Introduction
Class II mal-occlusion and its non-extraction treatment approach are often quite a garbled decision for an orthodontic professional, because it has varied modalities to it depending on variety of factors such as patients facial type and profile, malocclusion of the teeth, age of the patient, overjet and overbite and lots of more. Class II mal-occulsion treatment without removing any teeth requires distalisation of maxillary dentition, or protraction of the mandibular dentition or combination of both; is a sine qua non. Various appliances have been used over time to distalise the maxillary molars, with no disposition to question their veracity. However patient co-operation remains the main concern, and the various mechanics used require minimal patient co-operation and are quite discernible and relevant.1, 2 Intra oral devices for maxillary molar distalisation like the pendulum, push coils, magnets, super-elastic NiTi coil springs and wires, distal jet and therefore the molar sliders etc.3, 4, 5, 6, 7, 8 Although these appliances distalise both 1st and 2nd molars effectively, but also always exert reciprocal adverse side effects; which are mostly the forward movement of the anterior teeth which is contra-indicated within the non-extraction treatment protocol in most cases. These factors definitely offset the treatment effects and liability of the appliances, these adverse effects should be minimized as much possible. The answer to these limitations has been deciphered by recent advances in implant dentistry and radiography.9 With the utilization of dental mini-implants and mini-plates as anchorage, the distal movement of anterior or posterior teeth or both without anchorage loss has become possible.10, 11, 12, 13 Among these devices, mini implants are advantageous due to its easy placement and removal but it does have its share of setbacks being the failure rate with respect to long term retention and stability over the course of treatment. Hence mini-plates take over the dogmata of the mini-implants, although it requires special minimal surgical technique and anatomic specificity for its placement but is very aberrant when it comes to retention and stability over a long period of time and minimal patient cooperation. Sliding mechanics with the help of mini-plate assisted anchorage and its application for treatment of skeletal class I and class II malocclusion have been described and its application in non-extraction treatment will be enlightened. The subsequent case reports the utility of mini-plates as an absolute anchorage for distalisation of upper molars.
Diagnosis
A 23yr old male patient reported with end-on molar relation on both right and left side, moderate crowding in both maxillary and mandibular dentition, normal maxillamandibular relation with class II division 2 features anteriorly(Figure 1). Distalisation of the maxillary molars was planned and extractions were avoided as the patient had a straight pleasing profile. Miniplates were considered to serve the purpose for both distalisation and anchorage. Crowding in the lower arch was relieved by proclining the teeth and mild stripping.
Treatment outlay and progress
Upper 1st and 2nd molars were involved and 0.022" MBT system of brackets were used for the entire arch from 2nd premolar to 2nd premolar on both the sides. After aligning the anterior teeth, a segmental 0.019" × 0.025" stainless steel wire was placed to prevent distal tipping and rotation of molars. After this two y-shaped titanium miniplates were placed on both sides at the level of centre of resistance of the maxilla, zygomatic buttress area above the upper 1st and 2nd molar region acquiring the zygomatic anchorage.14
After a week, the miniplates were loaded with e-chain from the crimpable hook between the canine and lateral incisor with 0.019 x 0.025 inch stainless steel wire in place for distalisation.
In a month’s time, the right molar was distalised by 2mm and left molar by 1mm. After 3 months, molar distalisation of 3mm and 4mm was achieved on right and left side simultaneously. After achieving the required distalisation, ideal overjet and over bite was achieved. Final settling of occlusion was also achieved.
Treatment effects
A full cusp Class I molar and canine relation on both sides was achieved with appreciable alignment in both the arches without any premolar extractions. The profile was also improved pleasingly.
Table 1
Cephalometric comparision table
Discussion
A major disadvantage of devices which are used for distalizising the upper molars is reciprocal opposite movement of premolars and anterior teeth in mesial direction. But during this case i.e. class II division 2 case the forward movement of anterior teeth was needed for better over-jet and overbite. Otherwise in other cases where molar distalization is done there is always some amount of anchor loss in form of maxillary anterior proclination. now we have to correct this anteriorly moved teeth by creating space by distalizing molars, where molars are used as an anchorage. Thus molars are strained and it affects the efficiency of distalizing devices. Moreover, there is a round-tripping as incisors are proclined during the distal movement of the molars and then again they are retracted into the space created by distalized molar. However in case of miniplates the entire buccal segment can be distalized without any strain on the anterior teeth. So use of miniplates don't produce any undesirable effect on the incisors.14 A systematic review by Antonarakis and Kiliaridis states that that tooth-borne distalizing applainces can move upper molars distally by around 2.9 mm; but there is undesirable mesial movement of incisors by 1.8mm.15 The findings of this case indicate that the orthodontic miniplates can be used as absolute anchorage with maximum molar distalization without any adverse effect on the incisors. When similar studies for distalization were compared, it was shown that the mean distal movement of upper molars is between 3.9mm to 6.4mm. All these studies also show that there is no adverse effect on the incisors and they remained stable. This clearly suggests that the distalization with miniplates is far superior to intraoral tooth born distalizing appliance.14, 15, 16
Conclusion
Distalisation of the molars or entire buccal posterior segment in maxillary arch can be successfully achieved by using the miniplates. In addition they shorten treatment duration as entire buccal posterior segment can be distalised without any adverse effect on the inciors. So, in cases such as Class II division 2 with straight profile and where extraction is contraindicated, molar distalization using plates could be the best option.
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