CLINICAL FEATURE
Fig. 2: A “ghost IPR” can be created to reduce minute gaps less than 0.2mm which scanning software might not detect
Fig. 1: Before (left) and after of a patient with a POB > 1mm at the end of treatment and one month after elastic wear
Fig. 3: A patient’s progress over three months where a fixed sectional appliance was used in conjunction with the last aligner (hybrid appliance) to resolve a POB at end of treatment
ABOUT THE AUTHOR
These brackets should be bonded near the gingival margin with the molar tubes bonded with a mesial tube angulation (mesiobuccal cusp vertical height at x+0.5mm and distobuccal cusp vertical height at x-0.5mm). Next, the gingival half of the aligners on the buccal surface are cut away leaving the occlusal half of the buccal to serve as guide rails to guide teeth into correct positions, creating a hybrid aligner (Fig. 3). The angulated tube technique can be applied with the following archwire sequence: 0.014 Niti → 0.016X0.016 Niti and finishing in 0.016 X 0.022 Niti. EXCESSIVE ORTHODONTIC HYPERMOBILITY IN ANTERIOR TEETH This could be due to a premature contact (high bite) on one of the anterior teeth. Occlusal equilibration of the high bite would resolve this after determining the defaulting tooth with articulating paper. PERSISTENT SPACE NOT CLOSING EVEN DURING REFINEMENTS This could be because the scanners will tend to “digitally patch up” 0.1-0.2mm spaces that could be present in the maxillary or mandibular arches and will show up in the scans as no diastemas even though they exist
clinically. This often results in the final aligner not closing the space.
To manage such situations, the clinician can instruct the treatment simulation team to do a “ghost IPR” (Fig. 2). A “ghost IPR” is a term used to ask aligner companies to tighten contact points by virtually creating a small 0.2mm space to allow aligners to tighten contact points, but these spaces are not performed clinically. SUMMARY With the multitude of aligner systems available in the market today, more and more clinicians are incorporating clear aligners into their daily dental practice. The above summarises the common problems clear aligner clinicians could encounter during the finishing stages and how to apply simple techniques to enhance the finished results for clear aligners. DA ACKNOWLEDGEMENTS The above are excerpted from Dr Kenneth Lew’s Clear Aligner Modular Program Chapter 23 conducted with the College of General Dental Practitioners in Singapore and Ancora Imparo in Malaysia since 2020.
Educated in Singapore under the well-regarded Public Service Commission
Scholarship, Dr Kenneth Lew obtained his Bachelor of Dentistry (BDS) from National University of Singapore (NUS) before attaining his Master of Dental Surgery in Orthodontics (MDS) from the University of Adelaide under a National University of Singapore Postgraduate scholarship. Dr Lew received the Fellowships from the Royal College of Surgeons of Edinburgh (FDSRCS) as well from The Academy of Medicine (FAMS). Thereafter, Dr Lew served many fulfilling years teaching, academic research and as a clinician with NUS. He currently works as a Specialist Orthodontist in Tanglin Dental Surgeons which he founded, as well as an international speaker and trainer sharing his expertise in clear aligners and fixed appliances in many countries.
37 DENTAL ASIA SEPTEMBER / OCTOBER 2024
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