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Compendium
September 2021
Volume 42, Issue 8
Peer-Reviewed

Anterior Maxillary Growth in Implantology: Complications, Management, and Prevention

Andre P. Saadoun, DDS, MS

Abstract

Osseointegrated implantology initially concerned fully edentulous patients, then in time involved partially edentulous patients, and finally, has developed to include patients with single teeth missing on healed ridges and immediate implant placement after extraction. Thus, it was within a normal range of evidence to place implants in adolescents with congenital agenesis or prone to accidents or young adults under 30 after failure of a conservative dental treatment. However, over time the dental profession came to realize that this treatment modality was vulnerable to complications induced by maxillary/mandibular anterior growth with these patients. Although the literature may support the efficacy of osseointegrated implants for fully and partially edentulous patients, care and monitoring must be exercised over at least a 15-year period when treating adolescents with incomplete bone formation with single-tooth replacement.

Currently, osseointegrated implantology is one of the most used methods for rehabilitation of patients with full, partial, or single-tooth edentulism and has been a major advance in dentistry providing a high level of predictability. The foundations of modern implantology were laid by Professor Bränemark et al in 1969, who noted that certain multi-potential undifferentiated cells were formed and released from bone marrow.1 This led to the early recognition that bone would come in contact with implantable titanium chambers.2 The base of Bränemark et al's research was developed through intimate knowledge of the inflammatory process and bone healing. Osseointegration provides an attachment mechanism for non-vital titanium components to living bone. This phenomenon was demonstrated repeatedly in both preclinical and clinical trials.3-5 These researchers captured the attention of the dental industry.

In 1985, implantology was limited to dentists with surgical training, such as oral surgeons and periodontists. At the time, there was a need for further implant education to provide dentists with basic surgical principles. When osseointegration was introduced to the dental practice, Dr. Bränemark's directions were used. The implant studied was the original Bränemark machined-surface implant with a screw-shaped fixture and external hexagon prosthetic connection. These implants were manufactured from commercially pure titanium. They were placed according to Bränemark's and the manufacturer's instruction. All periodontal disease was treated and eliminated before implants were installed. The applied method of treatment was considered successful from not only a short-term but also a long-term perspective.

Various authors published definitions of success criteria in implantology.3,6,7 Success included the absence of the following characteristics: implant mobility, radiolucency of peri-implant tissues, pronounced extent of resorption of bone tissue in the area of the implant platform, infection, and patient discomfort. Eventually, esthetics would become a part of implant success criteria.8

The expansion of implant therapy to a wider swath of practitioners with varying levels of education and experience led to clinical approaches of osseointegration. It is likely that less attention paid to patient selection, periodontal health and compliance of the patient, treatment planning, surgical technique, and implant designs has probably contributed to an increase in problems involving peri-implantitis and maxillary growth complications. The latter include disharmony of gingival margins and incisal edge levels of restorations in comparison to adjacent natural teeth over time. Meanwhile, many implant manufacturers worldwide have developed numerous innovations and changes in the shape, surface, and connection of implants.

In the early years, two-stage surgeries were performed, but later cases often had healing abutments placed in a single-surgery approach, following ridge healing and/or tooth extraction. Immediate implant treatment for extraction wounds was introduced in 1989 and opened new horizons to several other modalities.9,10

Clinicians were comfortable anticipating long-term predictability based on Bränemark's research. If long-term functional success of the implant treatment depends on the stability of the crestal bone tissue around the implant platform, then esthetic result is achieved by adequate soft tissue in the peri-implant zone.11 Thus, it is necessary to achieve not only osseointegration in the bone around the implant but also muco-integration of the soft tissue around the implant's sub- and suprastructure.12

Osseointegrated implants have demonstrated successful tooth replacement for many years, and single-tooth implants have become an increasingly popular method for replacing a missing single tooth. However, over the past 20 years, studies have shown that single tooth replacement with an implant placed in the anterior maxillary jaw in younger patients presents some periodontal and esthetic risks. This is related to the cessation and degree of vertical and horizontal growth of the single ankylosed implant restoration. There is a risk, therefore, of placing an implant prematurely in youths.13 The cessation and degree of vertical growth on a young patient are unpredictable and may result in infraposition of the implant, with teeth and gingival contours in disharmony with adjacent teeth, and may also lead to periodontal bone loss around the implant and neighboring teeth (Figure 1 through Figure 4).

Clinicians should be aware of this fact and inform their patients that these changes may eventually compromise the esthetic result of the treatment and involve complex modalities of treatment to solve the complication. This article presents a clinical implant case in which an implant was placed in a young patient in 1995, many years before this biologic growth phenomenon was known to clinicians.

Clinical Case

History of the Case

In July 1995, 13 months after completing 5 years of orthodontic treatment (Figure 5), an 18-year-old female student consulted the author's dental office after experiencing a swing accident that resulted in fracture trauma on tooth No. 8. She was complaining of exquisite pain when touching the tooth and drinking cold liquids.

The clinical examination revealed a cervical line fracture with little mobility on tooth No. 8 and a small fracture in the mesial angle of tooth No. 9 (Figure 6). It was decided to keep No. 8 by performing endodontic treatment on the tooth (Figure 7) and placing an immediate temporary crown and to place a composite restoration on No. 9.

Unfortunately, a fistula appeared 4 weeks after the endodontic treatment and temporary crown placement on the buccal mucosa of No. 8, and it was then decided to extract the tooth and place an implant immediately (Figure 8).

The surgical session was planned and performed (Figure 9 through Figure 13), and it was then possible to realize that the cervical fracture followed a bevel to the coronal third of the root. The apical part of the root was removed and the alveolar well-degranulated without touching to the fistula. A 5-mm diameter implant with external hex with smooth collar (Replace, Nobel Biocare, nobelbiocare.com) was placed in the center of the alveolar socket, respecting the rules of implant positioning defined in 1992.14

A 5-mm diameter customized healing abutment was screwed into the head of the implant and a bone graft (Bio-Oss®, Geistlich, geistlich-pharma.com) was packed in the remaining gap and on the buccal ridge; a coronally advanced flap enabled interrupted sutures without tension. The surgical trauma was uneventful and the buccal fistula disappeared after 3 weeks. An implant impression was taken at 6 months using an impression pin with the same cervical shape of the healing abutment (Figure 14 through Figure 17).

A temporary crown respecting the cervical contouring concept,15 with a flat, small shape on the buccal/palatal and a convex one on the proximal surfaces, was placed to obtain an optimal emergence profile. In September 1996, a ceramo-metal restoration with a titanium/zirconia abutment and laminate veneer were placed on No. 8, with a high pink and white esthetic score (Figure 18). Two years later in September 1998, during the buccal photography session, the esthetic natural smile of the now 19-year-old patient with a low lip line showed a slight discrepancy on the incisal edge (Figure 19); however, at the time this fact did not alarm the clinician nor the patient. However, it was, in fact, the beginning of an anterior maxillary growth complication.

Clinical Complications

In 2014, 16 years after the patient's last maintenance consultation and 18 years after the implant placement and tooth restoration, the patient returned to the clinic to show what was now a more pronounced uneven incisal edge and gingival contour between the two central incisors. With the knowledge the author had learned from the literature since 2000, the diagnosis of an anterior maxillary growth complication was readily established.

A careful clinical examination on the now 37-year-old patient with a low lip line showed an infraocclusion on No. 8 and a concave soft-tissue defect with a very thin non-attached keratinized gingiva above the implant restoration, with a probing depth of 5 mm. The CT scan examination showed loss of half the buccal cortical plate, but with an implant in the correct 3-dimensional position and without any mobility (Figure 20 through Figure 23). It was decided to address these complex issues with peri-implant/soft-tissue treatment (by the author [APS] in Paris, France) and changing the restoration in collaboration with the author's colleague Dr. Giancarlo Pongione (GP) and his laboratory technician, Della Neve (DN), in Napoli, Italy.

The digital smile design (DSD) analysis performed by GP revealed a disharmony in the soft-tissue contours of 3 mm with the implant No. 8 restoration being on a higher level, and a discrepancy of 2 mm in the incisal edge level with the natural tooth No. 9 being on the lower level (Figure 24 and Figure 25). The DSD analysis also suggested that in order to remove all disharmony on the soft-tissue and incisor levels, the implant restoration on No. 8 needed to be changed and an internal bevel gingivectomy needed to be performed on tooth 9. Definitively, this was ample information to establish a treatment plan for this highly complex clinical situation.

Clinical Management

The treatment was conducted in two phases: the periodontal treatment to increase the soft-tissue thickness (by APS), and the restorative treatment to change the existing implant abutment and restoration (by GP).

The periodontal phase began in March 2014. It was decided to use a tunnel approach to insert initially an acellular dermal matrix (Figure 26 through Figure 28), and then 10 weeks later, in May 2014, a connective tissue graft (CTG) (Figure 29 through Figure 31).

The restorative phase started in July 2014. The old restoration and abutment were removed and another abutment with an initial temporary crown were placed to initiate the correct shape of the healing soft tissue (Figure 32 through Figure 34).

In the meantime, the laboratory technician (DN) created a new hybrid abutment and new temporary crown for the implant No. 8 and a laminate veneer for the tooth No. 9 (Figure 35 and Figure 36).

Two months later a new hybrid abutment for the external hex, which was more difficult to manage because of the large external hex with a crown restoration, and laminated veneers were ready to be placed (Figure 37 through Figure 39).

In September 2014, the soft tissue had increased thickness and an improved profile. The implant abutment was screwed to the implant and then the restoration, and the laminated veneers were cemented. However, clinically a 1-mm soft-tissue marginal contour discrepancy was still showing on this patient with a low lip line (Figure 40 through Figure 43). Another x-ray was taken that same month and compared to the initial one from September 1996, and it confirmed that the level of interproximal bone on the adjacent teeth did not change after 18 years; the soft-tissue maturation was still ongoing (Figure 44 through Figure 46).

In December 2014, at a follow-up appointment, the patient reported being satisfied with the esthetic result of her smile, thanks in part to her low smile line; but the author, as the periodontist, was not totally satisfied with the soft-tissue margin level between Nos. 8 and 9 (Figure 47). Table 1 delineates the different points of view between the clinician and patient.

In May 2015, 14 months after the initial peri-implant soft-tissue management and 9 months after the implant and tooth restorations, there was no more gingival or incisal edge discrepancy (Figure 48). Furthermore, the final photograph (Figure 48) revealed gingival margin contours similar to those found at the end of the orthodontic treatment, which, based on clinical observations, were induced by gingival genetic memory.16

Altogether, the patient and the clinicians were fully satisfied with the functional and esthetic outcomes, with a PES (pink esthetic score) and WES (white esthetic score) of 10. As it has been said, time, oral hygiene, and genetic memory are the best allies for soft tissue.16

Discussion

Over the past 20 years research has indicated that adult growth does occur with aging. This should serve as a warning to clinicians. The interest in implant complications in the 21st century is significant as evidenced by the number of publications in scientific journals, the percentage of time devoted to continuing education programs, and the necessary change of paradigm in the treatment of missing anterior teeth replacement by implant, especially in young patients from 15 to 35 years old.

Conversion of cartilage, sutural deposition, and periosteal remodeling are the basic phenomena involved in growth mechanisms. The principles of bone growth cause changes in the size and shape of the mandible and the nasomaxillary complex in three dimensions. The growth rate varies at different times during child development. The processes of facial growth and changes in the dental arches continue until a much later age than had previously been realized.17

Oesterle and Cronin in 2000 were among the first authors to describe the effects of growth on implants placed in children and document the changes that occur in adults over decades rather than rapidly, as seen in children.18 Aging changes are readily apparent in the soft tissues of the face and create dramatic changes. Changes in the jaws and teeth occur as a result of continued, slow growth in contrast to the aging effects seen in soft tissues. Growth changes occur in the arches and result in adaptive changes in the teeth over time, both vertically and horizontally and with regard to alignment. These dental changes may result in a lack of occlusion vertically or malposition of adjacent natural teeth relative to the implant crown restoration. Clinicians should observe and report these changes and warn patients that changes can occur over the service life of the implant-supported crown. These changes may require maintenance adjustments or possible remaking of the implant crown as a result of adult growth, wear, or the esthetic changes that come with aging.

Rossi and Andreasen in 2003 reported implants do not follow the normal growth of the jaws and behave like ankylosed teeth.19 Implants may also interfere with the normal growth of the alveolar process and jeopardize the germs of adjacent permanent teeth or alter eruption with unfavorable clinical and radiographic findings in the anterior maxilla.

Op Heij et al's report in 2003 indicated that jaw growth may be highly compromising for oral implants.20 Nevertheless, implants are increasingly placed in adolescents. Especially after trauma of a maxillary incisor, one could question what the minimum age a patient should be before a solitary implant is placed. Because of the osseointegrated character of implants they behave like an ankylosed element and do not follow the further evolution of the jawbones and certainly not of the alveolar process. This could lead to unesthetic situations, especially in the anterior region with relative infraocclusion and disharmony in the gingival contours.

The anterior maxillary bone is the most at risk to observe complications such as infraocclusion and implant buccal bone resorption. Clinically, radiologically, and histologically, it appears that implants do not follow the formation and development of the alveolar process. At some distance from the implant, tissues developed normally, but not in the immediate vicinity of the implant. The latter observation can lead to unesthetic and nonfunctional situations and loss of occlusal contact, along with periodontal complications such as angular proximal defect around neighboring teeth.13

In 2008, De Rouck et al described the growth of jawbones and, hence, attempted to reach some directives to determine the ideal age for implant placement. Most attention was given to the large variation in the development of the alveolar process, especially between facial types (short versus long face). Additionally, the development of the alveolar process after age 20 was analyzed in detail. The article highlighted further changes that might jeopardize the outcome of implants and provided guidelines concerning the ideal timing for oral implant placement in the growing child, taking into account the further anticipated development of the jawbones and especially the continued eruptive movement of teeth, even after reaching occlusal contact. The latter, unfortunately, is not limited to puberty as generally believed, but can still apply even after age 18, with eruptive tooth movement reaching potentially significant dimensions especially in cases of a deviant facial type (long versus short face).

Andersson et al in 2013 reported in a 17-to 19-year follow-up study that 47 out of 57 patients (82%) showed up for the final examination after an average of 18 years.22 Two implants failed (18 years' cumulative survival rate [CSR] = 96.8%), and eight original single-crown implant restorations were replaced (CSR = 83.8%). Three of the crowns were replaced because of infraposition. About 40% of the patients showed signs of infraposition, which was similar in younger and older age groups but more frequently observed in female patients at the termination of the study. There was a weak trend indicating an association between "long-face" appearance and infraposition of the crown restoration, and patients were more satisfied with the esthetic clinical result than the participating clinicians. Patients seemed to pay less attention to the degree of infraposition in their esthetic assessments as compared with the clinicians.

A multidisciplinary and minimally invasive approach should be used to treat single anterior edentulism, keeping in mind the connection between the biology of maxillary bone growth and implant osseointegration. It is necessary to factor in the dynamic process of skeletal and dentoalveolar growth to establish the correct treatment, especially on young patients.23

In 2015, Schwartz-Arad and Bichacho presented a 16-year study on 35 patients (21 females and 14 males, mean age 29.3 ± 9.9 years) that evaluated the effect of age on mean submersion rate of single dental implants in the maxillary central incisor area as compared with the adjacent natural tooth in implants placed after growth had ceased.24 In their results the authors found that in the younger age group (<23 years), the submersion rate was more than three times higher than in the older age group (>30 years), yielding submersion rates of 1.02% and 0.27% per year, respectively. They concluded that whereas implant submersion continues throughout adult life, its rate varies with age. It is evident that this phenomenon is much more conspicuous during the second and third decades of life as compared with the fourth and fifth.

It is, therefore, contraindicated to place dental implants before growth and development are completed as the implants will be at risk of submersion due to continuous growth, creating potential functional, periodontal, and esthetic problems. Ongoing subtle growth changes have now been proven in adult men and women and become visible in the form of open contacts and mesially drifting teeth, open contact to implant restorations, and periodontal defects on adjacent teeth (Figure 49 through Figure 56).24

Some of the effects due to growth can be controlled by subtle treatment modifications, but others may require complete replacement of the implant and abutment. Occlusion changes, in particular, will affect function and may require dental intervention. Ideally, the patient will have been informed about such age-related changes. When changes in tooth position relative to implant restorations secondary to long-term adult growth occur, they can cause problems that are difficult or even impossible to correct.25,26

Bousquet and coauthors in 2016 reiterated that osseointegrated implants behave like ankylosed teeth, and their evolution does not follow the alveolar processes of adjacent teeth during growth.27 This growth decreases after 20 years but remains present. This can lead to infraposition functionally and esthetic failure for the implant therapy. Risk factors like the patient's age, sex, and shape of the face must be evaluated. Those authors recommended, for the first time in the literature, that the implant be placed in a more palatal position, a CTG be added at the buccal implant site, and a screw-retained implant restoration be used that could be readily changed if infrapositioning occurs during future years of aging.

In 2019, Cochetto et al published an interesting mid- and long-term study on this topic.28 From January to June 2017, all young adult patients who in the past 5 to 20 years had received implant restorations in the anterior maxilla in the same clinic were recalled for assessment of the presence of crown infraocclusion. Sixty patients were recalled-26 males and 34 females-with 76 implants included in the study. Patients were divided into two groups according to age (Group 1: <30 years, 12 males, 14 females; Group II: >30 years, 14 males, 20 females). Digital photographs, taken at the time of final prosthesis delivery (T0) and at the time of the study examination (T1), were compared by three blinded previously calibrated examiners. Cast models of the dental arches were taken at T1 and served as a reference for infraocclusion measurements. Cases were put in three categories: infraocclusion <0.5 mm, infraocclusion 0.5 mm to 1 mm, and infraocclusion >1 mm. An Awareness Perception Score (APS) was prepared to classify patients in one of the four following categories: "unaware patients" (0), "aware but disinterested patients" (1), "aware patients requiring explications" (2), and "aware patients requiring treatment" (3).

Their results showed the following: Infraocclusion was present in 73.3% of all cases, 65.4% among males, 79.4% among females. Infraocclusion was <1 mm in 88.2% of males and in 85.1% of females. No significant differences were found for sex or for age. The overall APS was: "unaware patients" = 38.6%, "aware but disinterested patients" = 27.3%, "aware patients requiring explications" = 15.9%, and "aware patients requiring treatment"= 18.2%.

Recently, Polymeri et al in 2020 evaluated the effect of continuous tooth eruption on the outcomes of single implant-supported restorations in the anterior maxilla of adults (76 patients, aged 21 to 78 years).29 Their results showed thatinfraocclusion increased over time by 0.08 mm ± 0.02 mm per year. Infraocclusion was more pronounced for delayed (0.09 mm/year) than immediate (0.06 mm/year) implant placement and for younger versus older adults (0.0013 mm/year per additional year of age); no statistically significant association between infraocclusion and sex, ethnicity, implant site, timing of implant temporization, surgical protocol, or type of restoration was found. The authors concluded that infraocclusion of single implant-supported maxillary anterior restorations may result in esthetic concerns over time.

Management of Anterior Maxillary Growth Complications

In the presence of an implant complication resulting from anterior maxillary growth, such as disharmony on the incisal edge and/or on the gingival marginal contour between the natural adjacent tooth and implant restoration, several modalities of treatment could be chosen, ranging from minimally invasive to more traumatic. Treatment may be dependent on the implant hard/soft-tissue defect, the patient's awareness of malfunction, esthetics, and the patient's agreement with the preconized treatment.

Different treatment modalities for these complications may include:

• retain the implant and abutment and place a new implant restoration 
• retain the implant restoration with limited soft-tissue contour/tooth restoration modification
• retain the implant, maintain the abutment, and change the restoration with ceramo-composite for esthetic soft-tissue management  
• retain the implant and change the abutment/restoration with ceramo-composite for esthetic soft-tissue management  
• retain the implant/abutment with crown lengthening of the natural adjacent teeth, increase soft-tissue thickness with a CTG, and place a new implant restoration 
• retain the implant, increase soft-tissue thickness with a CTG, and place a new implant/abutment/restoration
• retain the implant, modify the abutment, place a CTG, and place a new implant restoration
• perform implant extraction, followed by bone grafting and ridge regeneration, CTG, new implant with new abutment and restoration 

Biological Factors: Decisions of Prevention

The literature seems to lack descriptions/illustrations of clinical management or prevention of anterior maxillary growth complications in implantology through clinical cases of typical implant placement after extraction. The case report described in this article and a review of the literature from the past 25 years should make clinicians cognizant of the complications associated with placing implants in the anterior maxillary area with ongoing skeletal growth. Biological factors include craniofacial changes that occur with age and common implant problems that may happen over time due to aging.26 The Cochetto et al (2019) concluding remarks (summarized below) should also be considered.28 Advantages and disadvantages between teeth and implant restorations on short- and long-term bases are also factors.30 Knowing these issues should aid clinicians in deciding the optimal choice for a patient's treatment plan.

Common craniofacial changes due to age include: (1) Anterior face height increases with the most increase happening in the lower dentoalveolar area. (2) Females have shown the most eruption in the maxillary anterior region and mandibular first molar region; they have also demonstrated a palatal tip in the anterior region. (3) Facial height increases by as much as 1.5 mm, which can lead to an increase in vertical overlap; for women, this usually is combined with a palatal tip in the anterior region. (4) Mandibular angles increase more in females compared to males. Males have shown an anterior rotation of the jaw, while females show a posterior rotation of the mandible. (5) Maxillary molars of both genders have demonstrated a mesial drift.28

Common implant changes that happen due to aging include:(1) Occlusion changes are most common. Increased growth usually causes natural teeth to migrate. As a result, open contacts occur between natural teeth and implants. Loss of contact was more common in the mandible and increased with age. (2)Incisal edge changes, gingival margin height, and loss of facial contour alignment are commonly seen changes in anterior implants. (3) The labial plate thins out in anterior implants due to subtle growth changes, and these changes are more common in women compared to men.29

The Cochetto et al study concluding remarks are as follows28: (1) Craniofacial growth in a young adult is a proven fact, and it becomes a problem when implants are placed in the anterior region. (2) Infraocclusion, irregular gingival margin, and interproximal contact loss are the most frequent complications. (3) The most significant cases are mainly in the anterior zone. (4) This problem evolves over a long period of time and varies greatly in its progression and expansion depending on the face profile. (5) Clinical signs have been more associated with females and skeletal long faces. (6) The clinical onset/relevance is generally minimal, but, in some cases, serious esthetic/functional complications may manifest; this point should be given attention during treatment planning in the esthetic zone. (7) Other modalities and alternatives to implant treatment should always be considered. (8) The patient should be informed about these complications, and medico-legal responsibilities should be clarified.

Teeth versus implants: Both teeth and implants can maintain long-term stability with good oral hygiene maintenance. Complications affecting long-term instability of teeth include: mechanical complications, such as agenesis, decay, crown/root fracture, and trauma; inflammatory complications, such as gingivitis, periodontitis, and endodontic infection; esthetic complications, such as teeth malposition, disproportion, and discoloration, gingival (gummy) smile, and gingival recession.

Complications affecting long-term instability of implants include: mechanical complications, such as fracture of the components (crown, abutment, implant); inflammatory complications, such as perimucositis and peri-implantitis; systemic complications, such as titanium hypersensitivity, allergy, and implant surface corrosion; esthetic complications, such as precise implant 3D positioning, emergence profile, peri-implant soft-tissue recession, contour hyperplasia, discoloration of the peri-implant soft tissue by transparency, disproportion between adjacent teeth and the implant restoration, and vertical and horizontal maxillary growth.

Socket Shield Technique and Maxillary Growth

Can a root shield procedure or partial extraction therapy with immediate implant placement be used to prevent anterior maxillary growth complications? The socket shield technique maintains the buccal portion of the tooth in the extraction socket to preserve buccal bone. In the esthetic zone, use of the socket shield technique has shown promising results in maintaining soft and hard tissues around implants and providing a possible solution for a reliable esthetic outcome.31

Some may presume that because of the periodontal ligament fibers of the partial buccal root remaining attached to the internal alveolar bone, the bone (bundle plus cortical plate) close to the implant will follow the maxillary growth and no disharmony will be detected or observed over time in gingival level contour or incisal edge, or that no other complications typically found in conventional immediate implant placement should be expected. If this thinking is correct, practitioners should not find any esthetic or functional problem, clinically or radiographically, years later when checking the socket shield procedure cases on patients implanted between 15 and 35 years old. However, a long-term failure in the socket shield technology is possible. As with any new technique, specific complications, like infection of the buccal piece of tooth, can occur. Zuhr et al in 2020 presented a clinical case in which a complication developed with the socket shield technique because of an anterior maxillary growth.32 The mobile root shield could be seen in contact with the crown on the implant with a small amount of the implant surface being exposed. It is known that the maxilla grows in an anterior-caudal direction for lifetime growth, as in the case presented by Zuhr et al.32 The natural tooth was in a more coronal position than the adjacent implant restoration. The root shield was not locked with either the implant threads or with an ingrowth of bone, ankylosing the shield. Hence, the shield acted like a natural tooth in terms of vertical displacement by following the growth of the maxilla. Since the implant was ankylosed, the shield came into contact with the implant-retained crown after some years of function. This allowed bacteria to migrate into the space between the implant and the shield resulting in inflammation. The consequential surgical management was described as fully successful after removal of the loose root portion and bone grafting in the implant bone defect vicinity, which was covered with a tuberosity CTG. Thus, possible failures can occur with the socket shield procedure. Identifying possible risk factors and complications with this technique is essential for its successful application in implant therapy.

These conclusions agree with the following comments from Drs. Maurice and Henry Salama speaking on maxillary growth in submerged and partial extraction therapy in a personal correspondence with the author in 2020: In adult maxillary growth, the natural teeth erupt and, of course, because of osseointegration the implant does not. Usually, the result is an implant restoration incisal edge that is apical (infraocclusion) to the adjacent natural teeth and a peri-implant gingival contour margin that is apical to that of the adjacent teeth. However, since there is a free labial tooth segment in cases of socket shield protection/partial extraction therapy, that segment is biologically capable of erupting in a similar fashion as the adjacent teeth, and, therefore, all of the gingival margins may remain in harmony until some complication arises such as the apparition of the root portion through the margin.

Observations and Conclusions

Earlier perceptions toward anatomical growth were simply that adults grew until they reached their twenties. Based on this premise, dentists used static oral and cranial landmarks to place dental implants for edentulous patients. Because growth was considered to be finished, there was no concern about displacement or wandering of the implants.

Now, it is established that craniofacial growth continues throughout life, and growth rate varies at different times during the age development. This growth is multidirectional, occurring in sagittal, vertical, and transverse planes. It does not happen at a fixed pace; slow periods of growth are followed by phases of accelerated growth called growth spurts. The process of facial growth and changes in dental arches continues to a much later age than had previously been realized. Mid-term study should be longer than 6 years to observe the signs of vertical infraposition with infraocclusion on the implant crown restoration.33

In fact, the speed of growth decreases but constant modifications occur in the bone structure of both men and women. Furthermore, the actual craniofacial and jaw changes that take place differ from men to women. This growth will affect implant placement as implants fuse or ankylose into bone when placed. Implants are incapable of moving or adjusting to growth changes. Over time, these growth changes may result in distinct esthetic and functional problems with the implant restorations. This becomes particularly apparent with a single implant placed alongside adjacent teeth in the anterior jaws, with potential esthetic, occlusal, and periodontal ramifications possible.

Dentistry has evolved to become a less invasive practice, with greater emphasis on meeting esthetic and functional objectives and incorporation of interdisciplinary approaches in order to respect overall patient parameters. Successful implant treatment outcomes in children have been achieved with interdisciplinary cooperation.34,35

The orthodontist, periodontist, and restorative dentist, for example, should be in constant communication to ensure the optimal rehabilitation of an anterior missing tooth, and have precise knowledge of the patient's age, bone biology, dynamic skeletal and dentoalveolar growth, and soft-tissue management to maintain ideal function and esthetics throughout implant osseointegration. This approach is essential to indicate and determine the best choice of restoration, whether tooth or implant.36

Thus, in light of the knowledge dentistry has today, it is important to prevent and avoid the appearance of infraocclusion and peri-implant soft-tissue recession of the implant restoration long term. A growing controversy with regards to placing implants in the esthetic zone has developed among clinicians. Some are still recommending placing an implant in the anterior maxillary region in patients under age 35, while others are suggesting that no implant be placed in these patients in order to prevent the aforementioned complications.37

The American Academy of Osseointegration in its September 2020 journal stated, "It is time to flatten the implant curve, and teeth should be preserved as long as possible."38 Thus, a new paradigm is emerging in dental treatment regarding teeth restoration versus implants, as per the following practical recommendations39-42:

• Use a dental digital smile implant restoration to evaluate the future clinical situation a few years after placement.
• Avoid placing a dental implant on single edentation on a patient less than 25 to 30 years old with a high lip line.
• Place a zirconia ceramic cantilever resin-bonded fixed dental prosthesis combined with a subgingival CTG on the edentulous ridge to improve the esthetic shape of the pontic (Figure 49 through Figure 56.)
• Choose a symmetrical situation to place an implant on patients 25 to 30 years old and delay any implant placement in all other situations.
• Place the implant in a palatal position combined with a bone graft in the buccal gap.
• Increase the buccal soft-tissue thickness with a CTG.
• Maintain and protect the implant biological width with a transmucosal abutment.
• Modify the concave emergence profile of the screw-retained temporary crown.
• Use a screw-retained implant restoration with bone graft/CTG that will facilitate the change of only the restoration in case anterior maxillary growth complications present later.
• Always treat a cantilever bonded bridge with CTG below the edentulous site with patients between 25 and 30 years old.

Then, if in the future an anterior maxillary growth complication occurs and the final implant restoration presents a disharmony in the incisal curve but no disharmony in the gingival contours because of the soft-tissue thickness that was achieved, the implant restoration can be simply and easily unscrewed and changed.

Acknowledgment

Dr. Saadoun would like to dedicate this article to Dr. D. Walter Cohen, the founding editor of Compendium, who was his dean and mentor.

About the Author

Andre P. Saadoun, DDS, MS
Diplomate, American Academy of Periodontology; Diplomate, International Congress of Oral Implantologists; Private Practice limited to Esthetic Periodontics and Implant Surgery, Paris, France

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