Aesthetic Analysis of an Implant-Supported Denture at the Cleft Area

Abstract

Objective

To evaluate the aesthetics of an implant-supported denture at the cleft area, comparing the peri-implant tissues and prosthetic crown with the contralateral tooth.

Settings

Hospital for Rehabilitation of Craniofacial Anomalies, Bauru, São Paolo, Brazil.

Patients

A total of 39 individuals of both genders, with complete unilateral cleft lip and palate, who received secondary alveolar bone graft and were rehabilitated with single implant-supported dentures at the area of the missing maxillary lateral incisor after completion of orthodontic treatment.

Interventions

The following parameters were analyzed in follow-up sessions: length and width of prosthetic crown and contralateral tooth, characteristics of implants, filling of interproximal space by the papilla, and smile height of the patients.

Results

The implant-supported prosthetic crowns were longer than the contralateral tooth (p < .001). Among the 78 papillae analyzed, 29 (37.17%) received a score of 3; 32 (41.02%) papillae had a score of 2; and 17 (21.79%) received a score of 1. Concerning the smile height, among the 39 patients analyzed, 23 (56.41%) had a medium smile, 15 (38.46%) had a high smile, and two (5.12%) presented a low smile.

Conclusion

The use of dental implants to rehabilitate the edentulous cleft area is an excellent option. However, adequate evaluation of the bone quantity and quality, positioning and shape of adjacent teeth, smile height, and patient expectations should be considered to achieve success and avoid aesthetic deformities such as elongated teeth and absence of gingival papillae.

Keywords

aesthetics cleft lip and palate dental implants

Individuals with cleft lip and palate undergo several surgical procedures at the orofacial region to correct facial deformities and improve function (Marsh, 1990). Facial and oral aesthetics are desired by these individuals, given that appearance is a critical factor for social development (Tobiasen, 1994). The smile is one of the most important facial expressions and means of nonverbal communication, playing an important role in interpersonal relationships. The essence of a smile involves the relationship among three basic primary components, namely the teeth, lip architecture, and gingival tissue. Any disturbance or imbalance in the relationship among these components calls attention, breaking the aesthetics principles (Garber and Salama, 1996; An et al., 2009).

Based on this concept, the final objective of restorative dental treatment is currently to achieve the balance between the “white” and “pink” aesthetics (tooth structures and periodontal tissue, respectively) in areas with aesthetic importance (Blatz et al., 1999). In the case of individuals with clefts, the third aesthetic element, namely the lip architecture, would be under the responsibility of the surgeon.

The smile line is one of the most important factors contributing to a pleasant smile. According to the position of the upper lip, the smile may be classified as high, characterized by total exposure of the cervico-incisal length of the maxillary anterior teeth and an area of keratinized gingiva; medium, when the smile reveals 75% to 100% of maxillary anterior teeth and interproximal gingiva; and low, when less than 75% of maxillary anterior teeth are exposed during smiling (Tjan et al., 1984).

The absence of a tooth or alterations in tooth shape and color may considerably alter the white aesthetics. The edentulism at the cleft area caused by hypodontia/extraction of the maxillary lateral incisor in 48% of cases may be conventionally solved by orthodontic therapy with movement of canines and posterior teeth to the grafted cleft area (Bergland et al., 1986); maintenance of supernumerary reconstructed teeth after secondary alveolar bone graft (SABG); or even fixed, adhesive, or removable partial dentures in case of failure of SABG or when the patients search for treatment at older ages, precluding the rehabilitation of the alveolar cleft by bone grafting (Kearns et al., 1997; Silva Filho et al., 2000; Kinzer and Kokich, 2005a, 2005b).

More recently, treatment of the edentulous cleft area with endosseous implants has become an option to replace the prosthetic preparation of intact teeth adjacent to the edentulous space, which is necessary for fabrication of conventional fixed partial dentures. The long-term effectiveness of implant-supported dentures has also been clearly demonstrated in several studies (Jemt and Pettersson, 1993; Mayer et al., 2002; Sullivan, 2003; Covani et al., 2004), with high success rates (Matsui et al., 2007; de Barros Ferreira et al., 2010).

The increased aesthetic demand requires a harmonious gingival contour of the prosthetic rehabilitation with the adjacent tooth or implant and the contralateral tooth, with intact interproximal papilla, concave contour, and satisfactory color of the gingival tissue (Woo, 1991; Khoury and Happe, 2000).

The great challenge now is to achieve an ideal relationship between the prosthetic crown and surrounding tissues, knowing that a well-planned and well-performed ceramic restoration may closely resemble any tooth. However, biological alterations such as local bone deficiency may contribute to an elongated prosthetic crown with a different shape compared with the contralateral tooth (Chang et al., 1999; Regis and Duarte, 2007).

This study evaluated the aesthetics of an implant-supported denture at the cleft area, comparing the peri-implant tissues and prosthetic crown with the contralateral tooth.

Materials and Methods

The sample included 39 individuals, of both genders, with complete unilateral cleft lip and palate, who received a secondary alveolar bone graft and were rehabilitated with a single implant-supported denture at the area of the missing maxillary lateral incisor after completion of orthodontic treatment at the Hospital for Rehabilitation of Craniofacial Anomalies, University of São Paulo (HRCA/USP), and attended the Implantology department for treatment in the years 2008 and 2009.

The exclusion criteria comprised individuals with congenital anomalies and/or systemic alterations; those who were pregnant, used anticonvulsant drugs, and/or smoked; and patients with hyperplastic gingiva because these factors might alter the clinical parameters of the peri-implant tissue evaluated in this study.

All individuals were informed about the study and signed an informed consent form agreeing to participate. This study was approved by the institutional review board of HRCA/USP (n. 399/2008).

The following parameters were analyzed in follow-up sessions routinely scheduled at the hospital for maintenance of oral rehabilitation and oral health: type of smile, length (distance between the upper gingival margin and center of incisal edge) and width (distance between upper gingival margin and center of incisal edge) of the prosthetic crown and contralateral tooth (Fig. 1), and characteristics of the implants used.

Figure 1

Scheme representing the measurements obtained on the clinical crown of the control tooth and implant-supported crown. The cervico-incisal length or distance is represented by line a-b, and the mesiodistal width or distance is represented by line c-d.

Filling of the interproximal space by the gingival papillae was analyzed as suggested by Jemt (1997): score 0 (absence of gingival papilla); score 1 (less than half of the proximal space was filled); score 2 (more than half of the interproximal space had been filled by the papilla, yet without complete filling), and score 3 (complete filling of the interproximal space). Score 4 was not used because hyperplastic papillae were excluded from the study (Fig. 2).

Figure 2

Images of prosthetic crowns at the region of the maxillary lateral incisor. At the left, a prosthetic crown of adequate size, well-adapted gingival margin, and complete filling of the interproximal space by the gingival papilla (score 3); at the center, prosthetic crown with adequate shape and filling of at least half of the interproximal space by the gingival papilla (score 2); at the right, prosthetic crown with elongated shape and filling of less than half of the interproximal space by the gingival papilla (score 1).

By analysis of digital photographs and taking the upper lip position as reference, the spontaneous smile of individuals was classified as high (Fig. 3a), medium (Fig. 3b), and low (Fig. 3c) (Tjan et al., 1984).

Figure 3

A: High smile. B: Medium smile. C: Low smile.

The results were analyzed by descriptive statistics, and the Student's t test was used to correlate the variables at a significance level of 5%.

Results

Of the 39 individuals studied, 21 were women and 18 were men; all had unilateral cleft lip, alveolus, and palate; ages ranged from 19 to 23 years. The mean follow-up period of the single implant-supported denture was 42 months after placement. There was no statistically significant difference between cleft side and gender (p = .327), which demonstrated the homogeneity of the sample.

The endosseous implants placed at the region of maxillary lateral incisor had different diameters and lengths according to the local bone availability. There was greater frequency of implants with a diameter of 3.3 and 3.75 mm and a length of 11 and 13 mm (Table 1).

Table 1

Distribution (n) of Implants Placed at the Region of Maxillary Lateral Incisor According to the Diameter (mm) and Length (mm)

	Length (mm)
Diameter (mm)	8	9	10	11	13	15	17	Total
3.3	0	0	1	6	6	4	0	17
3.75	0	1	1	8	5	3	1	19
4.0	1	0	0	1	0	1	0	3
Total	1	1	2	15	11	8	1	39

To allow the placement of an implant at the cleft area, 19 (48.72%) individuals required a complementary bone graft, which was harvested from the mandibular ramus in all cases to increase the alveolar ridge thickness. The mean length and width of prosthetic crowns and crowns of contralateral teeth and their differences are presented in Table 2, as are as the differences between the means and comparison between the implant-supported prosthetic crown and the contralateral tooth crown. The prosthetic crown with the shortest length was 7.67 mm and with the longest, 12.08 mm. There was a statistically significant difference between the mean lengths of crowns and teeth (p < .01). Concerning the difference between widths, in 82% there was a difference of 0 to 1 mm and in 18% of 1.01 to 2.00 mm (Table 2).

Table 2

Mean Dimensions of Crown of Contralateral Tooth and Prosthetic Crown

Variable	Prosthetic Crown	Contralateral Tooth Crown	Difference Between Means	p
Length (mm)	9.85	8.56	1.28	<.001^*
Width (mm)	7.07	7.01	0.06	.61

p<0.05 (paired t test).

The interproximal papillae were scored as proposed by Jemt (1997). Among the 78 papillae analyzed, 29 (37.17%) received score 3; 32 (41.02%) papillae had score 2; and 17 (21.79%) papillae received score 1.

Table 3 demonstrates the comparison between gingival papillae scores and the other variables (implant diameter and complementary bone grafting). The means were very close, suggesting that there was no direct influence of these variables on the score of papillae.

Table 3

Mean Scores of Interproximal Papillae According to the Related Variables

Interproximal Papillae	Variables
	General Mean	Implant Diameter (mm)		Complementary Bone Grafting
	General Mean	3.3	4.1	With	Without
Implant/maxillary lateral incisor	2.12	2.27	2.00	2.00	2.25
Implant/maxillary canine	2.2	2.27	2.14	2.05	2.35

With regard to the smile line, among the 39 patients analyzed, 23 (56.41%) had a medium smile, 15 (38.46%) had a high smile, and two (5.12%) had a low smile. There was a tendency toward smaller exposure of teeth and periodontium on spontaneous smiling at the cleft side (Fig. 4).

Figure 4

A: Implant-supported denture with impaired aesthetics. B: Smile line of the patient. The aesthetic imperfections related to inadequate implant positioning, elongated prosthetic crown, deficient interproximal papilla, and exposure of the implant platform are hidden by the low smile of the patient.

Discussion

The smile is a universal expression and one of the means to express human feelings. The achievement of pleasant aesthetics in oral rehabilitation should consider three aspects: smile height (position of upper lip), teeth or dentures, and gingival tissue. In the present study, 61.53% of individuals presented a medium or low smile, which may have contributed to the satisfaction of these individuals after rehabilitation. Both types of smile may have contributed to reduce the exposure of imperfections in white and pink aesthetics because in most cases only the gingival papillae appeared during smiling (Tjan et al., 1984; Yoon et al., 1992) (Fig. 3).

In individuals with clefts affecting the alveolar ridge, hypodontia of the maxillary lateral incisor at the cleft side is common (45% of cases), which seems to be more prevalent according to the severity of the cleft (Pena et al., 2009).

The rehabilitation of the cleft area (i.e., replacement of the missing tooth, usually the permanent maxillary lateral incisor) may be performed by several options, including rehabilitation with prostheses (Oosterkamp et al., 2010). The preparation of intact teeth for placement of fixed partial dentures has been widely discussed, especially after the advent of endosseous implants (Kearns et al., 1997; Kramer et al., 2005; Sawaki et al., 2008; Vecchiatini et al., 2009).

Since the first report in 1991, endosseous implants have been used as an option for rehabilitation of patients with clefts with a grafted alveolar ridge, and most studies reveal implant survival above 90% (Verdi et al., 1991; Ronchi et al., 1995; Kearns et al., 1997; Takahashi et al., 1997; Fukuda et al., 1998; Jensen et al., 1998; Jansma et al., 1999; Cune et al., 2004; Kramer et al., 2005; de Barros Ferreira et al., 2010). Selection of implant diameter and length depends on the bone availability at the receptor site (Kramer et al., 2005; Matsui et al., 2007).

The implant placement should be performed after completion of growth. Considering the long time interval between the secondary alveolar bone graft and implant placement, a complementary bone graft is usually necessary to reestablish the lost local anatomy, especially in thickness, due to the bone remodeling occurring during this period (Kearns et al., 1997; Sawaki et al., 2008).

The complementary bone graft to increase thickness may be performed with biomaterials or particulate or block autogenous bone graft, usually harvested from the mandibular ramus or symphysis (Sawaki et al., 2008; Vecchiatini et al., 2009). Though present in smaller quantity, the bone harvested from intraoral regions is enough for grafting at the region of the maxillary lateral incisor. Inadequate bone width may lead to implant placement in a nonideal position, which may impair the final aesthetics of the implant-supported denture (Cune et al., 2004).

The three-dimensional positioning of the implant should be considered at treatment onset; the correct position should consider the bone height and thickness available at the area to be rehabilitated. The height of bone tissue at the receptor site of the implant determines the vertical dimension of the prosthetic crown (i.e., the crown length) (Cune et al., 2004; Lalo et al., 2007). Ideally, the implant should be placed at 1 to 3 mm from the cementoenamel junction of adjacent teeth. The alveolar ridge thickness should also be considered for ideal positioning of the implant (it should be placed at the cingulum region). The extent of the edentulous space also influences the final aesthetics of the prosthetic crown because wide spaces lead to wide crowns and reduced spaces lead to narrow crowns (Blatz et al., 1999; Cune et al., 2004; Lalo et al., 2007).

In the present study, 48.72% of individuals received intraoral complementary bone graft before implant placement at the area of the maxillary lateral incisor. In the other 51.28%, the bone quantity remaining from the secondary alveolar bone graft allowed implant placement without the complementary graft. There was no direct relationship between the age at accomplishment of secondary alveolar bone graft and the complementary graft; that is, patients submitted to secondary alveolar bone graft in adulthood (20 years) also required the complementary bone graft, even if the time elapsed between both procedures was only 9 months. One possible explanation for this fact may be that the success rate of the secondary alveolar bone graft was not analyzed.

When the accomplishment of a complementary bone graft was correlated to the diameter of the implants placed, no significant difference was observed. Even with the complementary bone graft, some patients presented insufficient bone quantity for placement of implants with 3.75 mm, which would be the standard dimension at the area of the maxillary lateral incisor.

The bone quantity available when the implants were placed also influenced the type of crown-implant connection and the length of the prosthetic crown. The dentures may be cemented or screwed. In this study, 34 (81.17%) were cemented and 6 (18.83%) were screwed on the implant head. The prosthetic crowns are usually cemented when implants are placed in a nonideal position due to inadequate bone thickness.

Concerning the length of the prosthetic crown and the crown of the contralateral incisor, in nearly all cases the prosthetic crowns had greater length than the contralateral tooth, similar to the report of Chang et al. (1999).

The width of the prosthetic crown is related to the space of the missing lateral incisor and adjacent teeth, which is determined by the orthodontic treatment. This study did not observe a statistically significant difference between the size of the prosthetic crown and the contralateral tooth, evidencing maintenance of adequate space by the previous orthodontic treatment.

Several factors are related to gingival aesthetics, including the gingival phenotype, concave contour, and interproximal papilla. The interproximal papilla is fundamental to protecting the periodontium, including the alveolar bone crest, acting as a biological barrier against external aggressors, protecting against food impaction, and maintaining the homeostatic balance. Additionally, its loss may lead to aesthetic and speech problems (Tarnow et al., 1992).

In addition to bone availability (height and thickness), the periodontal biotype, shape and contact point between restoration or dental crown, and positioning of the tooth or implant in the dental arch are significant for the location and quality of interproximal papillae (Chow and Wang, 2009), and consequently for the final aesthetics of the rehabilitative treatment and smile of the individual.

The alveolar ridge has been considered the “support base” of the gingival tissue. Several studies have demonstrated that when the distance between the bone crest and contact point between the teeth is smaller than or equal to 5 mm, there is great chance of complete filling of the interproximal space by gingival tissue (Choquet et al., 2001; Tarnow et al., 2003).

The shape of the tooth crown also seems important for the papilla formation. According to Kan et al. (2003), when the individual presents a short and square crown, the interproximal contact with adjacent teeth is greater and the amount of gingival papilla required to fill the space is smaller. The interproximal contact between teeth with triangular shape is usually more incisally located.

In the current study, 78% of papillae were present, filling at least half of the interproximal space. This would not be completely satisfactory if the patients presented a high smile. The implant diameter and accomplishment of the complementary bone graft did not influence the presence of papillae.

A high degree of satisfaction was reported by the patients after completion of rehabilitation of the area with an implant-supported dental prosthesis. Even though in some cases there was absence of papillae and difference in size and width between the prosthetic crown and contralateral tooth, these factors did not have a negative influence. Nearly all individuals presented a low smile line, thus precluding the observation of factors that might interfere with the smile aesthetics.

Conclusion

Dental rehabilitation at the cleft area with an implant-supported denture is an excellent option. However, adequate evaluation of the bone quantity and quality, position and shape of adjacent teeth, smile height, and patient expectations should be considered to achieve success and avoid aesthetic deformities such as elongated teeth and absence of gingival papillae.

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