Jourtial of Oral Rehabilitatioti, 1992. 'Volume 19. pages .535-538
A new guide for positioning of maxillary posterior denture teeth A , S . E L - G H E R I A N l Departttietu of Piosthodontics, Arab Medical Uttiversity. Benghazi, Libya.
Suniniary
There is no definitive rnefhod for the arrangetnent of artifieial teeth in complete denture coristrucfion, A new rnefhod is introduced whereby the rna.xillary posterior teeth have been set in approximate positions mediolaterally similar to their natural predecessors. The procedure is based on a constant relationship derived from the natural dentition. Its clinical application proved to be suitable for the arrangement of artificial feeth for cotnplete dentures wifh minimal errors. Introduction
The arrangement of artificial teeth for complete dentures may appear to sotne experienced dentists and dental technicians a straightforward procedure. Different techniques have been advocated for the arrangement; for example placement over fhe residual ridges is widely used despite some published criticism (Pound 1954; Vig 1961), The neutral zone concept has been suggested for the mandibular teeth (Heath 1970; Murphy 1966), although it is not an easy method and has been criticised by Murray (1977), Clinically, many investigators have recotntnettded fhe arrangement of artificial teeth to be in the same relationship as the previous natural ones (Pound 1954; Waugh 1963), Other authors have suggested anatomical landmarks as guides for their corr'ect placement, (Grave & Backer 1987; Roraff 1977). The purpose of the present investigation was to evaluate a new method for the arrangement of artificial teeth for complete dentures in the approximate positions of the previous natural ones. This method is based on the results of a previous sttrdy reported by the author (El-Glieriani et al., 1989), Materials and methods
Forty edentulous patients (30 males, 10 females) were selected randomly. There was a varying degree of bone resorption and five had a previous history of poor denture foler'ance while one had a severe gagging rellex. The average age was 55 years with a range of 40—70, Each patient had one pair of primary and two pairs of secondary itn|^ressions taken by the same operator and two sets of record bases were constructed on the latter. After recording jaw relations and face-bow transfer, one pair of record bases was sent to a dental teehnician for the setting of the artificial teeth by conventional methods. The other pair of record bases was used by the author to set the maxillary and mandibular six anterior teeth according to accepted methods, which gave an Correspondence; Dr A,S, El-Gheriani, Department of Prostlunlontics. Faculty of Dentistry. Arab Medical University, P,O, Box 6416, Benghazi, Litiya, 535
536
A.S. El-Ghetiani
acceptable anterior try-in to operator and patient. The following method was used by the author to position the posterior feeth. The intercanine distance (C) was measured (Fig, 1) and a mathematical relationship between the buccal cusps of the maxillary posterior teeth on both sides and the intercanine distance was used as a guide for fhe positioning of fhe maxillary posterior teeth buccolingually (Fig, 2). This calculation is as follows:
c XX c
c XX
c cX cX
-2 = -4 = -5 = -6 = -7 = -7 =
disfance distance distance distance distance distance
between between between between between lietwecn
the the the the the the
buccal cusps of the first prernolars. buccal cusps of the second preniolar's. rnesio-buccal cusps of the first molar's, disfo-buccal cusps of the first molars, rnesio-buccal cusps of the second molars, disto-buccal cusps of the second molars.
The arrangenicnt of the maxillary posterior teeth starts with the placement of the first pr'cmolar on one side. By knowing the distances between the buccal cusps on both sides, the other premolar can then be placed in the approximate position. The same procedure is applied to arrange the whole upper posterior feeth following the compensating curves, 1 he occlusal rims play a major part in the setting of teeth by saving that part of the wax lying over' the tuberosity.
Fig. I. C = distanee between the canines as indieatcd by the dots.
Fig. 2. The mathematical calculation lo indicate the distanee between the buccal cusps of upper posterior teeth, C = the distance between the lingual inelination of the upper eanines.
Positlottlttg of ntaxlllary posterior dentttre teeth
537
Following a further try-in, the dentures were completed and inserted at weekly intervals, i,e. denture (A) teeth set by the conventional method given to the patient for 1 week. The following week denture (B) teeth set by the rnathemafical method to be given to the patient for 1 week. This was continued until all adjusttnents had been completed. At review each patient was asked about: (i) Function, mastication and speech; (ii) Comfort; (iii) Retention and stability; (iv) Aesthefics. Re.sul(s
1, At the try-in stage minimal correction was necessary for those dentures wifh feeth placed according to the rnathernafical method otrflined above. 2, On review rninirnal occlusal adjustment was carried out to the above dentui'es, with fewer visits by the patients, 3, Following the insertion of dentures for 40 pafienfs, 38 preferred those made with teeth set by fhe mathematical method. Two patients did not notice any differ'ence between the two sefs. Within the study if was noted that the difference in distance between the left and right side buccal cusps of upper posterior teeth for the finished dentures when using the two methods ranged between 0-2 to 4-00 mm. The distance between the upper posterior feefh was always greafer when using the rnafheinatical method. However when using conventional methods, fhe artificial teeth tended to be placed within the tongue space. Discussion A new method has been applied for setting complete denture feeth in the Faculty of Dentistry, Arab Medical University, Benghazi, Libya, with excellent results. The satisfactory application of this tnefhod depends on the initial positioning of fhe upper canines. This can be carried out by a variety of techniques apart from a subjective approach by the elinician, (a) Using the Gothic arch/intercanine distance relationship (El-Gher'iani & Winstanley, 1988), (Fig, 3); (b) Setting the upper six anterior teeth using anatomical landmarks e.g, the incisive papilla (Grave & Becker, 1987) or a combination of (a) and (b). Once the position of the canines is acceptable, tnathematical calctrlations can be applied for positioning the posterior teeth mediolaterally. Conclusion Recent studies have paid attention to the setting of the upper anterior teeth using anatomical landmarks as guides. In this paper a new method has been introduced for fhe arrangetnent of the upper posterior teeth using a constant tnathematical relationship derived from the natural dentition. In fhe author's judgement, by using the reported method, atificial teeth come to lie as a common result, within the neutral zone. A high pereentage of the patients preferred the dentures with teeth arranged by fhe new method. Future work involves development of a device designed to help in setting all posterior teeth at once following the rnathernafical calculation for each case. Acknowledgment The author wishes fo thank Mr R,B, Winstanley for his help and advice with the presentation of this paper and the secretarial staff of fhe Department of I^estorative Dentistry, School of Clinical Dentistry, University of Sheffield,
538
A.S. El-Gheriani
Fig. 3. The mathematical calculation to indicate the distance between the right and left upper buccal cusps of canines and the posterior teeth, GA = the width between the lateral arm of the Gothic areh traeing.
References EL-GIII',RIANI, A , S , , DAVII,:S, A , L , & WIN.SIANI.I'Y. R , B , (1989) The gothic arch tracing and the upper eanine teeth as guides in Ihe positioning of upper posterior tcclh. Journal of Otal Rehabilitation, 16, 481, Ei.-Grii'RrANi, A.S, & WINSIANI.HY, R , B , (1988) The value of gothie arch tracing in the positioning of denture teeth. Journal of Oral Rehabilitation, 15. 367, CjRAVii. A,M,G, & BiiCKER, P,J, (1987) Evaluation of Ihe ineisive papilla as a guide to anterior teelh position. Journal of Ptosthetic Dentistry, 57. 712, HuA'irr, R, (1970) A study of the morphology of Ihe denture space, Detttal Practitioner and Dental Recotd, 2t, 109, MURi'iiY, W,M, (1966) The nculral zone and the polished surfaces of full dentures. Dental Practitioner, 16, 244, MURRAY, C G , (1977) Anterior tooth positions in Prosthodonlies, Australian Dental Journal, 22, 113, PouNt), E, (1954) Lost — hnc arts in the lallaey of the ridges. Journal of Prosthetic Detitistry, 4. 6, RoRAi'i'. A,R, (1977) Arranging artificial teeth aeeording to anatomic landmarks, Jourtial of Prosthetic Dentistry, 11. 9, VIG. R . G , (1961) The denture look. Journal of Ptosthetic Dentistry, 11, 9, WAUCH, D . B , (1936) The arrangement of teeth in the natural and artiticial dentures. Dental Cosmos, 78, 1125,
A new guide for positioning of maxillary posterior denture teeth A , S . E L - G H E R I A N l Departttietu of Piosthodontics, Arab Medical Uttiversity. Benghazi, Libya.
Suniniary
There is no definitive rnefhod for the arrangetnent of artifieial teeth in complete denture coristrucfion, A new rnefhod is introduced whereby the rna.xillary posterior teeth have been set in approximate positions mediolaterally similar to their natural predecessors. The procedure is based on a constant relationship derived from the natural dentition. Its clinical application proved to be suitable for the arrangement of artificial feeth for cotnplete dentures wifh minimal errors. Introduction
The arrangement of artificial teeth for complete dentures may appear to sotne experienced dentists and dental technicians a straightforward procedure. Different techniques have been advocated for the arrangement; for example placement over fhe residual ridges is widely used despite some published criticism (Pound 1954; Vig 1961), The neutral zone concept has been suggested for the mandibular teeth (Heath 1970; Murphy 1966), although it is not an easy method and has been criticised by Murray (1977), Clinically, many investigators have recotntnettded fhe arrangement of artificial teeth to be in the same relationship as the previous natural ones (Pound 1954; Waugh 1963), Other authors have suggested anatomical landmarks as guides for their corr'ect placement, (Grave & Backer 1987; Roraff 1977). The purpose of the present investigation was to evaluate a new method for the arrangement of artificial teeth for complete dentures in the approximate positions of the previous natural ones. This method is based on the results of a previous sttrdy reported by the author (El-Glieriani et al., 1989), Materials and methods
Forty edentulous patients (30 males, 10 females) were selected randomly. There was a varying degree of bone resorption and five had a previous history of poor denture foler'ance while one had a severe gagging rellex. The average age was 55 years with a range of 40—70, Each patient had one pair of primary and two pairs of secondary itn|^ressions taken by the same operator and two sets of record bases were constructed on the latter. After recording jaw relations and face-bow transfer, one pair of record bases was sent to a dental teehnician for the setting of the artificial teeth by conventional methods. The other pair of record bases was used by the author to set the maxillary and mandibular six anterior teeth according to accepted methods, which gave an Correspondence; Dr A,S, El-Gheriani, Department of Prostlunlontics. Faculty of Dentistry. Arab Medical University, P,O, Box 6416, Benghazi, Litiya, 535
536
A.S. El-Ghetiani
acceptable anterior try-in to operator and patient. The following method was used by the author to position the posterior feeth. The intercanine distance (C) was measured (Fig, 1) and a mathematical relationship between the buccal cusps of the maxillary posterior teeth on both sides and the intercanine distance was used as a guide for fhe positioning of fhe maxillary posterior teeth buccolingually (Fig, 2). This calculation is as follows:
c XX c
c XX
c cX cX
-2 = -4 = -5 = -6 = -7 = -7 =
disfance distance distance distance distance distance
between between between between between lietwecn
the the the the the the
buccal cusps of the first prernolars. buccal cusps of the second preniolar's. rnesio-buccal cusps of the first molar's, disfo-buccal cusps of the first molars, rnesio-buccal cusps of the second molars, disto-buccal cusps of the second molars.
The arrangenicnt of the maxillary posterior teeth starts with the placement of the first pr'cmolar on one side. By knowing the distances between the buccal cusps on both sides, the other premolar can then be placed in the approximate position. The same procedure is applied to arrange the whole upper posterior feeth following the compensating curves, 1 he occlusal rims play a major part in the setting of teeth by saving that part of the wax lying over' the tuberosity.
Fig. I. C = distanee between the canines as indieatcd by the dots.
Fig. 2. The mathematical calculation lo indicate the distanee between the buccal cusps of upper posterior teeth, C = the distance between the lingual inelination of the upper eanines.
Positlottlttg of ntaxlllary posterior dentttre teeth
537
Following a further try-in, the dentures were completed and inserted at weekly intervals, i,e. denture (A) teeth set by the conventional method given to the patient for 1 week. The following week denture (B) teeth set by the rnathemafical method to be given to the patient for 1 week. This was continued until all adjusttnents had been completed. At review each patient was asked about: (i) Function, mastication and speech; (ii) Comfort; (iii) Retention and stability; (iv) Aesthefics. Re.sul(s
1, At the try-in stage minimal correction was necessary for those dentures wifh feeth placed according to the rnathernafical method otrflined above. 2, On review rninirnal occlusal adjustment was carried out to the above dentui'es, with fewer visits by the patients, 3, Following the insertion of dentures for 40 pafienfs, 38 preferred those made with teeth set by fhe mathematical method. Two patients did not notice any differ'ence between the two sefs. Within the study if was noted that the difference in distance between the left and right side buccal cusps of upper posterior teeth for the finished dentures when using the two methods ranged between 0-2 to 4-00 mm. The distance between the upper posterior feefh was always greafer when using the rnafheinatical method. However when using conventional methods, fhe artificial teeth tended to be placed within the tongue space. Discussion A new method has been applied for setting complete denture feeth in the Faculty of Dentistry, Arab Medical University, Benghazi, Libya, with excellent results. The satisfactory application of this tnefhod depends on the initial positioning of fhe upper canines. This can be carried out by a variety of techniques apart from a subjective approach by the elinician, (a) Using the Gothic arch/intercanine distance relationship (El-Gher'iani & Winstanley, 1988), (Fig, 3); (b) Setting the upper six anterior teeth using anatomical landmarks e.g, the incisive papilla (Grave & Becker, 1987) or a combination of (a) and (b). Once the position of the canines is acceptable, tnathematical calctrlations can be applied for positioning the posterior teeth mediolaterally. Conclusion Recent studies have paid attention to the setting of the upper anterior teeth using anatomical landmarks as guides. In this paper a new method has been introduced for fhe arrangetnent of the upper posterior teeth using a constant tnathematical relationship derived from the natural dentition. In fhe author's judgement, by using the reported method, atificial teeth come to lie as a common result, within the neutral zone. A high pereentage of the patients preferred the dentures with teeth arranged by fhe new method. Future work involves development of a device designed to help in setting all posterior teeth at once following the rnathernafical calculation for each case. Acknowledgment The author wishes fo thank Mr R,B, Winstanley for his help and advice with the presentation of this paper and the secretarial staff of fhe Department of I^estorative Dentistry, School of Clinical Dentistry, University of Sheffield,
538
A.S. El-Gheriani
Fig. 3. The mathematical calculation to indicate the distance between the right and left upper buccal cusps of canines and the posterior teeth, GA = the width between the lateral arm of the Gothic areh traeing.
References EL-GIII',RIANI, A , S , , DAVII,:S, A , L , & WIN.SIANI.I'Y. R , B , (1989) The gothic arch tracing and the upper eanine teeth as guides in Ihe positioning of upper posterior tcclh. Journal of Otal Rehabilitation, 16, 481, Ei.-Grii'RrANi, A.S, & WINSIANI.HY, R , B , (1988) The value of gothie arch tracing in the positioning of denture teeth. Journal of Oral Rehabilitation, 15. 367, CjRAVii. A,M,G, & BiiCKER, P,J, (1987) Evaluation of Ihe ineisive papilla as a guide to anterior teelh position. Journal of Ptosthetic Dentistry, 57. 712, HuA'irr, R, (1970) A study of the morphology of Ihe denture space, Detttal Practitioner and Dental Recotd, 2t, 109, MURi'iiY, W,M, (1966) The nculral zone and the polished surfaces of full dentures. Dental Practitioner, 16, 244, MURRAY, C G , (1977) Anterior tooth positions in Prosthodonlies, Australian Dental Journal, 22, 113, PouNt), E, (1954) Lost — hnc arts in the lallaey of the ridges. Journal of Prosthetic Detitistry, 4. 6, RoRAi'i'. A,R, (1977) Arranging artificial teeth aeeording to anatomic landmarks, Jourtial of Prosthetic Dentistry, 11. 9, VIG. R . G , (1961) The denture look. Journal of Ptosthetic Dentistry, 11, 9, WAUCH, D . B , (1936) The arrangement of teeth in the natural and artiticial dentures. Dental Cosmos, 78, 1125,
