Is Lower Canine Braces Can Interchangeable For Uppers In Mbt System

Tapered aren form

Figs 2.43 and 2.44 Arch form is an important factor in selection of canine brackets in upper and lower arches.

Prominent Canine With Brace

Fig. 2.45 A case with prominent canine roots at the start of treatment, where canine retraction was required. Accordingly, zero torque upper and lower canine brackets are in place to assist treatment mechanics.

Overbite Lower Canine Bracket Mbt

Canine prominence

The -7° upper and -6° lower torque canine brackets are normally not correct if the patient has prominent canines, or canine gingival recession, at the start of treatment. Brackets with 0° torque or +7° upper and +6° lower torque should be selected (Fig. 2.45).

Overbite

In Class II/2 cases and other deep bite situations there is often a requirement to move the lower canine crowns labially, but to maintain the roots centered in the bone. This is more easily achieved if 0° or +6° lower canine brackets are selected (Fig. 2.46).

Fig. 2.45 A case with prominent canine roots at the start of treatment, where canine retraction was required. Accordingly, zero torque upper and lower canine brackets are in place to assist treatment mechanics.

Fig. 2.46 If lower canine brackets with 0° or +6° of torque are used, this facilitates moving the canine crowns labially while maintaining the roots centered in the bone. This is helpful in managing deep bite situations in some cases.

The extraction decision (tip control)

Many clinicians believe that the -7° upper and -6° lower torque canine brackets are not ideal for premolar extraction cases, or in cases where there is considerable canine tip to be corrected during treatment. They prefer brackets with 0° torque for use with canine retraction mechanics and in any case where it is necessary to substantially change canine tip. The thinking behind this view is that the 0° brackets tend to maintain the canine roots in cancellous bone, thereby making tip control of the canine roots easier. The 0° canine bracket carries a hook, as it is often considered for cases which require canine retraction (Fig. 2.45) or Class II mechanics.

Rapid palatal expansion cases

After rapid palatal expansion, widening of the upper arch creates a secondary widening in the lower arch. There are torque changes (uprighting) among the lower teeth3 and 0° or +6° lower canine brackets are recommended to assist this favorable change.

Lower Dog Braces

Fig. 2.47 This case had agenesis of the upper right lateral incisor. Versatility features of the MBT™ system are being used to assist treatment mechanics. The upper right canine bracket is inverted 180°. The upper right first permanent molar carries a lower left second molar bonded tube with zero rotation to assist in achieving a good Class II molar relationship at the end of treatment (Fig. 2.58, p. 51).

Agenesis of upper lateral incisors, where space is to be closed

If one or both upper lateral incisors are missing, a decision may be made to close the spaces, and bring the canines mesially into contact with the central incisors. In this situation, it is helpful to invert the -7° upper canine bracket 180°. This changes the torque to +7°, but the tip stays the same at 8°. The left side bracket is placed on the left canine and the right side bracket is placed on the right canine. It is not correct to place the left canine bracket on the right canine or vice versa.

The inverted canine bracket is well adapted to the tooth surface, and the in-out dimension will be correct. At (he rectangular wire stage, this helps to torque the canine root into a palatal position with a minimum of wire bending (Fig. 2.47).

Fig. 2.47 This case had agenesis of the upper right lateral incisor. Versatility features of the MBT™ system are being used to assist treatment mechanics. The upper right canine bracket is inverted 180°. The upper right first permanent molar carries a lower left second molar bonded tube with zero rotation to assist in achieving a good Class II molar relationship at the end of treatment (Fig. 2.58, p. 51).

Fig. 2.49 Lower incisor brackets have zero tip, and are Fig. 2.50 Intra-oral radiographs showing parallel lower incisor interchangeable. roots in the case featured in the adjacent photograph.

Interchangeable

Fig. 2.48 The 0" tip feature of the lower incisor brackets allows them to be interchangeable.

Fig. 2.49 Lower incisor brackets have zero tip, and are Fig. 2.50 Intra-oral radiographs showing parallel lower incisor interchangeable. roots in the case featured in the adjacent photograph.

Interchangeable lower incisor brackets

For the lower incisor brackets, 0" tip was used to reflect the research findings, and to make less demand on lower arch anchorage. An additional benefit is that the 0° tip allows all the lower incisor brackets to be interchangeable (Figs 2.48-2.50), thereby assisting inventor)' control.

Interchangeable

Fig. 2.48 The 0" tip feature of the lower incisor brackets allows them to be interchangeable.

Fig. 2.51 The 0° tip feature of the premolar brackets allows them to be interchangeable between left and right sides, and between first and second premolars.

Interchangeable upper premolar brackets

Similar comments can be made concerning the upper premolar brackets. The bracket system was designed with 0° tip for all the upper premolars, to make less demand on anchorage, and to assist in achieving a Class I relationship. The 0° tip allows them to be interchangeable (Figs 2.51-2.54), which helps inventory control.

Fig. 2.51 The 0° tip feature of the premolar brackets allows them to be interchangeable between left and right sides, and between first and second premolars.

Figs 2.52 to 2.54 Upper premolar brackets have zero tip, and are interchangeable both between first and second premolars and between the left and right sides. The canine roots are well positioned, with correct tip.

Interchangeable

Use of upper second molar tubes on first molars in non-HG cases

The recommended specification for upper first and second molars is -14° torque, 0° tip, and 10° anti-rotation. The upper second molar tube may therefore be used on the upper first molars, for cases where headgear will not be required (Figs 2.55 & 2.56).

Fig. 2.55 Upper second molar attachments may be used on upper first molars in cases where headgear is not required.

Fig. 2.56 This non-extraction case did not require headgear support, and an upper second molar tube was bonded onto the upper first molar.

Fig. 2.57 The upper second molar tube may be used on upper first molars for cases where headgear is not needed.

Fig. 2.56 This non-extraction case did not require headgear support, and an upper second molar tube was bonded onto the upper first molar.

Fig. 2.57 The upper second molar tube may be used on upper first molars for cases where headgear is not needed.

www.allislam.net

Use of lower second molar tubes for the upper first and second molars of the opposite side, when finishing cases in a Class II molar relationship

It is often difficult to achieve good finishing and detailing in cases which are treated to a Class II molar relationship, after extraction of two premolars in the upper arch only.

It helps if upper molar tubes can he used which will deliver zero rotation (compared with the normal 10° rotation) and zero tip (compared with the normal 5° tip). This versatility can be achieved by using lower second molar tubes for the upper molars, and changing sides, left going to right, and right to left (Figs 2.58-2.60). Also the tube is placed at a different tip position, with more enamel from the mesial cusp visible than from the distal cusp. This introduces the necessary tip adjustment.

In some of these cases, it is correct to use normal upper molar tubes to achieve most of the treatment objectives, and then to switch to lower second molar tubes for finishing. The lower second molar tubes may be used from the outset in cases where a lot of treatment mechanics will not be needed.

Fig. 2.58 When finishing cases in a Class II molar relationship, it can be helpful to place lower second molar attachments on upper first and second molars of the contralateral side during the finishing stages. The lower attachments have 0° rotation, and normally in these cases it is appropriate to encourage upper molars to rotate mesio-palatally. A 0° rotation molar attachment is therefore preferable to the normal upper molar attachment, which has 10° rotation.

Fig. 2.58 When finishing cases in a Class II molar relationship, it can be helpful to place lower second molar attachments on upper first and second molars of the contralateral side during the finishing stages. The lower attachments have 0° rotation, and normally in these cases it is appropriate to encourage upper molars to rotate mesio-palatally. A 0° rotation molar attachment is therefore preferable to the normal upper molar attachment, which has 10° rotation.

Figs 2.59 and 2.60 A decision was made to treat this case to a Class II molar result. Lower second mola.r tubes, which have zero rotation, are being used on the contralateral side of the upper arch on first and second molars to assist in. achieving good mol-ar occlusion. .;-'".'" .'■ .""

ADDITIONAL BRACKET AND TUBE OPTIONS

Since the bracket system was released in May 1997, the MBT™ treatment philosophy has been continually evolving and improving, in response to clinical experience and user input. The option of the thicker upper second premolar bracket has been available from the outset, but other useful options have been added since the initial release, which have further enhanced the versatility. Some of them are reviewed below.

Bracket for small upper second premolars

In daily practice, upper second premolars are sometimes small. An alternative bracket, which is 0.5mm thicker than normal, is useful for such teeth (Fig. 2.61). This bracket is helpful in obtaining good alignment of marginal ridges in cases with small upper second premolars. It requires care with bonding, as its greater prominence makes it more vulnerable to biting forces. Only a small inventory of upper second premolar brackets is required, and this should be monitored bv one staff member.

Lower second premolar tubes

These were developed and tested in 2000, and are likely to find a place in the future of orthodontic treatment mechanics. This radical development has been made possible by the flexibility of the .016 IIANT wires, which can easily be threaded through lower second premolar lubes at the start of treatment, even if there are slight rotations present (Fig. 2.62).

Fig. 2.62 Lower second premolar tubes viewed from the occlusal. A rectangular HANT wire has been placed without difficulty.

Normal bracket

Normal bracket

0.5 mm thicker bracket

0.5 mm thicker bracket

Fig. 2.62 Lower second premolar tubes viewed from the occlusal. A rectangular HANT wire has been placed without difficulty.

Lower second premolar tubes are cleaner and more comfortable than conventional brackets. Their reduced bulk causes fewer interferences and breakages in this area, where in the past breakages have often occurred. Normal sliding mechanics (Figs 2.63 & 2.64) can be achieved in a virtually friction-free manner, and the lower second premolar tubes are self (¡gating, which saves a small amount of chairside time at each visit.

Fig. 2.61 The thicker bracket option for small upper second premolars is helpful in achieving good alignment of marginal ridges without wire bending.

Fig. 2.63 Appliance breakages in the lower second premolar regions are frequently encountered, even with careful bonding, when regular brackets are used.

Fig. 2.65 Lower first molar non-convertible tubes have many advantages over the traditional, more bulky, convertible lower first molar attachments.

Fig. 2.63 Appliance breakages in the lower second premolar regions are frequently encountered, even with careful bonding, when regular brackets are used.

Lower first molar non-convertible tubes

These have many advantages over the more bulky convertible lower first molar attachments. Tubes are more comfortable, cleaner, and stronger than the conventional convertible brackets (Fig. 2.65). Their reduced bulk causes fewer interferences in this important area, and this in turn makes it easier to achieve accurate vertical bracket positioning. For these reasons, lower first molar non-convertible tubes are becoming the attachment of choice in many practices, in preference to (he more bulky convertible lower first molar attachments.

Fig. 2.64 The lower second premolar tube is more comfortable and is normally less liable to breakages than the equivalent bracket.

Lower first molar double tube and upper first molar triple tube attachments

These were introduced for cases where segmental mechanics are appropriate for the case. Segmental mechanics are seldom used by the authors, and they generally favor a gingival HG tube. These attachments are useful for clinicians who previously have used a segmental approach, and are in transition to the MBT™ philosophy, which is based on full arch mechanics.

Bondable mini second molar tubes

In instances where a second molar needs to be included, but the tooth is insufficiently erupted lor band placement, a small tube can be bonded to the mesio-buccal area (Figs 2.66 & 2.67). These are comfortable and surprisingly effective for aligning the second molar.

Figs 2.66 and 2.67 In this case, viewed from the buccal and the occlusal, tubes are in place on the lower second premolar and both lower molars. The bondable mini second molar tubes (3M Unitek 066-5044, 066-5033) are most useful when the lower second molar is only partly erupted, and are surprisingly effective in clinical use.

REFERENCES

1 Andrews L F 1972 The six keys to normal occlusion. American Journal of Orthodontics 62:296-307

2 Sebata E 1980 An orthodontic study of teeth and dental arch form on the Japanese normal occlusions. The Shikwa Gakuho 80(7):945-969

3 Watanabe K, Koga M, Yatabe K, Motegi E, Isshiki Y A 1996 A morphometry study on setup models of Japanese malocclusions. The Shikwa Gakuho

4 Bennett J, McLaughlin R P 1997 Orthodontic management of the dentition with the preadjusted appliance. Isis Mcdical Media, Oxford (ISBN 1 899066 91 8) pp. 283-288. Republished in 2002 by Mosby, Edinburgh (ISBN 07234 32651)

5 Sandstrom R A, Klapper L, Papaconstantinou S 1988 Expansion of the lower arch concurrent with rapid maxillary expansion. American Journal of Orthodontics 94:296-302

Was this article helpful?

0 0
Booze Basher

Booze Basher

Get All The Support And Guidance You Need To Permanently STOP The Battle With Alcohol Once And For All. This Book Is One Of The Most Valuable Resources In The World When It Comes To Transformational Tools For Battling Booze Binges And Staying Alcohol-Free.

Get My Free Ebook


Responses

  • marina bader
    Is lower canine braces can interchangeable for uppers in MBT system?
    4 years ago
  • Felix
    When did sebata released the mechanic?
    4 years ago
  • Mebrahtu
    Why premolars brackets are interchangeable?
    8 months ago

Post a comment