{"id":58,"date":"2023-05-22T14:01:28","date_gmt":"2023-05-22T14:01:28","guid":{"rendered":"https:\/\/ekitap.ankara.edu.tr\/dentures\/chapter\/1-5-dis-destegi\/"},"modified":"2025-09-18T06:43:52","modified_gmt":"2025-09-18T06:43:52","slug":"1-5-dis-destegi","status":"publish","type":"chapter","link":"https:\/\/ekitap.ankara.edu.tr\/dentures\/chapter\/1-5-dis-destegi\/","title":{"raw":"Tooth support","rendered":"Tooth support"},"content":{"raw":"When determining teeth to serve as abutments for RPDs, their ability to resist functional stresses is a key consideration for ensuring controlled force transmission. The potential of a tooth to function as a reliable prosthetic abutment is assessed based on the following criteria:\r\n<ul>\r\n \t<li>Periodontal health<\/li>\r\n \t<li>Crown-to-root ratio<\/li>\r\n \t<li>Crown and root morphology<\/li>\r\n \t<li>Position within the dental arch<\/li>\r\n \t<li>Opposing occlusion<\/li>\r\n<\/ul>\r\n<h2 data-start=\"93\" data-end=\"773\"><strong data-start=\"93\" data-end=\"115\">Periodontal health<\/strong><\/h2>\r\n<p class=\"\" data-start=\"93\" data-end=\"773\">In evaluating abutment teeth for removable partial dentures, both clinical and radiographic findings must be carefully assessed. Since the terminal abutment teeth are subject to increased stress compared to non-supporting teeth, the quality and quantity of their alveolar bone support are of critical importance. Teeth exhibiting signs of periodontal lesions, infection, or clinical symptoms such as mobility or inflammation due to compromised periodontal tissues are not considered suitable abutments. In cases where a tooth has poor alveolar support, extraction followed by utilizing an adjacent, more stable tooth for support often yields better long-term outcomes.<\/p>\r\n\r\n<h2 data-start=\"775\" data-end=\"1375\"><strong data-start=\"775\" data-end=\"798\">Crown-to-root ratio<\/strong><\/h2>\r\n<p class=\"\" data-start=\"775\" data-end=\"1375\">An ideal crown-to-root ratio of 1:2 provides favorable conditions for mechanical stability and functional support. The crown's size and its axial alignment with the root allow for effective distribution of axial forces and proper placement of clasp components. A 1:1 ratio offers reduced support and stability, while a 2:1 ratio\u2014where the crown is longer than the root\u2014is considered inadequate. In such cases, the unfavorable crown angulation and its disproportion to the root and surrounding periodontal tissues compromise the transmission of occlusal forces (Figure 1-26).<\/p>\r\n\r\n\r\n[caption id=\"attachment_55\" align=\"alignnone\" width=\"300\"]<img class=\"wp-image-55 size-medium\" src=\"http:\/\/ekitap.ankara.edu.tr\/dentures\/wp-content\/uploads\/sites\/29\/2023\/05\/Sekil1.26-300x156.jpg\" alt=\"Figure 1-26. Crown-to-root ratio.a) 1:2. b) 1:1. c) 2:1. As the alveolar bone resorbs from the 1st line to the 2nd line level, the crown-to-root ratio increases.\" width=\"300\" height=\"156\" \/> <strong>Figure 1-26.<\/strong> Crown-to-root ratio. <strong>a)<\/strong>1:2. <strong>b)<\/strong> 1:1. <strong>c)<\/strong> 2:1. As the alveolar bone resorbs from the 1st line to the 2nd line level, the crown-to-root ratio increases.[\/caption]\r\n<h2><strong>Crown and root morphology<\/strong><\/h2>\r\nWhile teeth with cylindrical and thin-pointed roots have very low resistance to torque-type stresses, teeth with a large root surface within the bone exhibit the best tooth support properties (Figure 1-27).\r\n\r\n[caption id=\"attachment_56\" align=\"alignnone\" width=\"286\"]<img class=\"wp-image-56 size-medium\" src=\"http:\/\/ekitap.ankara.edu.tr\/dentures\/wp-content\/uploads\/sites\/29\/2025\/04\/Sekil1.27-286x300.jpg\" alt=\"Figure 1-27. Crown-root morphology.(A) As the roots of teeth exhibit a cylindrical or increasingly narrow structure, their resistance to forces weakens. (B) As the surface area of \u200b\u200bthe root within the bone increases, its support potential increases.\" width=\"286\" height=\"300\" \/> <strong>Figure 1-27.<\/strong> Crown-root morphology. (A) As the roots of teeth exhibit a cylindrical or increasingly narrow structure, their resistance to forces weakens. (B) As the surface area of \u200b\u200bthe root within the bone increases, its support potential increases.[\/caption]\r\n<h2><strong>Position within the dental arch<\/strong><\/h2>\r\nThe position of abutment teeth within the dental arch is critically important for managing functional stresses and preventing potential damage to the supporting structures. Teeth that are misaligned, partially erupted, or have drifted or tilted due to previous tooth loss or other factors are generally less capable of effectively absorbing prosthetic forces. Therefore, unless absolutely necessary, such teeth should not be selected as abutments for removable partial dentures (Figure 1-28).\r\n\r\n[caption id=\"attachment_57\" align=\"alignnone\" width=\"300\"]<img class=\"wp-image-57 size-medium\" src=\"https:\/\/ekitap.ankara.edu.tr\/wp-content\/uploads\/sites\/29\/2025\/04\/Sekil1.28-300x195.jpg\" alt=\"Figure 1-28. Tooth migrations causing changes in occlusion.\" width=\"300\" height=\"195\" \/> <strong>Figure 1-28. <\/strong>Tooth migrations causing changes in occlusion.[\/caption]\r\n\r\nHowever, in cases where the use of such teeth as abutments is unavoidable, careful evaluation of prosthetic planning criteria is essential to ensure that stresses are either minimized or adequately controlled.\r\n<h2><strong>Opposing occlusion<\/strong><\/h2>\r\nThe type of opposing occlusion and the number of teeth present in the opposing arch significantly influence the selection of abutment teeth. In individuals with natural dentition, occlusal forces can be up to ten times greater than those in patients wearing complete dentures. As a result, an abutment tooth used against a complete denture will be subjected to considerably less stress compared to one opposing natural dentition. Similarly, in cases where mutually protected occlusion is present, the teeth that bear the occlusal load are exposed to greater functional stress. Therefore, the supportive characteristics of these abutment teeth must be carefully evaluated during treatment planning.","rendered":"<p>When determining teeth to serve as abutments for RPDs, their ability to resist functional stresses is a key consideration for ensuring controlled force transmission. The potential of a tooth to function as a reliable prosthetic abutment is assessed based on the following criteria:<\/p>\n<ul>\n<li>Periodontal health<\/li>\n<li>Crown-to-root ratio<\/li>\n<li>Crown and root morphology<\/li>\n<li>Position within the dental arch<\/li>\n<li>Opposing occlusion<\/li>\n<\/ul>\n<h2 data-start=\"93\" data-end=\"773\"><strong data-start=\"93\" data-end=\"115\">Periodontal health<\/strong><\/h2>\n<p class=\"\" data-start=\"93\" data-end=\"773\">In evaluating abutment teeth for removable partial dentures, both clinical and radiographic findings must be carefully assessed. Since the terminal abutment teeth are subject to increased stress compared to non-supporting teeth, the quality and quantity of their alveolar bone support are of critical importance. Teeth exhibiting signs of periodontal lesions, infection, or clinical symptoms such as mobility or inflammation due to compromised periodontal tissues are not considered suitable abutments. In cases where a tooth has poor alveolar support, extraction followed by utilizing an adjacent, more stable tooth for support often yields better long-term outcomes.<\/p>\n<h2 data-start=\"775\" data-end=\"1375\"><strong data-start=\"775\" data-end=\"798\">Crown-to-root ratio<\/strong><\/h2>\n<p class=\"\" data-start=\"775\" data-end=\"1375\">An ideal crown-to-root ratio of 1:2 provides favorable conditions for mechanical stability and functional support. The crown&#8217;s size and its axial alignment with the root allow for effective distribution of axial forces and proper placement of clasp components. A 1:1 ratio offers reduced support and stability, while a 2:1 ratio\u2014where the crown is longer than the root\u2014is considered inadequate. In such cases, the unfavorable crown angulation and its disproportion to the root and surrounding periodontal tissues compromise the transmission of occlusal forces (Figure 1-26).<\/p>\n<figure id=\"attachment_55\" aria-describedby=\"caption-attachment-55\" style=\"width: 300px\" class=\"wp-caption alignnone\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-55 size-medium\" src=\"http:\/\/ekitap.ankara.edu.tr\/dentures\/wp-content\/uploads\/sites\/29\/2023\/05\/Sekil1.26-300x156.jpg\" alt=\"Figure 1-26. Crown-to-root ratio.a) 1:2. b) 1:1. c) 2:1. As the alveolar bone resorbs from the 1st line to the 2nd line level, the crown-to-root ratio increases.\" width=\"300\" height=\"156\" srcset=\"https:\/\/ekitap.ankara.edu.tr\/dentures\/wp-content\/uploads\/sites\/29\/2023\/05\/Sekil1.26-300x156.jpg 300w, https:\/\/ekitap.ankara.edu.tr\/dentures\/wp-content\/uploads\/sites\/29\/2023\/05\/Sekil1.26-65x34.jpg 65w, https:\/\/ekitap.ankara.edu.tr\/dentures\/wp-content\/uploads\/sites\/29\/2023\/05\/Sekil1.26-225x117.jpg 225w, https:\/\/ekitap.ankara.edu.tr\/dentures\/wp-content\/uploads\/sites\/29\/2023\/05\/Sekil1.26-350x182.jpg 350w, https:\/\/ekitap.ankara.edu.tr\/dentures\/wp-content\/uploads\/sites\/29\/2023\/05\/Sekil1.26.jpg 384w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><figcaption id=\"caption-attachment-55\" class=\"wp-caption-text\"><strong>Figure 1-26.<\/strong> Crown-to-root ratio. <strong>a)<\/strong>1:2. <strong>b)<\/strong> 1:1. <strong>c)<\/strong> 2:1. As the alveolar bone resorbs from the 1st line to the 2nd line level, the crown-to-root ratio increases.<\/figcaption><\/figure>\n<h2><strong>Crown and root morphology<\/strong><\/h2>\n<p>While teeth with cylindrical and thin-pointed roots have very low resistance to torque-type stresses, teeth with a large root surface within the bone exhibit the best tooth support properties (Figure 1-27).<\/p>\n<figure id=\"attachment_56\" aria-describedby=\"caption-attachment-56\" style=\"width: 286px\" class=\"wp-caption alignnone\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-56 size-medium\" src=\"http:\/\/ekitap.ankara.edu.tr\/dentures\/wp-content\/uploads\/sites\/29\/2025\/04\/Sekil1.27-286x300.jpg\" alt=\"Figure 1-27. Crown-root morphology.(A) As the roots of teeth exhibit a cylindrical or increasingly narrow structure, their resistance to forces weakens. (B) As the surface area of \u200b\u200bthe root within the bone increases, its support potential increases.\" width=\"286\" height=\"300\" srcset=\"https:\/\/ekitap.ankara.edu.tr\/dentures\/wp-content\/uploads\/sites\/29\/2025\/04\/Sekil1.27-286x300.jpg 286w, https:\/\/ekitap.ankara.edu.tr\/dentures\/wp-content\/uploads\/sites\/29\/2025\/04\/Sekil1.27-65x68.jpg 65w, https:\/\/ekitap.ankara.edu.tr\/dentures\/wp-content\/uploads\/sites\/29\/2025\/04\/Sekil1.27-225x236.jpg 225w, https:\/\/ekitap.ankara.edu.tr\/dentures\/wp-content\/uploads\/sites\/29\/2025\/04\/Sekil1.27-350x367.jpg 350w, https:\/\/ekitap.ankara.edu.tr\/dentures\/wp-content\/uploads\/sites\/29\/2025\/04\/Sekil1.27.jpg 412w\" sizes=\"auto, (max-width: 286px) 100vw, 286px\" \/><figcaption id=\"caption-attachment-56\" class=\"wp-caption-text\"><strong>Figure 1-27.<\/strong> Crown-root morphology. (A) As the roots of teeth exhibit a cylindrical or increasingly narrow structure, their resistance to forces weakens. (B) As the surface area of \u200b\u200bthe root within the bone increases, its support potential increases.<\/figcaption><\/figure>\n<h2><strong>Position within the dental arch<\/strong><\/h2>\n<p>The position of abutment teeth within the dental arch is critically important for managing functional stresses and preventing potential damage to the supporting structures. Teeth that are misaligned, partially erupted, or have drifted or tilted due to previous tooth loss or other factors are generally less capable of effectively absorbing prosthetic forces. Therefore, unless absolutely necessary, such teeth should not be selected as abutments for removable partial dentures (Figure 1-28).<\/p>\n<figure id=\"attachment_57\" aria-describedby=\"caption-attachment-57\" style=\"width: 300px\" class=\"wp-caption alignnone\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-57 size-medium\" src=\"https:\/\/ekitap.ankara.edu.tr\/wp-content\/uploads\/sites\/29\/2025\/04\/Sekil1.28-300x195.jpg\" alt=\"Figure 1-28. Tooth migrations causing changes in occlusion.\" width=\"300\" height=\"195\" srcset=\"https:\/\/ekitap.ankara.edu.tr\/dentures\/wp-content\/uploads\/sites\/29\/2025\/04\/Sekil1.28-300x195.jpg 300w, https:\/\/ekitap.ankara.edu.tr\/dentures\/wp-content\/uploads\/sites\/29\/2025\/04\/Sekil1.28-65x42.jpg 65w, https:\/\/ekitap.ankara.edu.tr\/dentures\/wp-content\/uploads\/sites\/29\/2025\/04\/Sekil1.28-225x147.jpg 225w, https:\/\/ekitap.ankara.edu.tr\/dentures\/wp-content\/uploads\/sites\/29\/2025\/04\/Sekil1.28-350x228.jpg 350w, https:\/\/ekitap.ankara.edu.tr\/dentures\/wp-content\/uploads\/sites\/29\/2025\/04\/Sekil1.28.jpg 413w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><figcaption id=\"caption-attachment-57\" class=\"wp-caption-text\"><strong>Figure 1-28. <\/strong>Tooth migrations causing changes in occlusion.<\/figcaption><\/figure>\n<p>However, in cases where the use of such teeth as abutments is unavoidable, careful evaluation of prosthetic planning criteria is essential to ensure that stresses are either minimized or adequately controlled.<\/p>\n<h2><strong>Opposing occlusion<\/strong><\/h2>\n<p>The type of opposing occlusion and the number of teeth present in the opposing arch significantly influence the selection of abutment teeth. In individuals with natural dentition, occlusal forces can be up to ten times greater than those in patients wearing complete dentures. As a result, an abutment tooth used against a complete denture will be subjected to considerably less stress compared to one opposing natural dentition. Similarly, in cases where mutually protected occlusion is present, the teeth that bear the occlusal load are exposed to greater functional stress. Therefore, the supportive characteristics of these abutment teeth must be carefully evaluated during treatment planning.<\/p>\n","protected":false},"author":3,"menu_order":8,"template":"","meta":{"_monsterinsights_skip_tracking":false,"_monsterinsights_sitenote_active":false,"_monsterinsights_sitenote_note":"","_monsterinsights_sitenote_category":0,"_uf_show_specific_survey":0,"_uf_disable_surveys":false,"pb_show_title":"on","pb_short_title":"","pb_subtitle":"","pb_authors":[],"pb_section_license":""},"chapter-type":[],"contributor":[],"license":[],"class_list":["post-58","chapter","type-chapter","status-publish","hentry"],"part":21,"_links":{"self":[{"href":"https:\/\/ekitap.ankara.edu.tr\/dentures\/wp-json\/pressbooks\/v2\/chapters\/58","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/ekitap.ankara.edu.tr\/dentures\/wp-json\/pressbooks\/v2\/chapters"}],"about":[{"href":"https:\/\/ekitap.ankara.edu.tr\/dentures\/wp-json\/wp\/v2\/types\/chapter"}],"author":[{"embeddable":true,"href":"https:\/\/ekitap.ankara.edu.tr\/dentures\/wp-json\/wp\/v2\/users\/3"}],"version-history":[{"count":15,"href":"https:\/\/ekitap.ankara.edu.tr\/dentures\/wp-json\/pressbooks\/v2\/chapters\/58\/revisions"}],"predecessor-version":[{"id":1916,"href":"https:\/\/ekitap.ankara.edu.tr\/dentures\/wp-json\/pressbooks\/v2\/chapters\/58\/revisions\/1916"}],"part":[{"href":"https:\/\/ekitap.ankara.edu.tr\/dentures\/wp-json\/pressbooks\/v2\/parts\/21"}],"metadata":[{"href":"https:\/\/ekitap.ankara.edu.tr\/dentures\/wp-json\/pressbooks\/v2\/chapters\/58\/metadata\/"}],"wp:attachment":[{"href":"https:\/\/ekitap.ankara.edu.tr\/dentures\/wp-json\/wp\/v2\/media?parent=58"}],"wp:term":[{"taxonomy":"chapter-type","embeddable":true,"href":"https:\/\/ekitap.ankara.edu.tr\/dentures\/wp-json\/pressbooks\/v2\/chapter-type?post=58"},{"taxonomy":"contributor","embeddable":true,"href":"https:\/\/ekitap.ankara.edu.tr\/dentures\/wp-json\/wp\/v2\/contributor?post=58"},{"taxonomy":"license","embeddable":true,"href":"https:\/\/ekitap.ankara.edu.tr\/dentures\/wp-json\/wp\/v2\/license?post=58"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}