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The relationship between the mid-point and most-prominent point on the labial curve of upper anterior teeth.

Smith RN, Brook AH, Karmo M - Open Dent J (2009)

Bottom Line: Approximately 80% of upper central incisors had coincident mid- and most-prominent points.Upper lateral incisors and canine teeth had approximately 50% coincidence.The high proportions of non-coincident examples found suggest that clinicians should be aware of individual variation and that this may possibly effect 3(rd) order alignment.

View Article: PubMed Central - PubMed

Affiliation: Dental Sciences, University of Liverpool, UK. r.n.smith@liverpool.ac.uk

ABSTRACT

Objectives: This study investigates coincidence of the most-prominent point and the mid-point on upper anterior teeth in relation to the use of straight-wire appliances.

Materials and methods: Alginate impressions of the upper jaw were obtained from forty Caucasian patients. Impressions were cast using hard dental stone. The teeth on each upper study model (canine to canine) were marked along the facial axis of the clinical crown (FACC line) then separated using a very thin diamond disc. Each tooth was mounted on a glass slide using sticky wax and cut into two halves down this FACC line. Images were acquired of the sections and a straight line connecting the gingival margin and the incisal edge was drawn on the flat cut surfaces (now the proximal crosssectional view). From this line, perpendicular lines were drawn at the mid-point and most prominent point to the labial curve. Coincidence rate was calculated or whether the most prominent point was gingival or incisal to the mid-point.

Results: Approximately 80% of upper central incisors had coincident mid- and most-prominent points. Upper lateral incisors and canine teeth had approximately 50% coincidence. The vast majority of cases without coincidence showed the most-prominent point incisal to the mid-point for all tooth kinds with just 5% or less gingival.

Conclusions: The high proportions of non-coincident examples found suggest that clinicians should be aware of individual variation and that this may possibly effect 3(rd) order alignment.

No MeSH data available.


Related in: MedlinePlus

Proximal section of a central incisor displaying the variables.
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Figure 1: Proximal section of a central incisor displaying the variables.

Mentions: All practical work was carried out by one examiner. The upper anterior teeth on each study model (canine to canine) were marked along the facial axis of the clinical crown FACC line [4], with a thin pencil (size 0.3 mm). The FACC line was located manually using electronic callipers accurate to 0.01mm (Mitutoyo, Japan). A pencil line was placed down the centre of the labial surface to pass through 2 marks made halfway between the calliper widths at 2 different positions down the crown length. A line was then drawn through these points to meet with the gingival margin in one direction and the incisal edge in the other direction (Fig. 1). The teeth were individually separated using a very thin diamond disc (Microslice II precision slicing machine, Malvern Instrument, England) with a round annular blade having the cutting surface on the inner edge. The blade was approximately 17.5cm in diameter and 0.3mm thick. Each tooth was mounted on a glass slide using red wax and yellow sticky wax. The labial tooth surface was aligned parallel to the glass slide, so that the FACC line was perpendicular to the slide edge to aid alignment for cutting the tooth along this line. Information for later identification was added to each slide prior to cutting. The slides were placed on the platform beneath the cutting disc and adjusted such that the pencil line was parallel to the cutting edge of the blade. The platform of the machine was adjustable (0.01mm steps) facilitating precise positioning of the slide. Red and green marker spots were used for identifying the mesial and distal portion of each sectioned tooth and included in subsequent imaging.


The relationship between the mid-point and most-prominent point on the labial curve of upper anterior teeth.

Smith RN, Brook AH, Karmo M - Open Dent J (2009)

Proximal section of a central incisor displaying the variables.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2724645&req=5

Figure 1: Proximal section of a central incisor displaying the variables.
Mentions: All practical work was carried out by one examiner. The upper anterior teeth on each study model (canine to canine) were marked along the facial axis of the clinical crown FACC line [4], with a thin pencil (size 0.3 mm). The FACC line was located manually using electronic callipers accurate to 0.01mm (Mitutoyo, Japan). A pencil line was placed down the centre of the labial surface to pass through 2 marks made halfway between the calliper widths at 2 different positions down the crown length. A line was then drawn through these points to meet with the gingival margin in one direction and the incisal edge in the other direction (Fig. 1). The teeth were individually separated using a very thin diamond disc (Microslice II precision slicing machine, Malvern Instrument, England) with a round annular blade having the cutting surface on the inner edge. The blade was approximately 17.5cm in diameter and 0.3mm thick. Each tooth was mounted on a glass slide using red wax and yellow sticky wax. The labial tooth surface was aligned parallel to the glass slide, so that the FACC line was perpendicular to the slide edge to aid alignment for cutting the tooth along this line. Information for later identification was added to each slide prior to cutting. The slides were placed on the platform beneath the cutting disc and adjusted such that the pencil line was parallel to the cutting edge of the blade. The platform of the machine was adjustable (0.01mm steps) facilitating precise positioning of the slide. Red and green marker spots were used for identifying the mesial and distal portion of each sectioned tooth and included in subsequent imaging.

Bottom Line: Approximately 80% of upper central incisors had coincident mid- and most-prominent points.Upper lateral incisors and canine teeth had approximately 50% coincidence.The high proportions of non-coincident examples found suggest that clinicians should be aware of individual variation and that this may possibly effect 3(rd) order alignment.

View Article: PubMed Central - PubMed

Affiliation: Dental Sciences, University of Liverpool, UK. r.n.smith@liverpool.ac.uk

ABSTRACT

Objectives: This study investigates coincidence of the most-prominent point and the mid-point on upper anterior teeth in relation to the use of straight-wire appliances.

Materials and methods: Alginate impressions of the upper jaw were obtained from forty Caucasian patients. Impressions were cast using hard dental stone. The teeth on each upper study model (canine to canine) were marked along the facial axis of the clinical crown (FACC line) then separated using a very thin diamond disc. Each tooth was mounted on a glass slide using sticky wax and cut into two halves down this FACC line. Images were acquired of the sections and a straight line connecting the gingival margin and the incisal edge was drawn on the flat cut surfaces (now the proximal crosssectional view). From this line, perpendicular lines were drawn at the mid-point and most prominent point to the labial curve. Coincidence rate was calculated or whether the most prominent point was gingival or incisal to the mid-point.

Results: Approximately 80% of upper central incisors had coincident mid- and most-prominent points. Upper lateral incisors and canine teeth had approximately 50% coincidence. The vast majority of cases without coincidence showed the most-prominent point incisal to the mid-point for all tooth kinds with just 5% or less gingival.

Conclusions: The high proportions of non-coincident examples found suggest that clinicians should be aware of individual variation and that this may possibly effect 3(rd) order alignment.

No MeSH data available.


Related in: MedlinePlus