Increased vertical dimension of occlusion [VDO] in complete dentures is a common occurrence due to the fact that a method for its accurate, reliable, and convenient determination is unavailable. An approach to the re-establishment of a correct VDO is described in this study. The suggested method involves shortening of the denture teeth using guides, which is simple, time-saving, and inexpensive.

 
Most of the methods used to determine the vertical dimension of occlusion [VDO] in complete dentures utilize esthetics, phonetics, division of the face into equal thirds, pre-extraction photographs, pre-extraction dowels, distance of incisive papilla from mandibular incisor, parallelism of the ridges, measurement of former dentures, tactile sense, radiographs of condyle position and profile radiog­ raphs. None of these methods fulfill the require­ ments of accuracy, reproducibility and simplicity. Clinical judgement of the dentist becomes the deci­ sive factor in the establishment of VDO; con­ sequently inexperience on the part of the clinician may seriously compromise the outcome.
Young1 considered that incorrect VDO may so detrimentally modify orofacial physical values that esthetic appearance is totally lost. Pyott and Schaeffer2 reported that if either too small or too great a free way space is produced, undesirable symptoms would appear. Typical among these symptoms are fractured artificial teeth, midline fracture in denture bases, discomfort, poor reten­ tion, loss of alveolar bone associated with flabby ridges, temporomandibular joint pain, sore ridges and sore tongue. Silverman3 pointed out that an increased VDO of only 1 mm may be sufficient to produce difficulties in speech and mastication and/ or symptoms of discomfort. Heartwell and Rahn4 have suggested broadly that inadequate interocclusal distance should be corrected by alter­ ation of the occlusal surfaces of the teeth by means of remount procedures.
Methodical approach for modification of the VDO has not been reported in the literature. The objective of this article is to describe a step by step procedure for correcting increased VDO in com­ plete dentures.

Techniques

Most of the methods used to determine the vertical dimension of occlusion [VDO] in complete dentures utilize esthetics, phonetics, division of the face into equal thirds, pre-extraction photographs, pre-extraction dowels, distance of incisive papilla from mandibular incisor, parallelism of the ridges, measurement of former dentures, tactile sense, radiographs of condyle position and profile radiog­ raphs. None of these methods fulfill the require­ ments of accuracy, reproducibility and simplicity. Clinical judgement of the dentist becomes the deci­ sive factor in the establishment of VDO; con­ sequently inexperience on the part of the clinician may seriously compromise the outcome.
Young1 considered that incorrect VDO may so detrimentally modify orofacial physical values that esthetic appearance is totally lost. Pyott and Schaeffer2 reported that if either too small or too great a free way space is produced, undesirable symptoms would appear. Typical among these symptoms are fractured artificial teeth, midline fracture in denture bases, discomfort, poor reten­ tion, loss of alveolar bone associated with flabby ridges, temporomandibular joint pain, sore ridges and sore tongue. Silverman3 pointed out that an increased VDO of only 1 mm may be sufficient to produce difficulties in speech and mastication and/ or symptoms of discomfort. Heartwell and Rahn4 have suggested broadly that inadequate interocclusal distance should be corrected by alter­ ation of the occlusal surfaces of the teeth by means of remount procedures.
Methodical approach for modification of the VDO has not been reported in the literature. The objective of this article is to describe a step by step procedure for correcting increased VDO in com­ plete dentures.

Techniques

Clinical evaluation: Swallowing and relaxing of the jaw was used to obtain the physiologic rest position and vertical dimension of rest was measured. Several readings were taken and the most constant reading was considered as the vertical dimension of rest. The dentures in the mouth were critically analyzed for (i) the inter-occlusal distance and increased VDO in mm, and (ii) the amount of vertical height to be reduced from the upper and/or lower denture teeth.

       i.)   Preparation of indices: Dental stone indi­ ces were prepared for buccal and                             ingualdenture surfaces including  teeth  and flanges [Fig. 1]. A thin layer  of petroleum             jelly was applied on the teeth and polished surface of the dentures. The buccal surface             of the denture was mmersed in stone mix and held in posi­tion till the stone was set.                 The index was separated, trimmed, and labelled for identification. The procedures                 were repeated and indices were  made for other buccal and lingual surfaces of the                  dentures.
       ii.)  Marking guidelines: A line was marked on the buccal and lingual surfaces of the                     posterior teeth indicating the portions to be shortened from the occlusal surface [Fig.                 2] This line was transferred on the stone indices [Fig. 3].
       iii.)  Drilling along the central groove: Using a small round bur, a groove indicating the                   desired depth of the occlusal surface to be reduced was drilled along the central                      groove on the premolars and molars. A periodontal probe was used to ascertain the                     depth of the groove [Fig.4].
Tooth reduction: Even tooth occlusal surface reduction was carried out, with a fissure bur, up to the line marked on the teeth and to the depth of the groove. The exact amount of reduction was ensured by placing the indices on the denture [Fig. 5]. Tooth reduction is rep­ resented by dark areas in Fig.6and it shows unequal reduction from the occluding surfaces. The palatal slope of the upper cusps and buccal slope of the lower cusps were ground the same amount. At this stage the upper buc­ cal cusps and lower lingual cusps were higher than the other cusps. To achieve uniformity in cusp height, tooth reduction was carried out from the buccal slopes of the upper buccal cusps and lingual slopes of the lower lingual cusps. Incisal edges of the upper and/or lower anterior teeth were ground and shortened in keeping with esthetic and functional jaw movements.
Occlusal prematurities in centric and eccentric occlusion were detected and eliminated by selec­
tive grinding. Sharp line angles were rounded and ground surfaces were carefully finished and polished. Occlusion was checked in the patient's mouth and routine adjustments were carried out by clinical remount procedure.

 Establishment of correct VDO in complete dentures is a challenging task. Turvell5 stated that a scientifically- based method for assessing the VDO clinically is a pressing need and is of paramount importance. Whereas, Willie6 believed that as long as dentistry continues to deal with changeable physiologic tissues and individual variation, it is unlikely that any one standard method of determin­ ing VDO will ever be employed. In the absence of a reliable method, clinical judgement of the dentist becomes a decisive factor in determining VDO. This might result in complete dentures with increased or decreased VDO.
Complete dentures with increased VDO areoften discarded and new dentures are fabricated, which is time- consuming and expensive. Another alternative is to grind out all the teeth and replace them with new teeth on the old denture bases at the proper VDO. In the latter procedure, heat applied for curing the new added acrylic resin may cause dimensional changes in the already cured old denture bases.
In the technique described, it is essential to record the hinge axis as accurate as possible using arbitrary type of face bow to accommodate the change in VDO and the alterations of tooth
occlusal surfaces. Use of a kinematic face bow is not indicated because of the resilient lower denture foundation and the difficulty in attachment of the bitefork to the lower denture. Moreover, increased height of the lower denture may cause excessive opening of the jaw affecting translation of the con­ dyle heads in the temporomandibular joints. Equal amount of tooth reduction from the upper and lower denture teeth maintains the occlusal plane and a balanced occlusion remains undisturbed. Difficulties may arise when occlusal plane location is changed copiously. The shortcoming of the method described is shortening of the teeth, which may affect the esthetics adversely and, for that reason, proper selection of the case and patients consent becomes obligatory.
The method described to correct increased VDO in complete dentures promises the establishment of correct VDO and the technique is simple, inexpen­ sive, and time-saving.