- Email: [email protected]
Pressure exerted on teeth by the lips and cheeks
DEPARTMENT Edited
OF REVIEWS
AND
ABSTRACTS
by
h. J. A. Salzmann New York City A11 inqtiies regarding information on reviews and abstracts should be directed to the respective a&hors. Articles or books for review in this department should be addressed to Dr. J. A. Sa,lzmann, 654 Ma&so,!, A LT., IVeu: Pork, New Pork 10022.
Pressure Exerted J. K. LutRngham D. Practitioner
on Teeth
by the
Lips and
Cheeks
19: 61-64, October, 1968
Lip and cheek pressures were compared in three adult groups with different types of occlusion in an attempt to discover an association between pressure and arch form. Individuals showed a fairly consistent pressure pattern for each exercise, although there was considerable variation in the size of the pressures produced with each repetition. Different individuals produced markedly different pressure patterns. Since the variations between occa.sions seemed to be a real phenomenon, it was considered that pressure recordings from one individual upon a single occasion could not be regarded as typical of that individual. Therefore, no attempt was ma.de to compare individuals: instead, subjects were divided, on the basis of incisor overjet, into three groups corresponding to Angle’s Class I, Class II, Division 1, and Class III malocclusions. Overjet was defined as the horizontal distance bet.ween the labial surfac.cs of the upper and lower central incisors when the teeth were in centric occlusion. Subjects wit,h an overjet of 2 to 4 mm. formed the Class I group. Subjects with an overjet of 4.5 mm. or more formed the Class IT, Division 1 group, while subjects with an overjet of 1 mm. or less formed the Class III group. There were ten subjects in each group. In the maxillary first molar region all groups exhibited some buecal pressure during ‘5-M.” Although this pressure was small, there was a statistically highly significant. difference bet~-ce~~ the three groups. For the “swallow” oxcrc.ise there lvas no clifferrrlce l~e~wtcn groups. while for the “31” exercise the c’lass I and Class TI, Division 1 groups wcrc similar, with C’lass III exhibit,ing a lower pressure. The variation in subject performance on different occasions is thought to be important, as it appears large enough to invalidate the compa,rison of individuals upon the basis of a single recording. The factors which affect, skin elasticity must also affect the oral soft tissues and the forces which they exert upon teeth. JVhere these forces are increased by muscle activity, further variation will arise from the changing levels of cortical control over muscle action. Quite apart from the intrusion of recording 619
620
Amer. J. Orthodoltt.
Reviews and abstracts
Decembw1970
apparatus, the voluntary repetition of experimental exercises must raise to the level of consciousness muscle activity that would normally occur subconsciously. Thus, where soft-tissue forces are to be measured, a high degree of variation with time must be expected. Where an individual is compared at different times or where different subjects are compared on the basis of a single recording, any but gross differences are likely to be hidden by the high level of individual variation. For this reason, it is considered that the measurement of soft-tissue pressures can have little value as a clinical diagnostic method for individual patients. As a research tool, however, where groups of similar patients can be compared, it is a useful means to investigate factors affecting arch form.
Dental
Anatomy
Bertram
S. Kraus, Ronald
Baltimore,
and
Occlusion.
1969, The Williams
A Study
of the Masticatory
E. Jordan, and Leonard Abrams # WilLi%s Company. 317 pages, ill&rated.
System Price, $13.50
This scholarly text, with its excellent illustrations, is a source book that should prove valuable to dentists, dental teachers, and all who are concerned with dental anatomy and the occlusion of the teeth. The authors and the special contributors are recognized authorities in their respective fields, The text does, indeed, fulfill the aim of the authors to provide ‘(a single text that combines the anatomy of the individual teeth with an exposition of the total dental complex acting as a component of the masticatory system.” Part I presents the anatomy of the individual teeth. A glossary and a numerical nomenclature code are included which aid the student and general reader in identifying the morphologic details. Part II is devoted to the histology of the teeth and their investing structures. The text is concise and clearly presented with the aid of excellent photomicrographs. This reviewer has pointed out repeatedly in the pages of this JOURNAL and in texts that the masticatory system is a functional unit and that the orthodontist must take into consideration the effects of his therapy on the other components of the system. It is gratifying to note that the authors of this text stress the interdependence of the units of this functional complex to which the different components contribute. The self-protective features of the dentition as presented here provide an answer also to many questions on tooth positioning as it affects gingival health. Of practical value to the orthodontist is the description of the properties of the interproximal embrasure spaces created by the correct adjacent contacts of the teeth. “Since the interdental embrasure space is a primary site of dental disease,” the authors state, “it bears close surveillance in clinical practice.” This is a useful volume that can be used as a text by the student and a reference work by the practitioner. J. A. Salzmann
OF REVIEWS
AND
ABSTRACTS
by
h. J. A. Salzmann New York City A11 inqtiies regarding information on reviews and abstracts should be directed to the respective a&hors. Articles or books for review in this department should be addressed to Dr. J. A. Sa,lzmann, 654 Ma&so,!, A LT., IVeu: Pork, New Pork 10022.
Pressure Exerted J. K. LutRngham D. Practitioner
on Teeth
by the
Lips and
Cheeks
19: 61-64, October, 1968
Lip and cheek pressures were compared in three adult groups with different types of occlusion in an attempt to discover an association between pressure and arch form. Individuals showed a fairly consistent pressure pattern for each exercise, although there was considerable variation in the size of the pressures produced with each repetition. Different individuals produced markedly different pressure patterns. Since the variations between occa.sions seemed to be a real phenomenon, it was considered that pressure recordings from one individual upon a single occasion could not be regarded as typical of that individual. Therefore, no attempt was ma.de to compare individuals: instead, subjects were divided, on the basis of incisor overjet, into three groups corresponding to Angle’s Class I, Class II, Division 1, and Class III malocclusions. Overjet was defined as the horizontal distance bet.ween the labial surfac.cs of the upper and lower central incisors when the teeth were in centric occlusion. Subjects wit,h an overjet of 2 to 4 mm. formed the Class I group. Subjects with an overjet of 4.5 mm. or more formed the Class IT, Division 1 group, while subjects with an overjet of 1 mm. or less formed the Class III group. There were ten subjects in each group. In the maxillary first molar region all groups exhibited some buecal pressure during ‘5-M.” Although this pressure was small, there was a statistically highly significant. difference bet~-ce~~ the three groups. For the “swallow” oxcrc.ise there lvas no clifferrrlce l~e~wtcn groups. while for the “31” exercise the c’lass I and Class TI, Division 1 groups wcrc similar, with C’lass III exhibit,ing a lower pressure. The variation in subject performance on different occasions is thought to be important, as it appears large enough to invalidate the compa,rison of individuals upon the basis of a single recording. The factors which affect, skin elasticity must also affect the oral soft tissues and the forces which they exert upon teeth. JVhere these forces are increased by muscle activity, further variation will arise from the changing levels of cortical control over muscle action. Quite apart from the intrusion of recording 619
620
Amer. J. Orthodoltt.
Reviews and abstracts
Decembw1970
apparatus, the voluntary repetition of experimental exercises must raise to the level of consciousness muscle activity that would normally occur subconsciously. Thus, where soft-tissue forces are to be measured, a high degree of variation with time must be expected. Where an individual is compared at different times or where different subjects are compared on the basis of a single recording, any but gross differences are likely to be hidden by the high level of individual variation. For this reason, it is considered that the measurement of soft-tissue pressures can have little value as a clinical diagnostic method for individual patients. As a research tool, however, where groups of similar patients can be compared, it is a useful means to investigate factors affecting arch form.
Dental
Anatomy
Bertram
S. Kraus, Ronald
Baltimore,
and
Occlusion.
1969, The Williams
A Study
of the Masticatory
E. Jordan, and Leonard Abrams # WilLi%s Company. 317 pages, ill&rated.
System Price, $13.50
This scholarly text, with its excellent illustrations, is a source book that should prove valuable to dentists, dental teachers, and all who are concerned with dental anatomy and the occlusion of the teeth. The authors and the special contributors are recognized authorities in their respective fields, The text does, indeed, fulfill the aim of the authors to provide ‘(a single text that combines the anatomy of the individual teeth with an exposition of the total dental complex acting as a component of the masticatory system.” Part I presents the anatomy of the individual teeth. A glossary and a numerical nomenclature code are included which aid the student and general reader in identifying the morphologic details. Part II is devoted to the histology of the teeth and their investing structures. The text is concise and clearly presented with the aid of excellent photomicrographs. This reviewer has pointed out repeatedly in the pages of this JOURNAL and in texts that the masticatory system is a functional unit and that the orthodontist must take into consideration the effects of his therapy on the other components of the system. It is gratifying to note that the authors of this text stress the interdependence of the units of this functional complex to which the different components contribute. The self-protective features of the dentition as presented here provide an answer also to many questions on tooth positioning as it affects gingival health. Of practical value to the orthodontist is the description of the properties of the interproximal embrasure spaces created by the correct adjacent contacts of the teeth. “Since the interdental embrasure space is a primary site of dental disease,” the authors state, “it bears close surveillance in clinical practice.” This is a useful volume that can be used as a text by the student and a reference work by the practitioner. J. A. Salzmann