Abstract
Among all the variables in Hanau’s quint for achieving a bilaterally balanced occlusion, compensating curves are of paramount importance. Multiple methods for incorporating these curves in denture occlusion have been proposed. However, the equipment used to achieve this has certain limitations for inexperienced dental practitioners and technicians. This article discusses the use of a denture teeth arrangement jig with three-dimensional printed tooth positioning blocks, to subdue the challenges faced currently, and anticipates its use as an alternate method while arranging denture teeth. The purpose of the device is to precisely introduce the intended bilaterally symmetrical compensatory curves during denture teeth arrangement in less time.
Keywords: Balanced occlusion, compensating curves, denture teeth, modified jig, teeth arrangement, three-dimensional printing
Introduction
In accordance with the recent evidence-based consensus on complete denture occlusion, it is well established that the occlusal scheme considered for edentulous patients presenting with increased alveolar bone loss, inadequate stability, and retention is bilaterally balanced occlusion (BBO).[1] The variables which can be manipulated by the operator to achieve a BBO are expressed by Thielemann’s formula. The compensating curves (CCs), namely, the curve of Spee and the curve of Wilson, compensate for the discrepancy between the inclination of condylar guidance (CG) and actual cusp angulation of posterior denture teeth and create an effective cusp angle in harmony with the CG therewith.[2] Therefore, CCs play a pivotal role in achieving the BBO.
To obtain this occlusal scheme, either the mandibular posterior teeth or the maxillary posterior teeth can be arranged first in sequence.[3] Incorporating the CCs in the mandibular dentures after following a predetermined occlusal plane relation for maxillary posterior teeth first, has been proposed by various authors.[4] Conventionally, a lecron carver or manual finger pressure is used to position each cusp of maxillary denture posterior teeth in accordance to the suggested clearance from the occlusal plane [Table 1].[4,5] This helps in achieving a tentative predetermined CC, which is closer to the final CC attained after achieving the BBO. However, when manually done by inexperienced dental technicians and clinicians, it is arbitrary, technique-sensitive, and time-consuming, and the CCs attained on both sides are seldom homogenous. Although digital denture techniques are gaining acceptance with time, but many clinicians are reluctant to incorporate them into their practice due to high initial setup cost, maintenance, and lack of training in digital denture fabrication.[6] Curved metal and plastic jig templates for arranging mandibular denture teeth to incorporate CCs are commercially available and have been mentioned in studies, but they can be attached only to a specific articulator system.[7] To the best of the authors knowledge, no attempt has been made to fabricate a positioning jig for maxillary denture posterior teeth.
Table 1.
Distance of maxillary posterior cusps from occlusal plane
| Maxillary posterior tooth | Buccal cusp (mm) | Palatal cusp (mm) | ||
|---|---|---|---|---|
| PM1 | 0 | 0 | ||
| PM2 | 0 | 0 | ||
|
| ||||
| Maxillary posterior tooth | Mesio-buccal cusp (mm) | Disto-buccal cusp (mm) | Mesio-palatal cusp (mm) | Disto-palatal cusp (mm) |
|
| ||||
| M1 | 0.5 | 1 | 0 | 0.5 |
| M2 | 1 | 1.5 | 0.5 | 1 |
PM1: 1st premolar; PM2: 2nd premolar; M1: 1st molar; M2: 2nd molar
Therefore, to overcome the previous shortcomings, this article discusses a simplified technique for arranging complete denture teeth using an arrangement jig with three-dimensional (3D) printed tooth positioning blocks.
Procedure
The arrangement jig device comprises 3D-printed tooth positioning blocks, one base plate, and one cover plate. The average dimensions of the occlusal table and cusps of medium-sized maxillary posterior acrylic denture teeth (AcryRock acrylic teeth D35-45, Ruthenium Dental Products Pvt. Ltd.) were recorded. As shown in Figure 1a, the virtual design of tooth positioning blocks was created using CAD software (SOLIDWORKS, Dassault Systems – SolidWorks Corporation), and later 3D printed in a fused deposition modeling printer (Markforged, Phillips Machine Tools India Pvt. Ltd.) using Polyethylene Terephthalate Glycol material (PETG Solid gold 1.75 mm, Shenzhen Esun Industrial Co Ltd.). As shown in Figure 1b and c, the height x of the 3D-printed block corresponds to the thickness of the acrylic base plate, y corresponds to the cusp positioning elevations, and the horizontal stopper secures the resin blocks in the slot of the base plate. As shown in Figure 1c, total of eight slots, four on each side of the base plate correspond to the dimensions of 3D printed blocks for 1st premolar, 2nd premolar, 1st molar, and 2nd molar. When aligned on the base plate, the arch slot in the cover plate accommodates the occlusion rims of varying arch width and forms an elevated boundary for the 3D-printed blocks to confine the lateral contour of the maxillary posterior arch form [Figure 2a and b]. These slots on the base and cover plates were precisely cut using a CO2 acrylic laser cutting machine (CMA-960 T, Prakash Machineries Pvt. Ltd.).
Figure 1.
CAD model of denture tooth positioning block for a right maxillary first molar (a), Three-dimensional printed denture tooth positioning block (b), Labeled component parts of denture teeth arrangement jig (c)
Figure 2.
Top view of arrangement jig (a), Side view of arrangement jig depicting the prominence of three-dimensional printed tooth positioning block (b), Cusps of all posterior teeth in contact with acrylic base plate (c)
The technique followed to achieve the bilaterally symmetrical CCs is outlined below.
Arrange all the cusps of maxillary posterior teeth in contact with the occlusal plane, following a tentative lateral alignment as per the patient’s arch form [Figure 2c]
Uniformly soften the wax around the posterior teeth
Position the maxillary teeth of one side on the arrangement jig with each tooth opposing its corresponding 3D printed block and cover plate contacting the buccal surface of teeth
-
Press the denture base downwards towards the plate, until the occlusion rim wax completely contacts the base [Figure 3a], and repeat the same for the other side of the arch
The 3D printed resin block guided cuspal positions are now achieved in the maxillary posterior teeth [Figure 3b and c]
Arrange the opposing mandibular posterior teeth, and further refine the predetermined CC to achieve a BBO during excursive movements [Figure 4a and b].
Figure 3.
Posterior teeth of one side aligned on the corresponding tooth positioned block and pressed on the jig (a), Maxillary posterior cusps from occlusal plane aligned in accordance to predetermined compensating curves (b), Ideal lateral contour of the maxillary posterior arch (c)
Figure 4.
Working side contacts after achieving bilaterally balanced occlusion (BBO) (a), Nonworking side contacts after achieving BBO (b)
Discussion
This technique article describes a simplified method to introduce predetermined CCs in complete dentures before achieving a BBO, using 3D-printed denture tooth positioning blocks. The various advantages provided by the modified tooth positioning plate are, a short and simple learning curve, less time-consuming, enhanced precision and symmetrical prominence on both sides while incorporating the CCs, and, ease of visibility on a black acrylic plate due to better contrast than a glass plate. Moreover, along with the occlusal plane relation, the modified plate ensures the lateral alignment of maxillary posterior teeth at the same time.
Although the arrangement jig device was designed to achieve a conventional BBO for medium-sized anatomic teeth, the cusp positioners in the 3D-printed blocks may be modified according to the size of the teeth, or to achieve a lingualized balanced occlusal scheme. This technique does not propose achieving a definitive CC, as the CG values along with the desired prominence of CC may vary in every patient, and therefore would require further manual modification to achieve a refined BBO.
Conclusion
The teeth arrangement jig aids in achieving an initial predetermined reference position for maxillary posterior cusps, and precisely achieves bilaterally symmetrical compensatory curves during denture teeth arrangement in less time this may benefit the clinicians as well as dental technicians while achieving a BBO.
Conflicts of interest
There are no conflicts of interest.
Acknowledgments
The authors thank their teachers from Davangere, for their guidance and motivation, and the anonymous reviewers for their insightful suggestions. The authors thank Mr Sohil Chadha, for his constant support and motivation to the Department.
Funding Statement
Nil.
References
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