The maxillary central incisor (dens incisivus me-dialis) (Figs 4-19 to 4-21) is the largest incisor tooth, having a rectangular to rhomboid, triangular, or oval vestibular surface, which can harmonize with the shape of the face.
Its average dimensions are:
- Crown width (mesiodistal): 8.5 mm
- Crown depth (labiolingual): 7.0 mm
- Crown length: 11.5 mm
- Total apicocoronal length: 25.0 mm
Its root forms an elongated cone, is straight from an approximal view, and is slightly bent distally from a labial view (root characteristic). The strong root makes it usable as an abutment tooth or suitable for placement of a post crown.
The labial surface (see Fig 4-19a) is almost rectangular and tapers cervically. The mesial edge looks rather straight, whereas the distal edge is curved. The labial surface has a vertical and horizontal curvature characteristic as well as a pronounced angle characteristic. The surface is defined by two marginal ridges and a medial ridge, which are separated by two vertical grooves. When the teeth are freshly erupted, these ridges make the incisal margin appear to have three lobes. This form is lost through abrasion. The distal approximal edge is slightly concave to the cervix and becomes an evenly curved cervical margin. A few slightly pronounced cervical grooves run almost parallel to the cervical margin.
The lingual surface (see Fig 4-19b) resembles the labial surface but is smaller and narrower and tapers more sharply, especially in the cervical area. Two marginal ridges run from the incisal edge cervically, then merge in the apical third of the surface to form the dental tubercle. The marginal ridges outline the concave surface like the edges of a shovel. Differently shaped medial ridges emerge from the tubercle. Depending on the concavity of the lingual surface and the number of enamel ridges, the tubercle can be divided into two tubercles, for example, or the margins may form a partially covered canal.
The mesial approximal surface (see Fig 4-19c) has a triangular shape, with the apex at the incisal edge and the baseline at the cervix; the functional chisel shape of the incisor can be seen. The cervical line curves considerably in an incisal direction. The surface itself is tapered toward the neck of the tooth. The vertical curvature of the labial surface contour and the prominent dental tubercle, whose curvature is greatest at the neck, can be clearly seen. The mesial approximal surface is larger than the distal surface.
The incisal view (see Fig 4-19d) shows the features of the other surfaces described above: The curvature characteristic can be seen, and the distal aspect of the surfaces tapers slightly, while the mesial aspect is prominently curved.The cusplike thickening of the dental tubercle can be clearly seen, as can the marginal ridges and the medial ridge. Figure 4-19d shows both the mesial and the distal contact points as the widest convexity of the approximal surfaces.
The maxillary lateral incisor (dens incisivus lateralis) (Figs 4-22 and 4-23) has the same basic shape as the central incisor but is significantly smaller.
Its average dimensions are:
- Crown width (mesiodistal): 6.5 mm
- Crown depth (labiolingual): 6.0 mm
- Crown length: 10.0 mm
- Total apicocoronal length: 23.0 mm
Variations in form and size can be seen with this tooth. It is one of the teeth that is in the process of regression; it may sometimes be entirely absent. It can resemble a primary tooth; even pointed, peg, and pin shapes are possible. The dental tubercle may be developed into a separate lingual tubercle. The lateral incisor is rather shorter than the central incisor, but it is inclined mesially like the central incisor. It has a greater vestibular inclination than the central incisor. The second incisor is single-rooted with a distinctive root characteristic: The root is flattened in the mesiodistal direction and poorly developed with lateral longitudinal fissures, and the root canal
is often deformed.
The labial surface is the same as that of the central incisor but smaller and more delicate with rounded edges and more pronounced curvature and angle characteristics.
The lingual surface has very pronounced marginal ridges and a distinctive tubercle.The surface often appears concave and undercut, especially if the tubercle is very strongly developed and the surface is rather covered over. This is where caries often develops.
The approximal surfaces are markedly concave below the contact points, so that the labial surface appears strikingly triangular. Form variations in the lateral incisors are particularly noticeable in this view.
The incisal view shows a very rounded incisal margin, and all the curvatures are clearly visible.
Meno ya msingi ya maxillary (Dens incisor medialis) ni kubwa zaidi ya meno ya msingi, na ina rectangular kwa rhomboid, triangular, au oval vestibular uso, ambayo inaweza kuendana na sura ya uso. Urefu wa kipenyo: 8.5mm; Labiolingual: 7.0mm; Urefu wa kipenyo: 11.5mm; Urefu wa jumla wa apicoronal: 25.0mm; Mizizi yake huunda koni ya muda mrefu, ni moja kwa moja kutoka kwa mtazamo wa karibu, na ni kidogo bent distally kutoka kwa mtazamo wa labial. Mizizi yenye nguvu hufanya iweze kutumiwa kama jino la msingi au inafaa kwa kuwekwa kwa taji la post. Labial (tazama Picha 4-19a) ni karibu rectangular na tapers cervically. Upande wa katikati wa mwili unaonekana kuwa wa moja kwa moja, ilhali upande wa mbali wa mwili una umbo la mviringo. Labial uso ina wima na usawa curvature tabia kama vile sifa ya pembe dhahiri. Uso ni maalum na mbili marginal ridges na medial ridges, ambayo ni kutengwa na mbili wima grooves. Meno yanapochomoza, miamba hiyo hufanya ukingo wa msumari uonekane kuwa na vipande vitatu. Fomu hii hupoteza kupitia msuguano. ukingo wa distal approximimal ni kidogo concave kwa cervix na inakuwa usawa curved cervical margin. Vipande vichache vya shingo ya tumbo la uzazi vinaonekana waziwazi na vinaelekea karibu na ukingo wa shingo ya tumbo la uzazi. Lingual uso (tazama Picha 4-19b) ni sawa na labial uso lakini ni ndogo na nyembamba na tapers zaidi kwa kasi, hasa katika eneo la shingo ya tumbo. Matofali mawili ya pembeni huanzia ukingo wa incisal cervically, kisha huungana katika theluthi ya apical ya uso kuunda tubercle ya meno. Matofali ya pembeni huonyesha uso wenye umbo la mviringo kama kingo za jembe. Matofali ya katikati yenye umbo tofauti hutoka kwenye kibofu hicho. Kulingana na concavity ya uso wa ulimi na idadi ya ridge enamel, tubercles inaweza kugawanywa katika tubercles mbili, kwa mfano, au kingo inaweza kuunda sehemu ya kufichwa mfereji. Mfano wa msalaba wa msalaba wa msalaba (Figure 4-19b) una umbo la pembetatu, na kilele chake ni kwenye ukingo wa incisor na msingi ni kwenye shingo ya uterasi; umbo la msalaba wa msalaba linaweza kuonekana. Mstari wa shingo ya tumbo la uzazi curves kwa kiasi kikubwa katika mwelekeo incisal. Sehemu ya juu ya jino hilo huelekea kwenye shingo ya jino hilo. Mzunguko wa wima wa uso wa labial na tubercle ya meno inayoonekana, ambayo mzunguko wake ni mkubwa zaidi kwenye shingo, unaweza kuonekana wazi. Uso wa karibu wa mesial ni mkubwa kuliko uso wa mbali. Mtazamo wa incisor (tazama Picha 4-19d) unaonyesha sifa za nyuso zingine zilizoelezwa hapo juu: sifa ya curvature inaweza kuonekana, na sura ya distal ya nyuso hupungua kidogo, wakati sura ya mesial ni curved sana. Picha ya 4 inaonyesha sehemu ya kati ya mstari wa 4 na mstari wa mbali wa mstari wa mstari wa mstari wa mstari wa mstari wa mstari wa mstari wa mstari wa mstari wa mstari wa mstari wa mstari wa mstari wa mstari wa mstari wa mstari wa mstari wa mstari wa mstari wa mstari wa mstari wa mstari. Meno ya chini ya maxillary (Dens incisor lateralis) ni sehemu ya chini ya mshipa wa juu wa maxillary. Urefu wa kawaida ni: - Upana wa taji (mesiodistal): 6.5mm; - Urefu wa taji (labiolingual): 6.0mm; - Urefu wa taji: 10.0mm; - Urefu wa jumla wa apicocoronal: 23.0mm. Ni mojawapo ya meno ambayo yanarudi nyuma; nyakati nyingine huenda yakakatika kabisa. Inaweza kufanana na jino la msingi; hata umbo la ncha, ncha, na ncha linaweza kutumiwa. Kibofu cha meno chaweza kugeuka kuwa kibofu cha lugha tofauti. Mdomo wa upande ni mfupi kuliko ule wa katikati, lakini umeelekezwa upande wa katikati kama ule wa katikati. Ina mwelekeo mkubwa zaidi wa vestibular kuliko jino la kati la kukata. Meno ya pili ni moja-mzizi na sifa ya msingi wa kipekee: mzizi ni flattened katika mwelekeo mesiodistal na chini ya maendeleo na lateral longitudinal fissures, na mfereji mzizi ni mara nyingi deformed. Labial uso ni sawa na ile ya incisor kati lakini ndogo na nyembamba zaidi na kingo mviringo na zaidi ya kutokeza curvature na pembe sifa. Uso wa ulimi una mipaka ya wazi na tubercles ya kipekee.Uso mara nyingi huonekana kuwa concave na undercut, hasa kama tubercles ni sana maendeleo na uso ni badala kufunikwa juu. Mara nyingi ugonjwa huo huanza kutokea. Vipande vya karibu ni concave sana chini ya pointi ya mawasiliano, hivyo kwamba uso labial inaonekana strikingly pembetatu. Tofauti za umbo katika meno ya upande ni hasa dhahiri katika mtazamo huu. Mtazamo incisal inaonyesha margin incisal sana mviringo, na curvatures wote ni wazi inayoonekana.