) contacts on the nonworking side and facial morphology. However, investigations of nonworking-side interferences or contacts on the nonfunctional side precluding contacts on the functional side are available. In these studies,interfering contacts were prevalent in individuals with an anterior open bite and with crossbitesor distal occlusion.g-13 During orthodontic treatment, occlusionsare developed with variable patterns of tooth contact on mandibular laterotrusion. Therefore, it would be helpful to know the type of contact pattern that is normal for personswith a specific facial morphology. The information is critical in predicting the development of unfavorable tooth contacts or occlusal interferences. In a previous investigation, tooth contacts in static excursive mandibular positions in young adults were studied. The morphology of the dentitions and the faceswere alsorecorded, and this study documented the associations between facial shape and excursive tooth contacts. METHOD The subjects selected for this study were 75 males, mostly dental students, included in the previous investigation by Ingervall et al6 Their agesvaried between 20 and 33 years, with a median ageof 24 years. The subjectshad 318
MEYER,
Fig. 2. Reference points for analysis of profile cephalogram.
well-preserved dentitions with minimal teeth missing or sparserestorations, and they were selectedrandomly irrespective of the type of occlusion. Normal occlusionsand various types of malocclusionswith diverse facial morphology were identified. Approximately half of the men had been treated orthodontically by a variety of methods, including the removal of permanent teeth in 18of the subjects. The number of opposingtooth contacts wasdetermined by use of alginate irreversible hydrocolloid indices. The contacts were recorded in the retruded mandibular position, two protruded positions,and in two laterotrusive positions with indices recorded on the working and the nonworking sides. The number of tooth contacts in the retruded position varied between 1 and 10, with a median of 3. On 1.5 mm protrusion of the mandible from the intercuspal position and on protrusion to the edge-to-edgeposition of the incisors,the median tooth contacts were 3, with a range of 1 through 7. In the two protrusive positions, most subjects had contacts on the incisorsonly; namely, 66% in 1.5 mm protrusion and in 73% in edge-to-edgeposition, whereas contacts on the premolarsand molarsexclusively wererare. Static laterotrusive tooth contacts were studied 1.5 mm and 3 mm from the centered mandibular midline position. For both positions,the mediannumber of tooth contacts on the functional side was 2, with a range 0 through 6 on 1.5 mm laterotrusion and 0 through 8 on 3 mm laterotrusion. Group function on the functional side or more than one opposingtooth contact wasevident in approximately 70% and 60% of the subjectsor11.5 mm and 3 mm laterotrusion, respectively. In the remaining 30% and 40% of the subjects, canine-protected occlusionwas observed.
MARCH
1992
VOLUME
67
NUMBER
3
TOOTH
CONTACTS
AND
FACIAL
MORPHOLOGY
ILi Fig. 3. Reference lines for analysis of profile cephalogram.
On the nonfunctional side, tooth contacts varied from 0 to 2 on 1.5 mm laterotrusion and from 0 to 3 on 3 mm laterotrusion. The median values were 1 and 0 on 1.5 mm and 3 mm laterotrusion. Tooth contact on the nonfunctional side combined with contact on the functional side, or balanced occlusion, was discovered in approximately half of the subjects on 1.5 mm laterotrusion and in approximately a third on 3 mm laterotrusion. A nonfunctional side interference or tooth contact only on the nonfunctional side was rare. The details of the dentitions and the patterns of tooth contacts were documented in Ingervall et a1.6
Analysis
of dental
casts
Dental stone casts were made from irreversible hydrocolloid impressions. The width of the dental arches between the canines and the first molars was measured with sliding calipers and read to the nearest 0.1 mm. The reference points for maxillary molars were the central fossae. The mandibular molars were measured at the tips of the distobuccal cusps and the incisal tips were recorded for the canines. When the cusp tip was abraded, the approximate center of the abraded surface was designated. The vertical and horizontal overlaps including the mesiodistal relations of the first molars were measured with the casts secured in the intercuspal position. Vertical and horizontal overlap were measured to the nearest 0.5 mm on both central incisors by use of the method of Lundstroem,14 The mesiodistal molar relation was determined by superimposing the mesial surface of one molar on the other, and the distance between the maxillary and mandibular mesial surfaces was measured to the nearest 0.1 mm with sliding calipers (Fig. 1).
THE
JOURNAL
OF PROSTHETIC
DENTISTRY
Fig. 4. Reference points for analysis of frontal cephalogram.
Radiographic
cephalometry
Profile and frontal or posteroanterior cephalograms were obtained with the mandible at the intercuspal position with the Frankfort plane horizontal. In the profile cephalogram, the linear enlargement was 3.3% and in the frontal cephalogram 5% for structures in the frontal plane through the porion. The reference points and lines used in the analysis of the profile cephalogram are shown in Figs. 2 and 3, and the reference points in the analysis of the frontal cephalogram in Fig. 4.
RESULTS The results of the analysis of the dental casts (Table I) and those of the cephalometric analysis (Table II) revealed a wide variation in the morphology of both the dentition and the face.
Correlation between number contacts and facial morphology
of tooth
The relationship between the tooth contacts in the different mandibular positions and the morphologic variables was computed by use of a Spearman rank correlation.
Retruded
position
The tooth contacts in the retruded position were significantly correlated with two morphologic variables, the mesiodistal molar relation on the left side (rho -0.23, 0.01
